tadalafil

Tadalafil is used for erectile dysfunction, lower urinary tract symptoms from benign prostatic hyperplasia, and pulmonary arterial hypertension. Cialis and Adcirca use different regimens, populations, endpoints, and product instructions.

PDE5 inhibitor

Small-molecule prescription medicine
Long-acting PDE5 inhibitor
Cialis and Adcirca have different indications

Why does the same molecule have three different clinical stories?

Cialis is labeled for erectile dysfunction, benign prostatic hyperplasia symptoms, and their combination. Adcirca is labeled for pulmonary arterial hypertension. They contain tadalafil, but use different clinical endpoints and product instructions.

Match the question to the clinical record.
Clinical use	Product record	Outcome to look for
Erectile dysfunction	Cialis	Erection and intercourse-function measures
BPH symptoms	Cialis	Urinary symptom score, not prostate shrinkage
Pulmonary arterial hypertension	Adcirca	Exercise capacity and clinical worsening

Cialis label · ED and BPH

FDA prescribing information

Eli Lilly and Company. Cialis prescribing information.

Defines Cialis indications for erectile dysfunction and BPH symptoms, identifies tadalafil free base, and documents contraindications, interactions, adverse reactions, and emergency warnings.

Participants / model: Adults covered by the erectile-dysfunction and BPH indications
Treatment: Oral tadalafil tablets sold as Cialis
Study design: Regulatory prescribing information

The label contains both as-needed and once-daily clinical contexts; they should not be collapsed into one regimen.

Read the original source

Adcirca label · pulmonary arterial hypertension

FDA prescribing information

United Therapeutics. Adcirca prescribing information.

Defines tadalafil's pulmonary arterial hypertension indication and its product-specific safety, interaction, and exposure information.

Participants / model: Patients with pulmonary arterial hypertension covered by the label
Treatment: Oral tadalafil tablets sold as Adcirca
Study design: Regulatory prescribing information

Adcirca is not the same clinical-use record as Cialis even though both contain tadalafil.

Read the original source

What did the pooled erectile-dysfunction trials show?

Five 12-week randomized trials included 1,112 men with erectile dysfunction of varied causes. In the 20 mg group, the erectile-function score improved by 7.9 points from baseline, 75% of attempts were reported as successful, and 81% reported improved erections versus 35% with placebo.

These results describe as-needed use in a pooled trial population. They do not prove a permanent cure, guarantee a response, or establish safety with contraindicated cardiovascular drugs.

Five pooled ED trials · function outcomes

Integrated analysis of randomized trials

Brock GB et al. Journal of Urology, 2002.

Across 1,112 men in five 12-week trials, tadalafil 20 mg improved the erectile-function score by 7.9 points; 75% of attempts were successful and 81% reported improved erections versus 35% with placebo.

Participants / model: Men age 22 to 82 with mild-to-severe erectile dysfunction of varied causes
Treatment: Fixed-dose as-needed tadalafil groups or placebo
Follow-up: 12 weeks
Study design: Pooled analysis of five randomized, double-blind, placebo-controlled trials
Funding: Industry-sponsored tadalafil development program

PubMed flags a corrected dosing error in the published abstract; this summary follows the corrected record.

Read the original source

Does the 36-hour window mean a 36-hour erection?

No. The Cialis label reports improved erectile function compared with placebo up to 36 hours after an as-needed dose, while tadalafil's mean terminal half-life in healthy people is 17.5 hours. That is a window in which a response may be possible with sexual stimulation, not a continuous erection.

Cialis label · ED and BPH

FDA prescribing information

Eli Lilly and Company. Cialis prescribing information.

Defines Cialis indications for erectile dysfunction and BPH symptoms, identifies tadalafil free base, and documents contraindications, interactions, adverse reactions, and emergency warnings.

Participants / model: Adults covered by the erectile-dysfunction and BPH indications
Treatment: Oral tadalafil tablets sold as Cialis
Study design: Regulatory prescribing information

The label contains both as-needed and once-daily clinical contexts; they should not be collapsed into one regimen.

Read the original source

Does tadalafil shrink the prostate or improve urinary symptoms?

The evidence supports symptom improvement, not prostate shrinkage. In a 12-week randomized trial of 325 men, the International Prostate Symptom Score changed by -5.6 with tadalafil and -3.6 with placebo. Maximum urinary flow and postvoid residual volume did not improve significantly.

