L-carnitine
updated
Levocarnitine treats defined carnitine-deficiency states. A 37-trial meta-analysis estimated 1.21 kg lower body weight than control, while a direct 24-week obesity trial was null. The approved U.S. injection is intravenous only.
Endogenous quaternary ammonium fatty-acid carrier
- The U.S. prescription injection is labeled for IV use only.
- A 37-trial synthesis estimated 1.21 kg lower mean weight, but waist and body-fat percentage were not significantly changed.
- A direct eight-week oral trial in 36 overweight women was null among completers.
- A Chinese IV pilot combined drug with seven days of calorie restriction and fasting, so it cannot isolate a durable stand-alone effect.
- The 17.4-hour terminal value belongs to a specified IV bolus.
- Serious hypersensitivity and a warfarin INR interaction appear in the current label.
What does “L-carnitine” mean in the claim you are evaluating?
First identify both purpose and route. Prescription levocarnitine can treat defined carnitine-deficiency states. Oral supplements have been studied for weight outcomes. The current US injection label is IV only. An IM or SC “fat-loss shot” is therefore a different route, product-quality question, and evidence claim.
| Claim | What the evidence actually covers |
|---|---|
| Deficiency treatment | US-labeled IV medicine for defined secondary carnitine-deficiency states |
| Oral weight supplement | Heterogeneous trials with a modest pooled mean and at least one direct null study |
| IV weight experiment | A tiny seven-day fasting pilot, not routine supplement evidence |
| IM or SC fat-loss shot | No qualifying controlled single-ingredient human trial in the cited evidence |
US label · IV deficiency treatment
FDA prescribing information
DailyMed. Levocarnitine injection, solution. Updated July 2, 2026.
The current label says FOR INTRAVENOUS USE ONLY and limits treatment to acute or chronic secondary carnitine deficiency from inborn errors and prevention or treatment of deficiency in patients with end-stage renal disease on dialysis. It reports a 17.4-hour mean apparent terminal elimination half-life after a specified 20 mg/kg IV bolus, serious hypersensitivity including anaphylaxis, and postmarketing INR increases with warfarin. It also says clinical outcomes from correcting plasma carnitine in dialysis have not been determined.
- Participants / model
- Patients with qualifying secondary carnitine deficiency or end-stage renal disease undergoing dialysis
- Treatment
- Prescription levocarnitine injection by intravenous administration
- Follow-up
- Label evidence spans single-dose pharmacokinetics and clinical use; it does not define a weight-loss course
- Study design
- Regulatory prescribing information
- Funding
- Manufacturer regulatory submission
This label does not authorize IM or SC administration, weight loss, or transfer of IV pharmacokinetics to oral products.
Read the original sourceFDA approval · dialysis deficiency
FDA approval action
US Food and Drug Administration. NDA 20-182/S-006 approval letter. December 15, 1999.
FDA approved the supplemental indication for prevention and treatment of carnitine deficiency in patients with end-stage renal disease undergoing dialysis. The action concerns Carnitor injection and does not establish an obesity indication or an IM or SC route.
- Participants / model
- Patients with end-stage renal disease undergoing dialysis
- Treatment
- Carnitor levocarnitine injection
- Follow-up
- Regulatory action
- Study design
- FDA supplemental approval letter
Approval scope is indication and product specific.
Read the original sourceIM and SC routes · no controlled fat-loss result
PubMed and trial registry records
PubMed, ClinicalTrials.gov, ChiCTR, and Russian-language records for intramuscular or subcutaneous L-carnitine.
The cited records include no controlled single-ingredient human trial of intramuscular or subcutaneous L-carnitine for fat loss. They instead describe intravenous levocarnitine, intramuscular acetyl-L-carnitine for pain, or multi-ingredient topical products.
- Participants / model
- Human fat-loss studies using intramuscular or subcutaneous levocarnitine
- Treatment
- Intramuscular or subcutaneous single-ingredient L-carnitine
PubChem · chemical identity
Government chemical database
National Library of Medicine. PubChem Compound Summary for CID 10917, levocarnitine.
Identifies levocarnitine as the biologically active R stereoisomer of carnitine, with molecular formula C7H15NO3, molecular weight 161.20 g/mol, and CAS Registry Number 541-15-1.
- Participants / model
- Not applicable
- Treatment
- Not applicable
- Follow-up
- Database record
- Study design
- Curated chemical identity record
Identity data do not establish a clinical outcome.
Read the original sourceWhat is levocarnitine injection actually approved to treat?
The U.S. label covers acute or chronic secondary carnitine deficiency caused by inborn errors of metabolism and prevention or treatment of deficiency in people with end-stage renal disease on dialysis. It does not list obesity, weight loss, or athletic performance.
Even inside the dialysis indication, correcting a laboratory deficiency and proving a patient-centered benefit are different questions. The label says the clinical significance of raising plasma carnitine in dialysis has not been determined.
US label · IV deficiency treatment
FDA prescribing information
DailyMed. Levocarnitine injection, solution. Updated July 2, 2026.
