Sildenafil: what it is and who it is for.
Sildenafil is a prescription-only medicine used in erectile dysfunction. This page explains how it works, who it may be suitable for, who it is not suitable for, and what our online assessment involves.
Generic medicine
Sildenafil is the active ingredient in Viagra®. The generic contains the same active ingredient and is usually less expensive.
Simple, Private, Straightforward
Getting treatment should never be complicated or embarrassing. Our streamlined process gets you the care you need quickly and confidentially.
01. Online Consultation
Complete a short, confidential health questionnaire covering your medical history, current medications, and cardiovascular health. This takes under 10 minutes.
02. Prescriber Review
A UK-registered prescriber reviews your assessment to decide whether sildenafil is safe for you, including checking for any contraindications such as nitrate medications.
03. Discreet Delivery
If it is prescribed, your medication is dispensed from our GPhC pharmacy and shipped in completely plain, unbranded packaging - no logos, no pharmacy markings, total discretion.
How sildenafil works
Sildenafil works by inhibiting PDE5, an enzyme that restricts blood flow to the penis. By blocking PDE5, sildenafil allows smooth muscle relaxation and increased blood flow during sexual stimulation, producing and maintaining an erection.
- Widely studiedOne of the most extensively studied medicines for erectile dysfunction. It does not work for everyone.
- Fast-ActingWorks within 30-60 minutes of taking the tablet, with effects lasting up to 4-6 hours.
- Flexible DosingAvailable in 25mg, 50mg, and 100mg strengths - your prescriber will recommend the right starting dose for you.
Safety & Information
Total Confidentiality
We understand discretion is paramount. Your consultation is encrypted in transit and at rest, your health information stays with our own clinical and pharmacy team, and your medication arrives in completely plain packaging with zero pharmacy branding. We never sell your data or share it for marketing.
How do I take Sildenafil?
Take one tablet 30-60 minutes before sexual activity. The standard starting dose is 50mg. Do not take more than one dose in 24 hours. Do not take with alcohol or grapefruit juice as these may affect effectiveness.
Side Effects
Common side effects include headache, facial flushing, and mild nasal congestion. Sildenafil must not be taken with nitrate medications - your prescriber will screen for this during consultation.
Message our clinical team from your account
Confident, discreet care - starting today.
Take the first step in a few minutes. A UK-registered prescriber reviews your answers and decides whether treatment is suitable for you.
Clinically reviewed by Dr Wisam Tatari, Clinical Lead, Independent Prescriber, GPhC 2063769.
Last reviewed 8 September 2026. We review this page when the clinical guidance it describes changes, and at least once a year.