BPH trial · symptoms versus flow

Randomized, double-blind trial

Porst H et al. European Urology, 2011.

In 325 men over 12 weeks, symptom scores improved more with tadalafil than placebo, while maximum urinary flow and postvoid residual volume did not improve significantly.

Participants / model: Men with lower urinary tract symptoms suggestive of BPH
Treatment: Tadalafil 5 mg once daily or placebo
Follow-up: 12 weeks
Study design: International randomized, double-blind, placebo-controlled trial
Funding: Eli Lilly

The primary practical result was a patient-reported symptom score, not prostate size or objective relief of obstruction.

Read the original source

What did tadalafil do in pulmonary arterial hypertension?

PHIRST randomized 405 people with pulmonary arterial hypertension for 16 weeks. The 40 mg group improved six-minute walk distance by a placebo-corrected mean of 33 meters. Lower tested groups did not all meet the primary endpoint, which is why the exact trial arm matters.

A walking-distance result in pulmonary arterial hypertension cannot be used to infer an erectile-dysfunction or gym-performance effect.

PHIRST · pulmonary arterial hypertension

Randomized, double-blind trial

Galiè N et al. Circulation, 2009.

In 405 people with pulmonary arterial hypertension, tadalafil 40 mg improved six-minute walk distance by a placebo-corrected mean of 33 meters at 16 weeks.

Participants / model: Treatment-naive patients with pulmonary arterial hypertension or patients receiving background bosentan
Treatment: Placebo or one of four once-daily tadalafil groups
Follow-up: 16 weeks
Study design: Randomized, double-blind, placebo-controlled dose-ranging trial
Funding: Eli Lilly

The primary endpoint was met by the 40 mg group; not every tested group produced the same result.

Read the original source

Do endothelial studies show cardiovascular protection?

They do not establish cardiovascular protection. A 32-person trial reported a larger brachial flow-mediated-dilation value after four weeks of alternate-day tadalafil, but a later trial randomized 89 men and found no between-group benefit in either flow-mediated dilation or erectile-function score among the 82 who completed four weeks.

Both studies measured a short-term ultrasound surrogate. Neither was designed to show fewer heart attacks, strokes, or deaths. Their results conflict.

Small endothelial trial · positive surrogate

Randomized placebo-controlled trial

Rosano GMC et al. European Urology, 2005.

Among 32 men with increased cardiovascular risk, brachial flow-mediated dilation rose from 4.2% to 9.3% after four weeks of alternate-day tadalafil and remained elevated two weeks later; the authors said larger studies were needed to assess clinical implications.

Participants / model: Men with increased cardiovascular risk, with or without erectile dysfunction
Treatment: Tadalafil 20 mg on alternate days or placebo
Follow-up: Four weeks plus two-week follow-up
Study design: Small randomized placebo-controlled surrogate-endpoint trial

Flow-mediated dilation is a vascular surrogate, not a cardiovascular event endpoint.

Read the original source

Endothelial trial · no between-group benefit

Randomized double-blind placebo-controlled trial

Pattanaik S et al. Sexual Medicine, 2019.

Eighty-nine men were randomized and 82 completed four weeks. Changes in erectile-function score and brachial flow-mediated dilation did not differ significantly between tadalafil and placebo; adverse reactions were reported in 14 versus 5 participants.

Participants / model: Men with erectile dysfunction and baseline flow-mediated dilation below 15%
Treatment: Low-dose tadalafil or matching placebo
Follow-up: Four weeks
Study design: Randomized, double-blind, placebo-controlled trial

Both groups improved from baseline, making the between-group result the relevant comparison.

Read the original source

Does the dementia association prove that tadalafil prevents Alzheimer disease?

No. A UK health-record cohort followed 269,725 men with newly diagnosed erectile dysfunction and found fewer Alzheimer diagnoses among initiators of the PDE5-inhibitor class, but the association weakened to a non-significant hazard ratio of 0.93 after a three-year lag. The paper did not find strong drug-specific evidence for tadalafil.

Prescription patterns, health behavior, prodromal disease, and other confounding can create an association in records. A randomized prevention trial would be needed before this becomes a treatment claim.

UK record cohort · association, not prevention

Observational cohort study

Adesuyan M et al. Neurology, 2024.