The current label says FOR INTRAVENOUS USE ONLY and limits treatment to acute or chronic secondary carnitine deficiency from inborn errors and prevention or treatment of deficiency in patients with end-stage renal disease on dialysis. It reports a 17.4-hour mean apparent terminal elimination half-life after a specified 20 mg/kg IV bolus, serious hypersensitivity including anaphylaxis, and postmarketing INR increases with warfarin. It also says clinical outcomes from correcting plasma carnitine in dialysis have not been determined.
- Participants / model
- Patients with qualifying secondary carnitine deficiency or end-stage renal disease undergoing dialysis
- Treatment
- Prescription levocarnitine injection by intravenous administration
- Follow-up
- Label evidence spans single-dose pharmacokinetics and clinical use; it does not define a weight-loss course
- Study design
- Regulatory prescribing information
- Funding
- Manufacturer regulatory submission
This label does not authorize IM or SC administration, weight loss, or transfer of IV pharmacokinetics to oral products.
Read the original sourceFDA approval · dialysis deficiency
FDA approval action
US Food and Drug Administration. NDA 20-182/S-006 approval letter. December 15, 1999.
FDA approved the supplemental indication for prevention and treatment of carnitine deficiency in patients with end-stage renal disease undergoing dialysis. The action concerns Carnitor injection and does not establish an obesity indication or an IM or SC route.
- Participants / model
- Patients with end-stage renal disease undergoing dialysis
- Treatment
- Carnitor levocarnitine injection
- Follow-up
- Regulatory action
- Study design
- FDA supplemental approval letter
Approval scope is indication and product specific.
Read the original sourceDid the dialysis trials prove better exercise capacity or quality of life?
Each of two 24-week randomized trials missed its prespecified VO2max comparison with placebo. A combined secondary analysis suggested less deterioration and a better fatigue score, while total quality of life and other domains did not improve.
Study A randomized 28 people to 20 mg/kg IV after dialysis and 28 to placebo. Study B randomized 32, 30, and 32 people to 10, 20, and 40 mg/kg and 33 to placebo. The pooled secondary signal should stay labeled secondary.
Dialysis trials · primary VO2max analyses negative
Two randomized placebo-controlled trials
Brass EP et al. American Journal of Kidney Diseases. 2001. PMID 11325685.
Two 24-week trials tested IV L-carnitine after dialysis. Study A randomized 28 to 20 mg/kg and 28 to placebo. Study B randomized 32, 30, and 32 to 10, 20, and 40 mg/kg and 33 to placebo. Each study failed its prespecified VO2max comparison. A combined secondary analysis suggested less decline in exercise capacity and improvement in the fatigue domain, while total quality-of-life score and other domains did not improve.
- Participants / model
- Adults receiving maintenance hemodialysis
- Treatment
- IV L-carnitine after dialysis at 10, 20, or 40 mg/kg versus placebo
- Follow-up
- 24 weeks
- Study design
- Two multicenter randomized double-blind placebo-controlled trials
- Funding
- Sigma-Tau Pharmaceuticals
Secondary pooled signals do not convert negative prespecified primary analyses into a proven functional benefit.
Read the original sourceUS label · IV deficiency treatment
FDA prescribing information
DailyMed. Levocarnitine injection, solution. Updated July 2, 2026.
The current label says FOR INTRAVENOUS USE ONLY and limits treatment to acute or chronic secondary carnitine deficiency from inborn errors and prevention or treatment of deficiency in patients with end-stage renal disease on dialysis. It reports a 17.4-hour mean apparent terminal elimination half-life after a specified 20 mg/kg IV bolus, serious hypersensitivity including anaphylaxis, and postmarketing INR increases with warfarin. It also says clinical outcomes from correcting plasma carnitine in dialysis have not been determined.
- Participants / model
- Patients with qualifying secondary carnitine deficiency or end-stage renal disease undergoing dialysis
- Treatment
- Prescription levocarnitine injection by intravenous administration
- Follow-up
- Label evidence spans single-dose pharmacokinetics and clinical use; it does not define a weight-loss course
- Study design
- Regulatory prescribing information
- Funding
- Manufacturer regulatory submission
This label does not authorize IM or SC administration, weight loss, or transfer of IV pharmacokinetics to oral products.
Read the original sourceHow large is the pooled weight-loss result?
A 2020 synthesis of 37 randomized trials and 2,292 participants estimated 1.21 kg lower body weight with L-carnitine than control, with a 95% confidence interval from 0.68 to 1.73 kg lower. Individual responses varied across the heterogeneous trials.
BMI and fat mass also moved modestly in the full analysis. Waist circumference and body-fat percentage did not significantly change, and when the authors restricted analysis to higher-quality studies, body weight was the only anthropometric outcome that remained significant.
37 trials · modest mean weight change
Systematic review and meta-analysis of randomized trials
Talenezhad N et al. Clinical Nutrition ESPEN. 2020. PMID 32359762.
