Safety information · Internal patient-safety page
Tadalafil safety summary
Tadalafil treats erectile dysfunction by relaxing blood vessels in the penis so blood flow can support an erection during sexual stimulation. Its long half-life makes it the “weekend” PDE5 inhibitor: a single dose can give a window of effectiveness of up to 36 hours.
What it's used for
- On-demand: 10 mg taken at least 30 minutes before sexual activity. Adjustable to 20 mg or 5 mg by the doctor.
- Daily low-dose: 2.5 mg or 5 mg once a day for men with frequent activity or co-existing benign prostatic hyperplasia (BPH).
- Effect window of up to 36 hours from a single dose; food and alcohol have minimal impact compared with sildenafil.
Most common side effects
- Headache.
- Facial flushing.
- Indigestion, reflux or stomach discomfort.
- Back pain or muscle aches, characteristic of tadalafil, usually 12–24h after dosing.
- Nasal congestion.
Serious side effects: stop and seek care
- Erection lasting more than 4 hours (priapism): A&E.
- Sudden vision loss in one or both eyes (NAION): stop and seek care.
- Sudden hearing loss or tinnitus.
- Chest pain during or shortly after sex: call emergency services.
- Severe allergic reaction.
Who should not take it
- Any nitrate medicine or amyl-nitrite recreational drug (“poppers”): life-threatening blood-pressure drops.
- Riociguat or any guanylate-cyclase stimulator.
- Recent heart attack, stroke or unstable angina in the last 6 months.
- Severe liver impairment, severe low or uncontrolled high blood pressure.
- Hereditary degenerative retinal disorders or prior NAION.
Interactions to flag
- Alpha-blockers: discuss with the doctor; co-administration may need a lower starting dose.
- Strong CYP3A4 inhibitors (ritonavir, ketoconazole, clarithromycin): dose adjustment needed.
- Other PDE5 inhibitors (sildenafil, vardenafil, avanafil): never combine.
- Alcohol in large amounts can amplify dizziness and lower blood pressure further.
- Grapefruit juice can raise plasma levels.
Message us in the app chat if you notice any of these
- Back or muscle pain that doesn't resolve within 48h or stops you from sleeping.
- A persistent erection, vision or hearing change: A&E first, then message us.
- Heart symptoms during sex (chest pressure, breathlessness, palpitations).
AEMPS CIMA: Tadalafil
Back to your consultationThis page summarises information from the regulator-approved leaflet for reference only. It is not medical advice and does not replace the assessment of an EU-licensed doctor. Your doctor will review your individual history, dose and interactions during your consultation.