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PDE5 Inhibitor

Tadalafil (BPH)

Brand names: Cialis, Adcirca

Tadalafil is a long-acting phosphodiesterase-5 inhibitor used for benign prostatic hyperplasia and erectile dysfunction, and at specialist level for pulmonary arterial hypertension.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

Do not split tadalafil tablets; entire dose should be taken. Tadalafil tablets for use as needed: ED: Starting dose: 10 mg as needed prior to sexual activity. Increase to 20 mg or decrease to 5 mg based upon efficacy/tolerability. Improves erectile function compared to placebo up to 36 hours post dose. Not to be taken more than once per day ( 2.1 ). Tadalafil tablets for once daily use: ED: 2.5 mg taken once daily, without regard to timing of sexual activity. May increase to 5 mg based upon efficacy and tolerability ( 2.2 ). BPH: 5 mg, taken at approximately the same time every day ( 2.3 ) ED and BPH: 5 mg, taken at approximately the same time every day ( 2.3 , 2.4 ) Tadalafil tablets may …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2024-10-16. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It inhibits phosphodiesterase type 5, preventing the breakdown of cyclic GMP and prolonging smooth muscle relaxation and vasodilatation in the corpus cavernosum and lower urinary tract; its long duration of action distinguishes it from shorter-acting agents in the class.

Prescribing in practice

  • It is contraindicated with nitrates and with nicorandil because the combination can cause severe, potentially life-threatening hypotension.
  • Use with caution alongside alpha-blockers and other antihypertensives, and in men with significant cardiovascular disease or recent stroke or myocardial infarction; consult the SPC.
  • Prolonged or painful erection (priapism) can occur and requires urgent medical attention.

Monitoring

Confirm the patient is not taking nitrates or nicorandil and assess cardiovascular fitness before use. Review blood pressure and symptoms where alpha-blockers or other antihypertensives are co-prescribed, and reassess response and tolerability.

Counselling the patient

  • Never take this medicine with nitrate heart medicines (such as GTN sprays or tablets) or with nicorandil, as your blood pressure could drop dangerously.
  • Seek urgent medical help if you have an erection lasting more than four hours.
  • Tell your prescriber about any heart problems, and stop and seek advice if you develop chest pain, sudden vision changes or fainting.

Evidence & guidelines

A phosphodiesterase-5 inhibitor recommended in UK guidance (NICE) for benign prostatic hyperplasia and erectile dysfunction, with the nitrate contraindication a long-standing class safety point.

Reference: NICE NG97; SPC tadalafil; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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