Across 37 randomized trials with 2,292 participants, L-carnitine reduced body weight by a pooled 1.21 kg versus control (95% CI 0.68 to 1.73 kg lower). BMI and fat mass also moved modestly, while pooled waist circumference and body-fat percentage did not significantly change. Restricting the analysis to higher-quality studies left weight as the only significant anthropometric outcome.
- Participants / model
- Adults across heterogeneous randomized supplementation trials, not one defined obesity population
- Treatment
- L-carnitine supplementation in trial-specific oral or parenteral regimens
- Follow-up
- Varied across included trials
- Study design
- Systematic review and random-effects meta-analysis of 37 randomized controlled trials
- Funding
- Shahid Sadoughi University of Medical Sciences
A pooled mean from heterogeneous trials does not establish a large individual response, a specific injection route, or a gray-market product.
Read the original sourceWhat happened in the direct oral trial in overweight women?
Body mass, total fat mass, and resting lipid use did not differ between groups. The trial assigned 36 moderately overweight premenopausal women to oral L-carnitine or placebo with the same eight-week walking program.
Five women assigned L-carnitine withdrew because of nausea or diarrhea. The small null trial sits alongside the modest pooled estimate and shows the variation between studies.
36 women · oral trial was null
Randomized placebo-controlled trial
Villani RG et al. International Journal of Sport Nutrition and Exercise Metabolism. 2000. PMID 10861338.
Thirty-six moderately overweight premenopausal women were assigned to oral L-carnitine or placebo while walking four days per week for eight weeks. Among completers, body mass, total fat mass, and resting lipid use did not differ between groups. Five women assigned L-carnitine withdrew because of nausea or diarrhea.
- Participants / model
- 36 moderately overweight premenopausal women
- Treatment
- Oral L-carnitine or placebo with a standardized walking program
- Follow-up
- 8 weeks
- Study design
- Randomized double-blind placebo-controlled trial
Small size, attrition, one population, and an oral exposure limit what this null trial can settle.
Read the original sourceWhy did a Chinese IV pilot show more short-term weight loss?
The 30-person Guangzhou pilot tested IV L-carnitine during an intense seven-day program: two days of calorie restriction followed by five days of modified fasting. Mean weight fell 4.6 kg with L-carnitine versus 3.2 kg with saline, and waist reduction was larger.
That is a real randomized result under its tested conditions. It is also a tiny, acute, medically supervised cointervention study. It does not show that L-carnitine alone caused durable fat loss, and it says nothing direct about oral supplements or IM or SC injections.
China pilot · IV plus seven-day fasting
Randomized single-blind placebo-controlled pilot trial
Zhang JJ et al. Scientific Reports. 2014. PMID 25424121; ChiCTR-TNRC-12002835.
At a Guangzhou center, 30 adults with metabolic syndrome were randomized 15 per group during two days of calorie restriction followed by five days of modified fasting. The group receiving 4 g/day IV L-carnitine lost 4.6 kg on average versus 3.2 kg with saline (P=.03) and had a larger waist reduction. Hunger and fatigue ratings also favored L-carnitine.
- Participants / model
- 30 adults with metabolic syndrome at the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
- Treatment
- IV L-carnitine 4 g/day or saline during a seven-day medically supervised calorie-restriction and fasting program
- Follow-up
- 7 days
- Study design
- Randomized, single-blind, placebo-controlled pilot trial
- Funding
- Guangdong provincial and Chinese national research grants reported by authors
The tiny, acute, medically supervised fasting study cannot isolate a durable weight effect, does not test oral use, and does not test intramuscular or subcutaneous injection.
Read the original sourceWhy does moving fatty acids into mitochondria not guarantee body-fat loss?
Because transport capacity, moment-to-moment fuel use, and loss of stored body fat are different endpoints. Levocarnitine has a real carrier role. Whether adding more changes weight depends on baseline status, exposure, energy balance, and the clinical population.
| Endpoint | What it can establish |
|---|---|
| Mitochondrial transport | Biochemical role of endogenous carnitine |
| Acute substrate oxidation | Which fuels were used under a short laboratory condition |
| Body weight | Net mass change over a trial |
| Fat mass or waist | Body-composition or central-size outcome, which may diverge from weight |
US label · IV deficiency treatment
FDA prescribing information
DailyMed. Levocarnitine injection, solution. Updated July 2, 2026.
The current label says FOR INTRAVENOUS USE ONLY and limits treatment to acute or chronic secondary carnitine deficiency from inborn errors and prevention or treatment of deficiency in patients with end-stage renal disease on dialysis. It reports a 17.4-hour mean apparent terminal elimination half-life after a specified 20 mg/kg IV bolus, serious hypersensitivity including anaphylaxis, and postmarketing INR increases with warfarin. It also says clinical outcomes from correcting plasma carnitine in dialysis have not been determined.
- Participants / model
- Patients with qualifying secondary carnitine deficiency or end-stage renal disease undergoing dialysis
- Treatment
- Prescription levocarnitine injection by intravenous administration
- Follow-up
- Label evidence spans single-dose pharmacokinetics and clinical use; it does not define a weight-loss course
- Study design
- Regulatory prescribing information
- Funding
- Manufacturer regulatory submission
This label does not authorize IM or SC administration, weight loss, or transfer of IV pharmacokinetics to oral products.
