BNF Sildenafil: Complete Treatment Guide

Sildenafil is a proven erectile dysfunction treatment listed in the British National Formulary (BNF). As a PDE5 inhibitor, it helps improve blood flow when sexually stimulated. EverydayMeds offers both generic sildenafil and branded Viagra, allowing patients to choose their preferred option following a clinical consultation with our UK-licensed prescribers.

  • Available in 25mg, 50mg, and 100mg strengths as per BNF guidelines
  • Works within 30-60 minutes with effects lasting 4-6 hours
  • Requires prescription following comprehensive medical assessment
  • Choice between generic sildenafil or branded Viagra at checkout
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Not sure which one? Here's the honest comparison.

Sildenafil
~60 min
~4 hrs
you like to plan ahead
Tadalafil (as-needed)Most prescribed
~30 min
up to 36 hrs
you want a whole weekend covered
Tadalafil Daily
always active
continuous
you never want to think about timing
Vardenafil
~15–30 min
~8 hrs
you want the fastest onset

How ED treatment works in your body.

Increases blood flow

Increases blood flow

When PDE5 is suppressed, blood is able to flow more freely through the body—including to the (you guessed it) penis.

Increase erections

Increase erections

More blood flow to the penis means harder, more satisfying erections once you're sexually stimulated.

Understanding BNF Sildenafil Treatment Options

What is BNF Sildenafil?

The British National Formulary (BNF) lists sildenafil as a phosphodiesterase type 5 (PDE5) inhibitor for treating erectile dysfunction. Originally developed by Pfizer as Viagra, sildenafil is now available as both the branded medication and generic alternatives. Both contain identical active ingredients and work in the same way, with generic versions typically offered at lower costs.

How Sildenafil Works

Sildenafil blocks the PDE5 enzyme, which normally breaks down cyclic GMP - a chemical that helps relax blood vessels in the penis. By inhibiting this enzyme, sildenafil allows increased blood flow during sexual arousal. It's important to understand that sildenafil doesn't cause automatic erections; sexual stimulation is still required for the medication to be effective.

BNF Dosage Guidelines

According to BNF recommendations, sildenafil is available in three strengths: 25mg, 50mg, and 100mg. The typical starting dose is 50mg, taken approximately one hour before sexual activity. Based on effectiveness and tolerability, the dose may be adjusted to 25mg (if side effects occur) or increased to 100mg (if 50mg proves insufficient). Only one dose should be taken within any 24-hour period.

Clinical Assessment Requirements

Before prescribing sildenafil, healthcare professionals conduct comprehensive assessments covering cardiovascular health, current medications, and medical history. This evaluation is crucial because sildenafil can interact with certain medications, particularly nitrates used for angina, which can cause dangerous drops in blood pressure. Patients with recent heart attacks, strokes, or severe liver problems may not be suitable candidates.

Effectiveness and Expectations

Clinical studies show sildenafil is effective for approximately 70-80% of men with erectile dysfunction. The medication typically begins working within 30-60 minutes, with peak effects occurring around 1-2 hours after taking. Effects can last up to 6 hours, though this doesn't mean erections last this long - they should return to normal after sexual activity ends. Fatty meals may delay the onset of action.

Safety Considerations

The BNF emphasises several important safety considerations. Sildenafil is contraindicated with nitrate medications due to potentially fatal blood pressure drops. Common side effects include headaches, facial flushing, and nasal congestion, which are usually mild and temporary. Patients should seek immediate medical attention if experiencing erections lasting over 4 hours or sudden vision/hearing changes.

Choosing Between Branded and Generic

At EverydayMeds, patients can choose between branded Viagra and generic sildenafil during checkout. Both options contain the same active ingredient and undergo identical regulatory approval processes. The choice often comes down to personal preference and cost considerations, with both options requiring the same prescription process through our qualified healthcare professionals.

What you need to know about erectile dysfunction

It's one of the most common conditions we treat, and one of the most treatable.

What is Erectile Dysfunction?
ED means finding it hard to get or keep an erection firm enough for sex. It's not unusual to have an off night; the point at which it's worth doing something is when it's happening regularly, or when it's starting to bother you.
How will I feel when I take ED medication?
For most men, nothing feels different day to day. The medication works in the background — when you're sexually aroused, it helps blood flow where it's needed, so erections come more easily and last longer. It doesn't cause arousal on its own. Some men notice mild, short-lived effects like a headache, facial flushing or a stuffy nose, which usually pass as the dose wears off.
Why do I need a prescription for ED medication?
ED treatments are prescription-only medicines in the UK because they aren't suitable for everyone — for example, alongside certain heart conditions or medications like nitrates. That's why we ask you to complete a short online consultation first. A UK-registered prescriber reviews your answers to make sure your chosen treatment is safe and right for you before it's dispensed.
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