Among 269,725 men with a new erectile-dysfunction diagnosis, PDE5-inhibitor initiation was associated with fewer Alzheimer diagnoses over median 5.1 years, but the three-year-lag analysis was not significant and drug-specific evidence for tadalafil was not strong.

Participants / model: UK men age 40 or older with newly diagnosed erectile dysfunction
Treatment: PDE5-inhibitor prescription initiation versus nonuse
Follow-up: Median 5.1 years of electronic-record follow-up
Study design: Retrospective observational cohort with time-varying exposure
Funding: UK Medical Research Council grant listed by PubMed

This class-level association cannot establish causation or prove a tadalafil prevention effect.

Read the original source

Did tadalafil preserve walking ability in Duchenne muscular dystrophy?

No. A phase 3 trial randomized 331 boys age 7 to 14 who were taking corticosteroids. At 48 weeks, six-minute-walk distance declined by 51.0 meters with placebo, 64.7 meters with the lower tadalafil group, and 59.1 meters with the higher group. Neither tadalafil group beat placebo, and secondary outcomes were also negative.

A prespecified exploratory upper-limb signal in one older subgroup was hypothesis-generating. It does not reverse the negative primary and secondary results.

Duchenne trial · ambulatory endpoint failed

Phase 3 randomized placebo-controlled trial

Victor RG et al. Neurology, 2017.

In 331 boys age 7 to 14 taking corticosteroids, tadalafil did not reduce the 48-week decline in six-minute-walk distance and did not improve secondary outcomes.

Participants / model: Ambulatory boys with Duchenne muscular dystrophy, age 7 to 14, taking corticosteroids
Treatment: Two once-daily tadalafil groups or placebo
Follow-up: 48 weeks
Study design: Phase 3 randomized placebo-controlled trial
Funding: Eli Lilly was involved; company authors are listed

The paper classified this as Class I evidence that tadalafil did not slow ambulatory decline in the studied population.

Read the original source

Did daily tadalafil impair semen measures in a controlled trial?

Two linked six-month trials randomized 421 men age 45 or older with normal baseline semen criteria to placebo or daily tadalafil. They found no adverse effect on sperm concentration, total count, motility, morphology, testosterone, LH, or FSH.

The selected population showed no adverse change in the measured semen and hormone outcomes. The trial did not measure fertility, pregnancy, or offspring outcomes and did not test unapproved tadalafil analogs.

Semen study · selected older men

Two randomized placebo-controlled trials

Hellstrom WJG et al. Journal of Urology, 2003.

Across 421 men age 45 or older with qualifying baseline semen measures, six months of daily tadalafil did not adversely affect sperm concentration, count, motility, morphology, testosterone, LH, or FSH.

Participants / model: Healthy men or men with mild erectile dysfunction, age 45 or older, meeting baseline semen criteria
Treatment: Daily tadalafil 10 mg or 20 mg versus placebo in two studies
Follow-up: Six months
Study design: Two randomized placebo-controlled clinical trials
Funding: Industry tadalafil development program

The study measured semen and reproductive-hormone laboratory outcomes, not conception or live birth.

Read the original source

Which interactions can become dangerous?

Nitrates and guanylate-cyclase stimulators such as riociguat are contraindicated because blood pressure can fall dangerously. Alpha blockers, antihypertensives, substantial alcohol intake, and strong CYP3A4 inhibitors or inducers also change risk or exposure.

Common effects include headache, indigestion, back pain, muscle aches, flushing, and nasal congestion.
Urgent label warnings cover an erection lasting more than four hours and sudden vision or hearing loss.
Sexual activity itself can be unsafe for some people with cardiovascular disease, independent of the pill.

Cialis label · ED and BPH

FDA prescribing information

Eli Lilly and Company. Cialis prescribing information.

Defines Cialis indications for erectile dysfunction and BPH symptoms, identifies tadalafil free base, and documents contraindications, interactions, adverse reactions, and emergency warnings.

Participants / model: Adults covered by the erectile-dysfunction and BPH indications
Treatment: Oral tadalafil tablets sold as Cialis
Study design: Regulatory prescribing information

The label contains both as-needed and once-daily clinical contexts; they should not be collapsed into one regimen.

Read the original source

Adcirca label · pulmonary arterial hypertension

FDA prescribing information

United Therapeutics. Adcirca prescribing information.

Defines tadalafil's pulmonary arterial hypertension indication and its product-specific safety, interaction, and exposure information.

