Viagra and Sildenafil: Prescription and Safety Questions

General information for adults aged 18 and over. This article does not provide an individual diagnosis or treatment plan.

Does sildenafil require a prescription?

Check with a licensed pharmacist in your country. In the UK, the NHS explains that sildenafil is mostly supplied on prescription, with some pharmacy access after a pharmacist assessment. This UK guidance should not be treated as a worldwide rule. See NHS sildenafil information.

What should I discuss with a professional?

Explain any erection problems, existing health conditions and all medicines or supplements you take. Sildenafil can interact with medicines, particularly nitrates used for chest pain. A clinician or pharmacist should assess suitability; do not choose a dose from a store article. Read the medicine leaflet and follow professional instructions.

When is prompt care needed?

An erection lasting longer than four hours requires immediate medical attention. This refers to a prolonged erection, not simply the time since taking a medicine. The NIDDK also advises prompt care for vision or hearing loss after oral ED medicines. See NIDDK treatment and safety guidance.

Where should I start?

Ask a qualified healthcare professional about assessment and treatment options. The NIDDK advises discussing ED medicines with a professional before ordering online. Product descriptions for adult accessories should not be used to select medical treatment.

Editorially updated: October 6, 2026.