Read the original sourceAcute IV study · fuel use, not fat loss
Human metabolic experiment
Natali A et al. Metabolism. 1993. PMID 8492714.
Acute IV carnitine experiments in healthy volunteers measured plasma carnitine and substrate oxidation during lipid infusion and exercise. They addressed short-term fuel selection under experimental conditions, not changes in body fat or body weight.
- Participants / model
- Healthy adult volunteers
- Treatment
- Acute IV L-carnitine under controlled metabolic conditions
- Follow-up
- Acute laboratory experiments
- Study design
- Human metabolic physiology experiments
A substrate-oxidation endpoint is not a clinical fat-loss endpoint.
Read the original source37 trials · modest mean weight change
Systematic review and meta-analysis of randomized trials
Talenezhad N et al. Clinical Nutrition ESPEN. 2020. PMID 32359762.
Across 37 randomized trials with 2,292 participants, L-carnitine reduced body weight by a pooled 1.21 kg versus control (95% CI 0.68 to 1.73 kg lower). BMI and fat mass also moved modestly, while pooled waist circumference and body-fat percentage did not significantly change. Restricting the analysis to higher-quality studies left weight as the only significant anthropometric outcome.
- Participants / model
- Adults across heterogeneous randomized supplementation trials, not one defined obesity population
- Treatment
- L-carnitine supplementation in trial-specific oral or parenteral regimens
- Follow-up
- Varied across included trials
- Study design
- Systematic review and random-effects meta-analysis of 37 randomized controlled trials
- Funding
- Shahid Sadoughi University of Medical Sciences
A pooled mean from heterogeneous trials does not establish a large individual response, a specific injection route, or a gray-market product.
Read the original source36 women · oral trial was null
Randomized placebo-controlled trial
Villani RG et al. International Journal of Sport Nutrition and Exercise Metabolism. 2000. PMID 10861338.
Thirty-six moderately overweight premenopausal women were assigned to oral L-carnitine or placebo while walking four days per week for eight weeks. Among completers, body mass, total fat mass, and resting lipid use did not differ between groups. Five women assigned L-carnitine withdrew because of nausea or diarrhea.
- Participants / model
- 36 moderately overweight premenopausal women
- Treatment
- Oral L-carnitine or placebo with a standardized walking program
- Follow-up
- 8 weeks
- Study design
- Randomized double-blind placebo-controlled trial
Small size, attrition, one population, and an oral exposure limit what this null trial can settle.
Read the original sourceIs there direct evidence for IM or SC L-carnitine fat-loss injections?
The cited evidence includes no controlled single-ingredient human fat-loss trial using either intramuscular or subcutaneous levocarnitine. The approved injection is IV, so neither its approval nor its 17.4-hour IV terminal value validates an intramuscular or subcutaneous product.
The cited records describe intravenous levocarnitine, intramuscular acetyl-L-carnitine for pain, or multi-ingredient topical products. None tested intramuscular or subcutaneous levocarnitine for fat loss.
IM and SC routes · no controlled fat-loss result
PubMed and trial registry records
PubMed, ClinicalTrials.gov, ChiCTR, and Russian-language records for intramuscular or subcutaneous L-carnitine.
The cited records include no controlled single-ingredient human trial of intramuscular or subcutaneous L-carnitine for fat loss. They instead describe intravenous levocarnitine, intramuscular acetyl-L-carnitine for pain, or multi-ingredient topical products.
- Participants / model
- Human fat-loss studies using intramuscular or subcutaneous levocarnitine
- Treatment
- Intramuscular or subcutaneous single-ingredient L-carnitine
US label · IV deficiency treatment
FDA prescribing information
DailyMed. Levocarnitine injection, solution. Updated July 2, 2026.
The current label says FOR INTRAVENOUS USE ONLY and limits treatment to acute or chronic secondary carnitine deficiency from inborn errors and prevention or treatment of deficiency in patients with end-stage renal disease on dialysis. It reports a 17.4-hour mean apparent terminal elimination half-life after a specified 20 mg/kg IV bolus, serious hypersensitivity including anaphylaxis, and postmarketing INR increases with warfarin. It also says clinical outcomes from correcting plasma carnitine in dialysis have not been determined.
- Participants / model
- Patients with qualifying secondary carnitine deficiency or end-stage renal disease undergoing dialysis
- Treatment
- Prescription levocarnitine injection by intravenous administration
- Follow-up
- Label evidence spans single-dose pharmacokinetics and clinical use; it does not define a weight-loss course
- Study design
- Regulatory prescribing information
- Funding
- Manufacturer regulatory submission
This label does not authorize IM or SC administration, weight loss, or transfer of IV pharmacokinetics to oral products.
Read the original sourceWhich adverse effects and interactions matter most?
