Tadalafil inhibits phosphodiesterase type 5, preserving nitric-oxide-mediated cGMP signalling in smooth muscle. This supports erections with sexual stimulation and improves lower urinary tract symptoms in benign prostatic hyperplasia; surrogate endothelial effects do not establish cardiovascular prevention or longevity.
What it is, why people use it, the evidence, and what to know before trying it.
Regulatory status: Prescription-only in the United States, European Union, UK, Canada, and Australia. Not a controlled substance in the US. EMA-authorized Cialis and Adcirca plus generics. Absolute contraindications on current US labeling: any organic nitrate (regular or intermittent); serious hypersensitivity to tadalafil; guanylate-cyclase stimulators (riociguat).
Mechanism evidence: human
Tadalafil is a **prescription PDE5 inhibitor** with **strong** evidence for three labeled jobs that must be kept apart: **as-needed 10–20 mg for ED**, **once-daily 2.5–5 mg for ED**, and **once-daily 5 mg for BPH/LUTS symptoms** (and the dual ED+BPH claim at 5 mg daily). Those are different protocols; the 5 mg daily wellness story is not a license to treat PRN and daily as one intervention, and this file does not recommend either. What the evidence does **not** support is the marketing leap from those approvals to **endothelial rejuvenation, anti-inflammation, or fewer heart attacks**. Chronic **20 mg alternate-day** tadalafil can move FMD and some adhesion/ET-1/CRP numbers in tiny RCTs (**moderate** surrogate signal, **weak** at the actual **5 mg daily** amount; Rubio-Aurioles 2012 is a daily-5 mg **null** on PAT and biomarkers). Observational papers (Andersson, Kloner 2024) associate PDE5i exposure with lower MACE and death; they are **not** outcome RCTs, and the authors say so. Athlete RCTs are **null** on VO2max. BPH benefit is **symptoms**, not Qmax or surgery prevention.
Confidence: strong
Contraindications, interactions and clinical cautions from reviewed sources.
Tadalafil must not be combined with nitrates or riociguat because of dangerous hypotension. Headache, flushing, dyspepsia, nasal congestion, back pain and dizziness are common; sudden vision or hearing loss and priapism require urgent care. Cardiovascular fitness for sexual activity, alpha-blockers, kidney or liver disease and CYP3A interactions require prescriber review.
Public protocols that include Tadalafil (prescription PDE5 inhibitor) — evidence review. Open one to see the full context and source.
Dose and schedule patterns reported in public protocols; these are observations, not prescribing advice. Private and hidden usage is excluded.
Continue into interventions that appear alongside this one.