Biohacking Kompakt

Peptide & Experimental

Tadalafil

Phosphodiesterase-5 inhibitor (PDE5 inhibitor), prescription-only medicine · Cialis, Adcirca, PDE5 inhibitor

Tadalafil improves two conditions at once: erectile dysfunction and the symptoms of benign prostatic enlargement. The long-acting PDE5 inhibitor is approved for both, and both are backed by meta-analyses of randomized trials. Where this effect reaches its limit on objectively measured values is set out further below.

What tadalafil is

Tadalafil is a prescription-only phosphodiesterase-5 inhibitor, approved in the European Union as Cialis for erectile dysfunction and for symptoms of benign prostatic enlargement. Its long duration of action is characteristic and allows low-dose daily use.

What is rated is the state of knowledge. For both indications, there are phase III programs and meta-analyses, plus decades of post-marketing surveillance. The evidence is dense, including the negative partial findings.

How it works

Tadalafil inhibits the enzyme PDE5, which breaks down the messenger cGMP. Via the nitric oxide-cGMP pathway, the smooth muscle of blood vessels and hollow organs relaxes - in the erectile tissue, but also in the prostate and bladder neck, which explains the second indication.

Further areas of use are often inferred from the mechanism. Such inferences are hypotheses; what counts is what controlled trials have measured.

The fact check on prostate symptoms

This is where the decisive distinction lies. The International Prostate Symptom Score, IPSS for short, is a questionnaire: it records how strongly those affected feel impaired. Maximum urinary flow is measured with a device.

On tadalafil, the questionnaire score improves markedly. Measured urinary flow barely changes across all doses. Both together are the finding, and it should not be shortened to the first half.

What is well supported

  • Two indications, both approved. Cialis has been approved in the EU for erectile dysfunction since November 12, 2002, and additionally for symptoms of benign prostatic enlargement since 2012. A treatment benefit is thus officially recognized for both conditions.
  • Both conditions improve in the same trials. The meta-analysis by Wang 2018 of 13 randomized trials with 3,973 people and 12 weeks of treatment shows an SMD of minus 2.02 (minus 2.52 to minus 1.53) for the IPSS symptom score and an SMD of 5.18 (4.13 to 6.23) for erectile function in the IIEF-EF domain, each p less than 0.00001. The BPH Impact Index improved by an SMD of minus 0.58 (minus 0.84 to minus 0.33).
  • Independently confirmed. Dong 2013, across 8 randomized trials, arrives at the same direction and magnitude: IPSS minus 2.19 points and IIEF plus 4.66 points, each p less than 0.00001. In a separate phase 3 trial with 909 men over 12 weeks (Zhang 2019), the IPSS improved by 5.49 points and the IIEF-EF domain by 5.24 points, each p less than 0.001.
  • The side-effect profile has been measured. In Dong 2013, serious side effects occurred exactly as often as on placebo, with an RR of 1.00 (p = 1.00). The comparison with sildenafil across 16 studies (Gong 2017) shows similar efficacy and a similar overall rate of side effects, with a shift toward myalgia and back pain and away from flushing. Discontinuations because of side effects, however, were more frequent than on placebo (OR 1.79, 1.12 to 2.85, p = 0.01).

What the studies show

Meta-analysis on symptoms and erectile function

Wang 2018 (Low Urin Tract Symptoms) pooled 13 randomized trials with 3,973 people, tadalafil 5 mg daily versus placebo over 12 weeks in lower urinary tract symptoms plus erectile dysfunction. The IPSS improved with a standardized mean difference of -2.02 (-2.52 to -1.53; p<0.00001), erectile function with 5.18 (4.13 to 6.23), the BPH Impact Index with -0.58 (-0.84 to -0.33). Discontinuations because of side effects were more frequent, odds ratio 1.79 (1.12 to 2.85; p=0.01).

Urinary flow: the limiting finding

Dong 2013 (Urol Int) analyzed 8 randomized trials on lower urinary tract symptoms with prostatic enlargement. The IPSS fell by 2.19 points (p<0.00001), erectile function rose by 4.66 points (p<0.00001). Maximum urinary flow improved by only 0.26 ml/s across all doses and, with p=0.14, missed significance; only for 5 mg was there a gain of 0.63 ml/s (p=0.04). Serious side effects: relative risk 1.00 (p=1.00).

Phase 3 trial with placebo and tamsulosin arms

Zhang 2019 (Int J Urol) randomized 909 Asian men in a phase 3 trial over 12 weeks to placebo, tadalafil 5 mg or tamsulosin. The IPSS fell by 5.49 points on tadalafil and by 4.08 points on placebo; erectile function rose by 5.24 versus 1.88 points (each p<0.001). The abstract does not report a direct comparison with tamsulosin.

Tadalafil versus sildenafil

Gong 2017 (Int Urol Nephrol) compared tadalafil and sildenafil in 16 studies. Efficacy and the overall rate of side effects were similar, but the profile differed: on tadalafil, muscle and back pain were more frequent and facial flushing less frequent.