The IV label reports serious immediate hypersensitivity, including anaphylaxis, laryngeal edema, and bronchospasm. It also reports increased INR with warfarin and calls for INR monitoring after levocarnitine starts or its exposure changes.
- Transient nausea and vomiting can occur; oral tolerability problems include diarrhea and gastritis.
- A characteristic body odor can occur from trimethylamine formation.
- With severe renal impairment, chronic high-dose oral use can accumulate trimethylamine and trimethylamine-N-oxide because dialysis does not efficiently remove them.
- Gray-market injection adds sterility, concentration, identity, and route-tolerance uncertainty outside the approved label.
US label · IV deficiency treatment
FDA prescribing information
DailyMed. Levocarnitine injection, solution. Updated July 2, 2026.
The current label says FOR INTRAVENOUS USE ONLY and limits treatment to acute or chronic secondary carnitine deficiency from inborn errors and prevention or treatment of deficiency in patients with end-stage renal disease on dialysis. It reports a 17.4-hour mean apparent terminal elimination half-life after a specified 20 mg/kg IV bolus, serious hypersensitivity including anaphylaxis, and postmarketing INR increases with warfarin. It also says clinical outcomes from correcting plasma carnitine in dialysis have not been determined.
- Participants / model
- Patients with qualifying secondary carnitine deficiency or end-stage renal disease undergoing dialysis
- Treatment
- Prescription levocarnitine injection by intravenous administration
- Follow-up
- Label evidence spans single-dose pharmacokinetics and clinical use; it does not define a weight-loss course
- Study design
- Regulatory prescribing information
- Funding
- Manufacturer regulatory submission
This label does not authorize IM or SC administration, weight loss, or transfer of IV pharmacokinetics to oral products.
Read the original source36 women · oral trial was null
Randomized placebo-controlled trial
Villani RG et al. International Journal of Sport Nutrition and Exercise Metabolism. 2000. PMID 10861338.
Thirty-six moderately overweight premenopausal women were assigned to oral L-carnitine or placebo while walking four days per week for eight weeks. Among completers, body mass, total fat mass, and resting lipid use did not differ between groups. Five women assigned L-carnitine withdrew because of nausea or diarrhea.
- Participants / model
- 36 moderately overweight premenopausal women
- Treatment
- Oral L-carnitine or placebo with a standardized walking program
- Follow-up
- 8 weeks
- Study design
- Randomized double-blind placebo-controlled trial
Small size, attrition, one population, and an oral exposure limit what this null trial can settle.
Read the original sourceCan the IV half-life be applied to oral supplements or gray-market shots?
The 17.4-hour value is the mean apparent terminal half-life after a specified 20 mg/kg slow IV bolus. The same label reports about 15 percent oral bioavailability, so the IV value does not transfer to oral, intramuscular, or subcutaneous products.
A molecular formula proves chemical identity only when the product actually contains that material. PubChem identifies levocarnitine as C7H15NO3 with molecular weight 161.20 g/mol and CAS 541-15-1. Those facts do not verify the contents or sterility of an unlabeled vial.
US label · IV deficiency treatment
FDA prescribing information
DailyMed. Levocarnitine injection, solution. Updated July 2, 2026.
The current label says FOR INTRAVENOUS USE ONLY and limits treatment to acute or chronic secondary carnitine deficiency from inborn errors and prevention or treatment of deficiency in patients with end-stage renal disease on dialysis. It reports a 17.4-hour mean apparent terminal elimination half-life after a specified 20 mg/kg IV bolus, serious hypersensitivity including anaphylaxis, and postmarketing INR increases with warfarin. It also says clinical outcomes from correcting plasma carnitine in dialysis have not been determined.
- Participants / model
- Patients with qualifying secondary carnitine deficiency or end-stage renal disease undergoing dialysis
- Treatment
- Prescription levocarnitine injection by intravenous administration
- Follow-up
- Label evidence spans single-dose pharmacokinetics and clinical use; it does not define a weight-loss course
- Study design
- Regulatory prescribing information
- Funding
- Manufacturer regulatory submission
This label does not authorize IM or SC administration, weight loss, or transfer of IV pharmacokinetics to oral products.
Read the original sourcePubChem · chemical identity
Government chemical database
National Library of Medicine. PubChem Compound Summary for CID 10917, levocarnitine.
Identifies levocarnitine as the biologically active R stereoisomer of carnitine, with molecular formula C7H15NO3, molecular weight 161.20 g/mol, and CAS Registry Number 541-15-1.
- Participants / model
- Not applicable
- Treatment
- Not applicable
- Follow-up
- Database record
- Study design
- Curated chemical identity record
Identity data do not establish a clinical outcome.
Read the original sourceWhat do the cited studies establish, and what remains unresolved?
The cited evidence includes no direct controlled intramuscular or subcutaneous fat-loss study. Current U.S. labeling supports intravenous administration; the Chinese pilot, trial abstracts, and meta-analysis do not establish fat-loss efficacy after either intramuscular or subcutaneous administration.
US label · IV deficiency treatment
FDA prescribing information
DailyMed. Levocarnitine injection, solution. Updated July 2, 2026.
