Oxandrolone
Oxandrolone can increase lean mass and strength, but it can also injure the liver and worsen cholesterol. US approvals for the drug were withdrawn in 2023.
Oral anabolic-androgenic steroid
- Also called Anavar
- US approvals withdrawn
What is Anavar, and is it still FDA-approved?
Anavar is a name for oxandrolone, an oral anabolic-androgenic steroid. Its US approvals were withdrawn in 2023.
The historical medical record includes treatment of weight loss and catabolic illness. A seller using the Anavar name does not make a product equivalent to the former prescription tablets.
FDA · why approval was withdrawn
Regulatory determination
FDA, Federal Register, September 13, 2023.
FDA determined that Oxandrin was withdrawn for reasons of safety or effectiveness. The notice describes serious liver and lipid risks and the agency’s concerns about efficacy; it follows withdrawal of approval in June 2023.
Read the original sourceOxandrin label · risks and half-life
Historical prescribing information
Oxandrin historical prescribing information.
The archived label reports serious hepatic and lipid warnings, androgenic effects and hormone suppression. Mean oral half-lives were 10.4 hours in younger volunteers and 13.3 hours in older subjects.
US approvals were withdrawn in 2023; this is the former prescribing information.
Read the original sourceWhat did studies actually find for muscle, strength and fat?
A 12-week trial in 32 men aged 60 to 87 found increased lean mass and strength and reduced fat. It did not study trained bodybuilders.
| Measure | Oxandrolone group |
|---|---|
| Lean mass | +3.0 kg |
| Total body water | +2.9 kg |
| Total fat | −1.9 kg |
| Trunk fat | −1.3 kg |
32 men aged 60 to 87 were randomized to oxandrolone or placebo. These are changes in the treated group; the reported between-group differences favored treatment.
Older-men trial · body composition and stopping
Randomized placebo-controlled trial
Journal of applied physiology (Bethesda, Md. : 1985). PMID 14578370.
In 32 men aged 60 to 87, oxandrolone increased lean mass by 3.0 kg, total body water by 2.9 kg and thigh muscle area, while total fat fell 1.9 kg. Strength also improved. Twelve weeks after stopping, lean-mass and strength gains were no longer above baseline.
- Treatment
- 20 mg daily or placebo for 12 weeks.
These were older men, not trained bodybuilders. Fat loss was largely maintained after stopping; appearance was not assessed.
Read the original sourceDoes it create a dry, hard look?
The study did not score appearance, and body water increased. More lean tissue and less fat may change appearance, but “dry” is not evidence that oxandrolone removes water. Lean mass is not the same measurement as pure muscle protein.
Older-men trial · body composition and stopping
Randomized placebo-controlled trial
Journal of applied physiology (Bethesda, Md. : 1985). PMID 14578370.
In 32 men aged 60 to 87, oxandrolone increased lean mass by 3.0 kg, total body water by 2.9 kg and thigh muscle area, while total fat fell 1.9 kg. Strength also improved. Twelve weeks after stopping, lean-mass and strength gains were no longer above baseline.
- Treatment
- 20 mg daily or placebo for 12 weeks.
These were older men, not trained bodybuilders. Fat loss was largely maintained after stopping; appearance was not assessed.
Read the original sourceWhat does the safety record show?
Oxandrolone can injure the liver, worsen cholesterol, suppress reproductive hormones and cause virilization.
FDA’s withdrawal determination specifically discusses blood-filled liver lesions, liver tumors and lipid changes linked to cardiovascular risk. In the HIV trial, liver enzymes and LDL increased while HDL and gonadal hormones decreased.
FDA · why approval was withdrawn
Regulatory determination
FDA, Federal Register, September 13, 2023.
FDA determined that Oxandrin was withdrawn for reasons of safety or effectiveness. The notice describes serious liver and lipid risks and the agency’s concerns about efficacy; it follows withdrawal of approval in June 2023.
Read the original sourceHIV weight-loss trial · benefit and harm
Randomized placebo-controlled trial
Journal of acquired immune deficiency syndromes (1999). PMID 16540931.
In 262 men, only the 40 mg group’s weight gain and the 40 and 80 mg groups’ body-cell-mass gains exceeded placebo at 12 weeks. Testosterone and gonadotropins fell; liver enzymes and LDL rose, while HDL fell.
- Participants / model
- Men with HIV-associated weight loss.
- Treatment
- 20, 40 or 80 mg daily, or placebo.
Weight increased in every group, including placebo. The within-group gain is not the treatment effect.
Read the original sourceWhat about women or adolescents?
Pregnancy is contraindicated in the historical label. Androgenic effects include menstrual changes, excess hair and voice deepening. In children, accelerated bone maturation can compromise adult height.
Oxandrin label · risks and half-life
Historical prescribing information
Oxandrin historical prescribing information.