Participants / model: Patients with pulmonary arterial hypertension covered by the label
Treatment: Oral tadalafil tablets sold as Adcirca
Study design: Regulatory prescribing information

Adcirca is not the same clinical-use record as Cialis even though both contain tadalafil.

Read the original source

Are tadalafil citrate and aminotadalafil the same thing?

The approved active ingredient is tadalafil free base. Aminotadalafil is a different, unapproved molecule reported in adulterated products. A seller's use of the phrase tadalafil citrate does not create an FDA-approved salt form or transfer tadalafil trial evidence to that material.

Tadalafil inhibits PDE5, allowing cyclic GMP signaling to persist in responsive smooth muscle. Sexual stimulation is still required for the erectile response, and pulmonary vascular effects belong to a different disease context.

Cialis label · ED and BPH

FDA prescribing information

Eli Lilly and Company. Cialis prescribing information.

Defines Cialis indications for erectile dysfunction and BPH symptoms, identifies tadalafil free base, and documents contraindications, interactions, adverse reactions, and emergency warnings.

Participants / model: Adults covered by the erectile-dysfunction and BPH indications
Treatment: Oral tadalafil tablets sold as Cialis
Study design: Regulatory prescribing information

The label contains both as-needed and once-daily clinical contexts; they should not be collapsed into one regimen.

Read the original source

Adcirca label · pulmonary arterial hypertension

FDA prescribing information

United Therapeutics. Adcirca prescribing information.

Defines tadalafil's pulmonary arterial hypertension indication and its product-specific safety, interaction, and exposure information.

Participants / model: Patients with pulmonary arterial hypertension covered by the label
Treatment: Oral tadalafil tablets sold as Adcirca
Study design: Regulatory prescribing information

Adcirca is not the same clinical-use record as Cialis even though both contain tadalafil.

Read the original source

Studies and sources

Cialis label · ED and BPH

FDA prescribing information

Eli Lilly and Company. Cialis prescribing information.

Defines Cialis indications for erectile dysfunction and BPH symptoms, identifies tadalafil free base, and documents contraindications, interactions, adverse reactions, and emergency warnings.

Participants / model: Adults covered by the erectile-dysfunction and BPH indications
Treatment: Oral tadalafil tablets sold as Cialis
Study design: Regulatory prescribing information

The label contains both as-needed and once-daily clinical contexts; they should not be collapsed into one regimen.

Read the original source

Adcirca label · pulmonary arterial hypertension

FDA prescribing information

United Therapeutics. Adcirca prescribing information.

Defines tadalafil's pulmonary arterial hypertension indication and its product-specific safety, interaction, and exposure information.

Participants / model: Patients with pulmonary arterial hypertension covered by the label
Treatment: Oral tadalafil tablets sold as Adcirca
Study design: Regulatory prescribing information

Adcirca is not the same clinical-use record as Cialis even though both contain tadalafil.

Read the original source

Five pooled ED trials · function outcomes

Integrated analysis of randomized trials

Brock GB et al. Journal of Urology, 2002.

Across 1,112 men in five 12-week trials, tadalafil 20 mg improved the erectile-function score by 7.9 points; 75% of attempts were successful and 81% reported improved erections versus 35% with placebo.

Participants / model: Men age 22 to 82 with mild-to-severe erectile dysfunction of varied causes
Treatment: Fixed-dose as-needed tadalafil groups or placebo
Follow-up: 12 weeks
Study design: Pooled analysis of five randomized, double-blind, placebo-controlled trials
Funding: Industry-sponsored tadalafil development program

PubMed flags a corrected dosing error in the published abstract; this summary follows the corrected record.

Read the original source

BPH trial · symptoms versus flow

Randomized, double-blind trial

Porst H et al. European Urology, 2011.

In 325 men over 12 weeks, symptom scores improved more with tadalafil than placebo, while maximum urinary flow and postvoid residual volume did not improve significantly.

Participants / model: Men with lower urinary tract symptoms suggestive of BPH
Treatment: Tadalafil 5 mg once daily or placebo
Follow-up: 12 weeks
Study design: International randomized, double-blind, placebo-controlled trial
Funding: Eli Lilly

The primary practical result was a patient-reported symptom score, not prostate size or objective relief of obstruction.

Read the original source

PHIRST · pulmonary arterial hypertension

Randomized, double-blind trial

Galiè N et al. Circulation, 2009.