The current label says FOR INTRAVENOUS USE ONLY and limits treatment to acute or chronic secondary carnitine deficiency from inborn errors and prevention or treatment of deficiency in patients with end-stage renal disease on dialysis. It reports a 17.4-hour mean apparent terminal elimination half-life after a specified 20 mg/kg IV bolus, serious hypersensitivity including anaphylaxis, and postmarketing INR increases with warfarin. It also says clinical outcomes from correcting plasma carnitine in dialysis have not been determined.
- Participants / model
- Patients with qualifying secondary carnitine deficiency or end-stage renal disease undergoing dialysis
- Treatment
- Prescription levocarnitine injection by intravenous administration
- Follow-up
- Label evidence spans single-dose pharmacokinetics and clinical use; it does not define a weight-loss course
- Study design
- Regulatory prescribing information
- Funding
- Manufacturer regulatory submission
This label does not authorize IM or SC administration, weight loss, or transfer of IV pharmacokinetics to oral products.
Read the original sourceFDA approval · dialysis deficiency
FDA approval action
US Food and Drug Administration. NDA 20-182/S-006 approval letter. December 15, 1999.
FDA approved the supplemental indication for prevention and treatment of carnitine deficiency in patients with end-stage renal disease undergoing dialysis. The action concerns Carnitor injection and does not establish an obesity indication or an IM or SC route.
- Participants / model
- Patients with end-stage renal disease undergoing dialysis
- Treatment
- Carnitor levocarnitine injection
- Follow-up
- Regulatory action
- Study design
- FDA supplemental approval letter
Approval scope is indication and product specific.
Read the original source37 trials · modest mean weight change
Systematic review and meta-analysis of randomized trials
Talenezhad N et al. Clinical Nutrition ESPEN. 2020. PMID 32359762.
Across 37 randomized trials with 2,292 participants, L-carnitine reduced body weight by a pooled 1.21 kg versus control (95% CI 0.68 to 1.73 kg lower). BMI and fat mass also moved modestly, while pooled waist circumference and body-fat percentage did not significantly change. Restricting the analysis to higher-quality studies left weight as the only significant anthropometric outcome.
- Participants / model
- Adults across heterogeneous randomized supplementation trials, not one defined obesity population
- Treatment
- L-carnitine supplementation in trial-specific oral or parenteral regimens
- Follow-up
- Varied across included trials
- Study design
- Systematic review and random-effects meta-analysis of 37 randomized controlled trials
- Funding
- Shahid Sadoughi University of Medical Sciences
A pooled mean from heterogeneous trials does not establish a large individual response, a specific injection route, or a gray-market product.
Read the original source36 women · oral trial was null
Randomized placebo-controlled trial
Villani RG et al. International Journal of Sport Nutrition and Exercise Metabolism. 2000. PMID 10861338.
Thirty-six moderately overweight premenopausal women were assigned to oral L-carnitine or placebo while walking four days per week for eight weeks. Among completers, body mass, total fat mass, and resting lipid use did not differ between groups. Five women assigned L-carnitine withdrew because of nausea or diarrhea.
- Participants / model
- 36 moderately overweight premenopausal women
- Treatment
- Oral L-carnitine or placebo with a standardized walking program
- Follow-up
- 8 weeks
- Study design
- Randomized double-blind placebo-controlled trial
Small size, attrition, one population, and an oral exposure limit what this null trial can settle.
Read the original sourceChina pilot · IV plus seven-day fasting
Randomized single-blind placebo-controlled pilot trial
Zhang JJ et al. Scientific Reports. 2014. PMID 25424121; ChiCTR-TNRC-12002835.
At a Guangzhou center, 30 adults with metabolic syndrome were randomized 15 per group during two days of calorie restriction followed by five days of modified fasting. The group receiving 4 g/day IV L-carnitine lost 4.6 kg on average versus 3.2 kg with saline (P=.03) and had a larger waist reduction. Hunger and fatigue ratings also favored L-carnitine.
- Participants / model
- 30 adults with metabolic syndrome at the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
- Treatment
- IV L-carnitine 4 g/day or saline during a seven-day medically supervised calorie-restriction and fasting program
- Follow-up
- 7 days
- Study design
- Randomized, single-blind, placebo-controlled pilot trial
- Funding
- Guangdong provincial and Chinese national research grants reported by authors
The tiny, acute, medically supervised fasting study cannot isolate a durable weight effect, does not test oral use, and does not test intramuscular or subcutaneous injection.
Read the original sourceDialysis trials · primary VO2max analyses negative
Two randomized placebo-controlled trials
Brass EP et al. American Journal of Kidney Diseases. 2001. PMID 11325685.
Two 24-week trials tested IV L-carnitine after dialysis. Study A randomized 28 to 20 mg/kg and 28 to placebo. Study B randomized 32, 30, and 32 to 10, 20, and 40 mg/kg and 33 to placebo. Each study failed its prespecified VO2max comparison. A combined secondary analysis suggested less decline in exercise capacity and improvement in the fatigue domain, while total quality-of-life score and other domains did not improve.
