Sildenafil — Drug Interactions, Alcohol & Pregnancy Guide
Last reviewed: · Source: US FDA drug label database · 247CanITakeWith Editorial Team
- Sildenafil is a PDE5 inhibitor used for Erectile dysfunction.
- Alcohol: One or two drinks with sildenafil is usually fine, but heavy drinking causes a dangerous blood pressure drop and also reduces erectile function — defeating the point.
- Pregnancy: Sildenafil is not used for erectile dysfunction in pregnancy (not applicable), but Revatio (sildenafil for pulmonary arterial hypertension) carries specific risks near delivery that require specialist management.
- This page covers 1 specific drug combination with Sildenafil.
About Sildenafil
Sildenafil (Viagra) is available over-the-counter in the UK (Viagra Connect, 50mg). It should NOT be taken with nitrates (GTN spray, isosorbide mononitrate) — this causes a dangerous drop in blood pressure. Also avoid with alcohol.
Also sold as: Viagra, Revatio
Sildenafil at a glance
Sildenafil is classed as pde5 inhibitor and is used for erectile dysfunction, pulmonary arterial hypertension. It can be bought over the counter in the UK, but that does not mean it is safe with everything — check the label and ask a pharmacist if you take other medicines.
Typical adult dosing guidance: 25-100mg one hour before sexual activity. Your own label or prescription always takes priority over general figures.
Interactions most often flagged
- Nitrates (contraindicated)
- Alcohol
- Alpha-blockers
- Pregnancy (not applicable)
Before you combine Sildenafil with anything new
- Read the patient information leaflet for both products.
- Keep one up-to-date list of every medicine and supplement you take.
- Ask a pharmacist — it is free and takes a couple of minutes.
- Seek urgent medical help if you feel seriously unwell after combining medicines.
Sildenafil and Alcohol
One or two drinks with sildenafil is usually fine, but heavy drinking causes a dangerous blood pressure drop and also reduces erectile function — defeating the point.
Full guide →Sildenafil in Pregnancy
Sildenafil is not used for erectile dysfunction in pregnancy (not applicable), but Revatio (sildenafil for pulmonary arterial hypertension) carries specific risks near delivery that require specialist management.
Full guide →Sildenafil — Drug Combinations
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Frequently Asked Questions
What is Sildenafil used for?
Sildenafil is a PDE5 inhibitor used for Erectile dysfunction, Pulmonary arterial hypertension.
What is the maximum adult dose of Sildenafil?
The maximum adult dose is 25-100mg one hour before sexual activity. This is general guidance — always follow the dose on your prescription or product label, and check with a pharmacist if you're unsure.
Can I drink alcohol with Sildenafil?
One or two drinks with sildenafil is usually fine, but heavy drinking causes a dangerous blood pressure drop and also reduces erectile function — defeating the point.
Is Sildenafil safe to take during pregnancy?
Sildenafil is not used for erectile dysfunction in pregnancy (not applicable), but Revatio (sildenafil for pulmonary arterial hypertension) carries specific risks near delivery that require specialist management.
Is Sildenafil available over the counter in the UK?
Yes, Sildenafil is available over the counter in the UK.
What should I check before taking Sildenafil with other medicines?
The interactions most often flagged for Sildenafil are: nitrates (contraindicated), alcohol, alpha-blockers, pregnancy (not applicable). Tell your pharmacist or prescriber about everything you take, including over-the-counter products, supplements and herbal remedies, before combining it with anything new.
What are the brand names for Sildenafil?
Sildenafil is sold under brand names including Viagra, Revatio. The active ingredient is the same, so check labels carefully to avoid doubling up on it.
Do I need a prescription for Sildenafil?
Sildenafil does not need a prescription in the UK, but a pharmacist can still advise whether it suits you alongside your other medicines.
Not sure if Sildenafil is safe with your other medications?
HealthLabs.com lets you check liver enzyme or kidney function levels before combining medications long-term — no GP referral needed.
Check your levels at HealthLabs →Always speak to your pharmacist or GP for personalised medical advice. Affiliate link — we may earn a commission.