The archived label reports serious hepatic and lipid warnings, androgenic effects and hormone suppression. Mean oral half-lives were 10.4 hours in younger volunteers and 13.3 hours in older subjects.
US approvals were withdrawn in 2023; this is the former prescribing information.
Read the original sourceDoes the newer animal study settle safety in women?
No. A 2026 female-rat training experiment found tissue injury without a significant strength gain. It adds animal toxicology, not a human adverse-event rate or a safe exposure for women.
Female-rat study · training and tissue injury
Animal experiment
The Journal of steroid biochemistry and molecular biology. PMID 41620041.
In 24 trained female rats, oxandrolone did not significantly improve muscle mass or strength, while tissue injury and increased liver lipid peroxidation were observed.
Rat findings cannot quantify risk or expected results in women.
Read the original sourceWhat did studies in burns and HIV-associated weight loss find?
The burn trial found a shorter hospital stay, and the HIV trial reported larger gains on some active-dose outcomes. Both involved severe catabolic illness rather than athletic performance in healthy people.
The burn study stopped enrollment early. In the HIV trial, placebo recipients also gained weight, and only some active-dose outcomes were significantly better than placebo.
Severe-burn trial · hospital stay
Randomized double-blind trial
Journal of burn care & research : official publication of the American Burn Association. PMID 16566555.
In 81 adults with burns covering 20% to 60% of the body, mean hospital stay was 31.6 days with oxandrolone and 43.3 with placebo. Enrollment stopped early after a planned interim analysis.
- Treatment
- 10 mg every 12 hours during inpatient care.
Severe-burn recovery does not establish athletic benefit. The abstract recommends monitoring hepatic transaminases but does not supply the detailed liver-event counts.
Read the original sourceHIV weight-loss trial · benefit and harm
Randomized placebo-controlled trial
Journal of acquired immune deficiency syndromes (1999). PMID 16540931.
In 262 men, only the 40 mg group’s weight gain and the 40 and 80 mg groups’ body-cell-mass gains exceeded placebo at 12 weeks. Testosterone and gonadotropins fell; liver enzymes and LDL rose, while HDL fell.
- Participants / model
- Men with HIV-associated weight loss.
- Treatment
- 20, 40 or 80 mg daily, or placebo.
Weight increased in every group, including placebo. The within-group gain is not the treatment effect.
Read the original sourceHow can it increase muscle tissue?
Oxandrolone activates androgen pathways. A small human biopsy study supports increased muscle protein synthesis.
The six-man experiment measured protein turnover over five days. It does not show that 44% more synthesis produces 44% more muscle, and it does not establish the safety of prolonged use.
Muscle-biopsy study · protein synthesis
Human before-and-after mechanistic study
The Journal of clinical endocrinology and metabolism. PMID 10443664.
Six young men were studied before and after five days of oxandrolone. Muscle protein fractional synthesis increased 44%; protein breakdown did not change.
- Treatment
- 15 mg daily in the study.
A short tracer and biopsy experiment cannot establish long-term muscle gain, appearance or safety.
Read the original sourceDo the gains stay after stopping?
In the older-men trial, the lean-mass and strength gains were no longer above baseline 12 weeks after treatment ended. Much of the fat reduction remained.
Natural hormone production can be suppressed during treatment; the HIV trial documented reduced testosterone, LH and FSH.
Older-men trial · body composition and stopping
Randomized placebo-controlled trial
Journal of applied physiology (Bethesda, Md. : 1985). PMID 14578370.
In 32 men aged 60 to 87, oxandrolone increased lean mass by 3.0 kg, total body water by 2.9 kg and thigh muscle area, while total fat fell 1.9 kg. Strength also improved. Twelve weeks after stopping, lean-mass and strength gains were no longer above baseline.
- Treatment
- 20 mg daily or placebo for 12 weeks.
These were older men, not trained bodybuilders. Fat loss was largely maintained after stopping; appearance was not assessed.
Read the original sourceHIV weight-loss trial · benefit and harm
Randomized placebo-controlled trial
Journal of acquired immune deficiency syndromes (1999). PMID 16540931.
In 262 men, only the 40 mg group’s weight gain and the 40 and 80 mg groups’ body-cell-mass gains exceeded placebo at 12 weeks. Testosterone and gonadotropins fell; liver enzymes and LDL rose, while HDL fell.
- Participants / model
- Men with HIV-associated weight loss.
- Treatment
- 20, 40 or 80 mg daily, or placebo.
Weight increased in every group, including placebo. The within-group gain is not the treatment effect.
Read the original sourceWhat is the human half-life?
The archived Oxandrin label reports an average of 10.4 hours in younger volunteers and 13.3 hours in older adults.
These figures describe elimination of oral oxandrolone. They do not measure how long hormone suppression or liver effects last.
Oxandrin label · risks and half-life
Historical prescribing information
Oxandrin historical prescribing information.