- Participants / model
- Adults receiving maintenance hemodialysis
- Treatment
- IV L-carnitine after dialysis at 10, 20, or 40 mg/kg versus placebo
- Follow-up
- 24 weeks
- Study design
- Two multicenter randomized double-blind placebo-controlled trials
- Funding
- Sigma-Tau Pharmaceuticals
Secondary pooled signals do not convert negative prespecified primary analyses into a proven functional benefit.
Read the original sourceAcute IV study · fuel use, not fat loss
Human metabolic experiment
Natali A et al. Metabolism. 1993. PMID 8492714.
Acute IV carnitine experiments in healthy volunteers measured plasma carnitine and substrate oxidation during lipid infusion and exercise. They addressed short-term fuel selection under experimental conditions, not changes in body fat or body weight.
- Participants / model
- Healthy adult volunteers
- Treatment
- Acute IV L-carnitine under controlled metabolic conditions
- Follow-up
- Acute laboratory experiments
- Study design
- Human metabolic physiology experiments
A substrate-oxidation endpoint is not a clinical fat-loss endpoint.
Read the original sourceIM and SC routes · no controlled fat-loss result
PubMed and trial registry records
PubMed, ClinicalTrials.gov, ChiCTR, and Russian-language records for intramuscular or subcutaneous L-carnitine.
The cited records include no controlled single-ingredient human trial of intramuscular or subcutaneous L-carnitine for fat loss. They instead describe intravenous levocarnitine, intramuscular acetyl-L-carnitine for pain, or multi-ingredient topical products.
- Participants / model
- Human fat-loss studies using intramuscular or subcutaneous levocarnitine
- Treatment
- Intramuscular or subcutaneous single-ingredient L-carnitine
PubChem · chemical identity
Government chemical database
National Library of Medicine. PubChem Compound Summary for CID 10917, levocarnitine.
Identifies levocarnitine as the biologically active R stereoisomer of carnitine, with molecular formula C7H15NO3, molecular weight 161.20 g/mol, and CAS Registry Number 541-15-1.
- Participants / model
- Not applicable
- Treatment
- Not applicable
- Follow-up
- Database record
- Study design
- Curated chemical identity record
Identity data do not establish a clinical outcome.
Read the original sourceStudies and sources
US label · IV deficiency treatment
FDA prescribing information
DailyMed. Levocarnitine injection, solution. Updated July 2, 2026.
The current label says FOR INTRAVENOUS USE ONLY and limits treatment to acute or chronic secondary carnitine deficiency from inborn errors and prevention or treatment of deficiency in patients with end-stage renal disease on dialysis. It reports a 17.4-hour mean apparent terminal elimination half-life after a specified 20 mg/kg IV bolus, serious hypersensitivity including anaphylaxis, and postmarketing INR increases with warfarin. It also says clinical outcomes from correcting plasma carnitine in dialysis have not been determined.
- Participants / model
- Patients with qualifying secondary carnitine deficiency or end-stage renal disease undergoing dialysis
- Treatment
- Prescription levocarnitine injection by intravenous administration
- Follow-up
- Label evidence spans single-dose pharmacokinetics and clinical use; it does not define a weight-loss course
- Study design
- Regulatory prescribing information
- Funding
- Manufacturer regulatory submission
This label does not authorize IM or SC administration, weight loss, or transfer of IV pharmacokinetics to oral products.
Read the original sourceFDA approval · dialysis deficiency
FDA approval action
US Food and Drug Administration. NDA 20-182/S-006 approval letter. December 15, 1999.
FDA approved the supplemental indication for prevention and treatment of carnitine deficiency in patients with end-stage renal disease undergoing dialysis. The action concerns Carnitor injection and does not establish an obesity indication or an IM or SC route.
- Participants / model
- Patients with end-stage renal disease undergoing dialysis
- Treatment
- Carnitor levocarnitine injection
- Follow-up
- Regulatory action
- Study design
- FDA supplemental approval letter
Approval scope is indication and product specific.
Read the original source37 trials · modest mean weight change
Systematic review and meta-analysis of randomized trials
Talenezhad N et al. Clinical Nutrition ESPEN. 2020. PMID 32359762.
Across 37 randomized trials with 2,292 participants, L-carnitine reduced body weight by a pooled 1.21 kg versus control (95% CI 0.68 to 1.73 kg lower). BMI and fat mass also moved modestly, while pooled waist circumference and body-fat percentage did not significantly change. Restricting the analysis to higher-quality studies left weight as the only significant anthropometric outcome.
- Participants / model
- Adults across heterogeneous randomized supplementation trials, not one defined obesity population
- Treatment
- L-carnitine supplementation in trial-specific oral or parenteral regimens
- Follow-up
- Varied across included trials
- Study design
- Systematic review and random-effects meta-analysis of 37 randomized controlled trials
- Funding
- Shahid Sadoughi University of Medical Sciences
A pooled mean from heterogeneous trials does not establish a large individual response, a specific injection route, or a gray-market product.