Where the data stop

  • An objective improvement in urinary flow. The symptom score improves markedly, but the maximum urinary flow measured with a device improves by only 0.26 ml/s across all doses and thus not significantly (p=0.14). This gap is usually passed over.
  • Halting prostatic enlargement. The available meta-analysis explicitly does not show that progression is slowed or the need for surgery reduced. Over 12 weeks, only symptom and function scores were measured, that is, surrogate markers instead of the course of disease.
  • An independent blood-pressure-lowering therapeutic benefit. This is not verified. The contraindication with nitrates and guanylate cyclase stimulators underlines the vascular effect but does not prove a treatment benefit.
  • Effects on the brain and cognition. A neuroprotective effect or one that promotes blood flow in the brain is being studied but is not convincingly shown in humans. There are no approval data for it.

Status, approval and legal

Cialis has been approved in the EU for erectile dysfunction since November 12, 2002, and additionally for symptoms of benign prostatic enlargement since 2012. The drug is prescription-only.

The Cialis approval covers two indications; as Adcirca, tadalafil is additionally approved for pulmonary arterial hypertension. Use as a general vascular or longevity drug is not covered by any approval, and there are no approval trials for it.

Safety

In Dong 2013, serious side effects were no more frequent than on placebo, relative risk 1.00 (p=1.00). In Wang 2018, by contrast, discontinuations because of side effects were more frequent, odds ratio 1.79. Compared with sildenafil, muscle and back pain predominate, and facial flushing is less frequent.

The hard rule concerns combination: concomitant use with nitrates and guanylate cyclase stimulators is contraindicated according to the approval - not a precaution but a contraindication.

BK-Score Well supported

Human evidence10
Mechanism9
Safety data9
Hype gap7
Track record of use10

One of the best-supported substances in the entire collection: approved since 2002 for erectile dysfunction, since 2012 also for benign prostatic enlargement, and as Adcirca additionally for pulmonary arterial hypertension, each on the basis of extensive phase III programs. PDE5 inhibition is quantitatively understood in humans. More than two decades of pharmacovigilance provide a clear warning profile – nitrate interaction, visual disturbances, priapism. The deduction concerns only the fringe marketing as a general vascular longevity drug, for which there are no approval trials.

The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless. “Track record of use 9” means used long and widely – that is not proof of efficacy.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about Tadalafil

Does tadalafil really help with prostate symptoms?

The symptom questionnaire improves markedly. Across 13 randomized trials with 3,973 people, the IPSS fell with a standardized mean difference of minus 2.02, and in a phase 3 trial with 909 men by 5.49 points. The objectively measured maximum urinary flow, by contrast, barely improved. That very gap belongs in the answer.

Does tadalafil improve urinary flow?

No, not measurably. In a meta-analysis of eight randomized trials, maximum urinary flow rose by 0.26 ml/s across all doses and, with p = 0.14, missed statistical significance. Only for the 5 mg dose was there a barely significant gain of 0.63 ml/s.

Does tadalafil work better than placebo for prostate symptoms?

Yes. In a phase 3 trial with 909 Asian men, the symptom score fell by 5.49 points over twelve weeks on 5 mg tadalafil and by 4.08 points on placebo. Erectile function improved by 5.24 versus 1.88 points. Tamsulosin ran in the trial as a comparator arm; a direct comparison with tadalafil is not reported in the abstract.

What are the side effects of tadalafil?

In a meta-analysis, serious side effects were no more frequent than on placebo, relative risk 1.00. Discontinuations because of side effects, however, were more frequent, odds ratio 1.79. Compared with sildenafil, muscle pain and back pain occur more often, facial flushing less often. The overall rate and efficacy of the two drugs are similar.

What must tadalafil not be combined with?

Concomitant use with nitrates and with guanylate cyclase stimulators is contraindicated according to the European marketing authorization. This is not a precaution but a contraindication. An independent blood-pressure-lowering therapeutic benefit of the drug, by contrast, is not verified and cannot be derived from its vascular effect. Assessment belongs in the hands of a physician.

Is tadalafil approved in Germany?

Yes. Cialis has been approved in the EU for erectile dysfunction since November 12, 2002, and additionally for symptoms of benign prostatic enlargement since 2012. The drug is prescription-only. For use as a general vascular drug or in the area of cognition, by contrast, there are no approval data and no approval trials.

The podcast episode (in German)

Episode 21

Tadalafil: a sex pill for the brain? Prostate, blood pressure & head fact-checked

The podcast by Paul Höser (Episode 21) · with Paul & Paula. A fresh, positive AI dialogue episode about the underrated vascular tool tadalafil: how the long-acting PDE5 inhibitor (up to 36 hours) prolongs the body’s own relaxation signal in the blood vessels, why low-dose daily use is officially approved for prostate symptoms (Yokoyama 2015), what the scene reports about endothelial and pump effects – and what brain research says (PASTIS 2022 sobering, ETLAS-2 in Stroke 2025 missed its primary goal, with many side effects and only a non-significant trend in white matter changes). Plus the one hard rule: never combine with nitrates. Information only, no dosing or usage recommendation – prescription-only.

Listen on Spotify

Related

Sources

Open in the database – with search, filters and comparison (German app)

Information only, not medical advice and no usage or dosing recommendation. Prescription-only and unapproved substances belong in medical hands. Last updated: 2026-10-04.