In 405 people with pulmonary arterial hypertension, tadalafil 40 mg improved six-minute walk distance by a placebo-corrected mean of 33 meters at 16 weeks.

Participants / model: Treatment-naive patients with pulmonary arterial hypertension or patients receiving background bosentan
Treatment: Placebo or one of four once-daily tadalafil groups
Follow-up: 16 weeks
Study design: Randomized, double-blind, placebo-controlled dose-ranging trial
Funding: Eli Lilly

The primary endpoint was met by the 40 mg group; not every tested group produced the same result.

Read the original source

Small endothelial trial · positive surrogate

Randomized placebo-controlled trial

Rosano GMC et al. European Urology, 2005.

Among 32 men with increased cardiovascular risk, brachial flow-mediated dilation rose from 4.2% to 9.3% after four weeks of alternate-day tadalafil and remained elevated two weeks later; the authors said larger studies were needed to assess clinical implications.

Participants / model: Men with increased cardiovascular risk, with or without erectile dysfunction
Treatment: Tadalafil 20 mg on alternate days or placebo
Follow-up: Four weeks plus two-week follow-up
Study design: Small randomized placebo-controlled surrogate-endpoint trial

Flow-mediated dilation is a vascular surrogate, not a cardiovascular event endpoint.

Read the original source

Endothelial trial · no between-group benefit

Randomized double-blind placebo-controlled trial

Pattanaik S et al. Sexual Medicine, 2019.

Eighty-nine men were randomized and 82 completed four weeks. Changes in erectile-function score and brachial flow-mediated dilation did not differ significantly between tadalafil and placebo; adverse reactions were reported in 14 versus 5 participants.

Participants / model: Men with erectile dysfunction and baseline flow-mediated dilation below 15%
Treatment: Low-dose tadalafil or matching placebo
Follow-up: Four weeks
Study design: Randomized, double-blind, placebo-controlled trial

Both groups improved from baseline, making the between-group result the relevant comparison.

Read the original source

UK record cohort · association, not prevention

Observational cohort study

Adesuyan M et al. Neurology, 2024.

Among 269,725 men with a new erectile-dysfunction diagnosis, PDE5-inhibitor initiation was associated with fewer Alzheimer diagnoses over median 5.1 years, but the three-year-lag analysis was not significant and drug-specific evidence for tadalafil was not strong.

Participants / model: UK men age 40 or older with newly diagnosed erectile dysfunction
Treatment: PDE5-inhibitor prescription initiation versus nonuse
Follow-up: Median 5.1 years of electronic-record follow-up
Study design: Retrospective observational cohort with time-varying exposure
Funding: UK Medical Research Council grant listed by PubMed

This class-level association cannot establish causation or prove a tadalafil prevention effect.

Read the original source

Duchenne trial · ambulatory endpoint failed

Phase 3 randomized placebo-controlled trial

Victor RG et al. Neurology, 2017.

In 331 boys age 7 to 14 taking corticosteroids, tadalafil did not reduce the 48-week decline in six-minute-walk distance and did not improve secondary outcomes.

Participants / model: Ambulatory boys with Duchenne muscular dystrophy, age 7 to 14, taking corticosteroids
Treatment: Two once-daily tadalafil groups or placebo
Follow-up: 48 weeks
Study design: Phase 3 randomized placebo-controlled trial
Funding: Eli Lilly was involved; company authors are listed

The paper classified this as Class I evidence that tadalafil did not slow ambulatory decline in the studied population.

Read the original source

Semen study · selected older men

Two randomized placebo-controlled trials

Hellstrom WJG et al. Journal of Urology, 2003.

Across 421 men age 45 or older with qualifying baseline semen measures, six months of daily tadalafil did not adversely affect sperm concentration, count, motility, morphology, testosterone, LH, or FSH.

Participants / model: Healthy men or men with mild erectile dysfunction, age 45 or older, meeting baseline semen criteria
Treatment: Daily tadalafil 10 mg or 20 mg versus placebo in two studies
Follow-up: Six months
Study design: Two randomized placebo-controlled clinical trials
Funding: Industry tadalafil development program

The study measured semen and reproductive-hormone laboratory outcomes, not conception or live birth.

Read the original source

Why is tadalafil in S tier?

S reflects multiple approvals and randomized human evidence. The three indications use distinct endpoints and regimens, and the evidence does not transfer to unapproved analogs.