The archived label reports serious hepatic and lipid warnings, androgenic effects and hormone suppression. Mean oral half-lives were 10.4 hours in younger volunteers and 13.3 hours in older subjects.
US approvals were withdrawn in 2023; this is the former prescribing information.
Read the original sourceWhich interaction is particularly important?
Oxandrolone can strongly increase warfarin’s anticoagulant effect. Starting or stopping it can therefore change bleeding risk.
The interaction was measured in volunteers, with bleeding observed. People taking warfarin need prescriber-led anticoagulation monitoring when oxandrolone is started or stopped.
Warfarin interaction · bleeding risk
Historical label interaction study
Oxandrin historical prescribing information.
In 15 volunteers taking warfarin, oxandrolone substantially increased warfarin exposure. Blood in urine occurred in nine participants and gum bleeding in one. The label calls for close anticoagulation monitoring when oxandrolone starts or stops.
The study’s warfarin dose reductions are not instructions for self-adjustment.
Read the original sourceStudies and sources
FDA · why approval was withdrawn
Regulatory determination
FDA, Federal Register, September 13, 2023.
FDA determined that Oxandrin was withdrawn for reasons of safety or effectiveness. The notice describes serious liver and lipid risks and the agency’s concerns about efficacy; it follows withdrawal of approval in June 2023.
Read the original sourceOxandrin label · risks and half-life
Historical prescribing information
Oxandrin historical prescribing information.
The archived label reports serious hepatic and lipid warnings, androgenic effects and hormone suppression. Mean oral half-lives were 10.4 hours in younger volunteers and 13.3 hours in older subjects.
US approvals were withdrawn in 2023; this is the former prescribing information.
Read the original sourceOlder-men trial · body composition and stopping
Randomized placebo-controlled trial
Journal of applied physiology (Bethesda, Md. : 1985). PMID 14578370.
In 32 men aged 60 to 87, oxandrolone increased lean mass by 3.0 kg, total body water by 2.9 kg and thigh muscle area, while total fat fell 1.9 kg. Strength also improved. Twelve weeks after stopping, lean-mass and strength gains were no longer above baseline.
- Treatment
- 20 mg daily or placebo for 12 weeks.
These were older men, not trained bodybuilders. Fat loss was largely maintained after stopping; appearance was not assessed.
Read the original sourceHIV weight-loss trial · benefit and harm
Randomized placebo-controlled trial
Journal of acquired immune deficiency syndromes (1999). PMID 16540931.
In 262 men, only the 40 mg group’s weight gain and the 40 and 80 mg groups’ body-cell-mass gains exceeded placebo at 12 weeks. Testosterone and gonadotropins fell; liver enzymes and LDL rose, while HDL fell.
- Participants / model
- Men with HIV-associated weight loss.
- Treatment
- 20, 40 or 80 mg daily, or placebo.
Weight increased in every group, including placebo. The within-group gain is not the treatment effect.
Read the original sourceSevere-burn trial · hospital stay
Randomized double-blind trial
Journal of burn care & research : official publication of the American Burn Association. PMID 16566555.
In 81 adults with burns covering 20% to 60% of the body, mean hospital stay was 31.6 days with oxandrolone and 43.3 with placebo. Enrollment stopped early after a planned interim analysis.
- Treatment
- 10 mg every 12 hours during inpatient care.
Severe-burn recovery does not establish athletic benefit. The abstract recommends monitoring hepatic transaminases but does not supply the detailed liver-event counts.
Read the original sourceMuscle-biopsy study · protein synthesis
Human before-and-after mechanistic study
The Journal of clinical endocrinology and metabolism. PMID 10443664.
Six young men were studied before and after five days of oxandrolone. Muscle protein fractional synthesis increased 44%; protein breakdown did not change.
- Treatment
- 15 mg daily in the study.
A short tracer and biopsy experiment cannot establish long-term muscle gain, appearance or safety.
Read the original sourceFemale-rat study · training and tissue injury
Animal experiment
The Journal of steroid biochemistry and molecular biology. PMID 41620041.
In 24 trained female rats, oxandrolone did not significantly improve muscle mass or strength, while tissue injury and increased liver lipid peroxidation were observed.
Rat findings cannot quantify risk or expected results in women.
Read the original sourceWarfarin interaction · bleeding risk
Historical label interaction study
Oxandrin historical prescribing information.
In 15 volunteers taking warfarin, oxandrolone substantially increased warfarin exposure. Blood in urine occurred in nine participants and gum bleeding in one. The label calls for close anticoagulation monitoring when oxandrolone starts or stops.
The study’s warfarin dose reductions are not instructions for self-adjustment.
Read the original sourceWhy is Oxandrolone in S tier?
S tier reflects controlled human studies of lean mass, strength and recovery from catabolic illness. Those studies also documented liver-enzyme, cholesterol and hormone changes. US approval was withdrawn in 2023.