Read the original source36 women · oral trial was null
Randomized placebo-controlled trial
Villani RG et al. International Journal of Sport Nutrition and Exercise Metabolism. 2000. PMID 10861338.
Thirty-six moderately overweight premenopausal women were assigned to oral L-carnitine or placebo while walking four days per week for eight weeks. Among completers, body mass, total fat mass, and resting lipid use did not differ between groups. Five women assigned L-carnitine withdrew because of nausea or diarrhea.
- Participants / model
- 36 moderately overweight premenopausal women
- Treatment
- Oral L-carnitine or placebo with a standardized walking program
- Follow-up
- 8 weeks
- Study design
- Randomized double-blind placebo-controlled trial
Small size, attrition, one population, and an oral exposure limit what this null trial can settle.
Read the original sourceChina pilot · IV plus seven-day fasting
Randomized single-blind placebo-controlled pilot trial
Zhang JJ et al. Scientific Reports. 2014. PMID 25424121; ChiCTR-TNRC-12002835.
At a Guangzhou center, 30 adults with metabolic syndrome were randomized 15 per group during two days of calorie restriction followed by five days of modified fasting. The group receiving 4 g/day IV L-carnitine lost 4.6 kg on average versus 3.2 kg with saline (P=.03) and had a larger waist reduction. Hunger and fatigue ratings also favored L-carnitine.
- Participants / model
- 30 adults with metabolic syndrome at the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
- Treatment
- IV L-carnitine 4 g/day or saline during a seven-day medically supervised calorie-restriction and fasting program
- Follow-up
- 7 days
- Study design
- Randomized, single-blind, placebo-controlled pilot trial
- Funding
- Guangdong provincial and Chinese national research grants reported by authors
The tiny, acute, medically supervised fasting study cannot isolate a durable weight effect, does not test oral use, and does not test intramuscular or subcutaneous injection.
Read the original sourceDialysis trials · primary VO2max analyses negative
Two randomized placebo-controlled trials
Brass EP et al. American Journal of Kidney Diseases. 2001. PMID 11325685.
Two 24-week trials tested IV L-carnitine after dialysis. Study A randomized 28 to 20 mg/kg and 28 to placebo. Study B randomized 32, 30, and 32 to 10, 20, and 40 mg/kg and 33 to placebo. Each study failed its prespecified VO2max comparison. A combined secondary analysis suggested less decline in exercise capacity and improvement in the fatigue domain, while total quality-of-life score and other domains did not improve.
- Participants / model
- Adults receiving maintenance hemodialysis
- Treatment
- IV L-carnitine after dialysis at 10, 20, or 40 mg/kg versus placebo
- Follow-up
- 24 weeks
- Study design
- Two multicenter randomized double-blind placebo-controlled trials
- Funding
- Sigma-Tau Pharmaceuticals
Secondary pooled signals do not convert negative prespecified primary analyses into a proven functional benefit.
Read the original sourceAcute IV study · fuel use, not fat loss
Human metabolic experiment
Natali A et al. Metabolism. 1993. PMID 8492714.
Acute IV carnitine experiments in healthy volunteers measured plasma carnitine and substrate oxidation during lipid infusion and exercise. They addressed short-term fuel selection under experimental conditions, not changes in body fat or body weight.
- Participants / model
- Healthy adult volunteers
- Treatment
- Acute IV L-carnitine under controlled metabolic conditions
- Follow-up
- Acute laboratory experiments
- Study design
- Human metabolic physiology experiments
A substrate-oxidation endpoint is not a clinical fat-loss endpoint.
Read the original sourceIM and SC routes · no controlled fat-loss result
PubMed and trial registry records
PubMed, ClinicalTrials.gov, ChiCTR, and Russian-language records for intramuscular or subcutaneous L-carnitine.
The cited records include no controlled single-ingredient human trial of intramuscular or subcutaneous L-carnitine for fat loss. They instead describe intravenous levocarnitine, intramuscular acetyl-L-carnitine for pain, or multi-ingredient topical products.
- Participants / model
- Human fat-loss studies using intramuscular or subcutaneous levocarnitine
- Treatment
- Intramuscular or subcutaneous single-ingredient L-carnitine
PubChem · chemical identity
Government chemical database
National Library of Medicine. PubChem Compound Summary for CID 10917, levocarnitine.
Identifies levocarnitine as the biologically active R stereoisomer of carnitine, with molecular formula C7H15NO3, molecular weight 161.20 g/mol, and CAS Registry Number 541-15-1.
- Participants / model
- Not applicable
- Treatment
- Not applicable
- Follow-up
- Database record
- Study design
- Curated chemical identity record
Identity data do not establish a clinical outcome.
Read the original sourceWhy is L-carnitine in A tier?
A reflects an approved prescription identity, an established metabolic role, and randomized human evidence. Approval covers specific deficiency states; weight loss is off-label, and the cited evidence includes no controlled intramuscular or subcutaneous fat-loss trial.
read L-carnitine in the reptides guide, chapter 31: 6 pages, free to read.