Complete Sildenafil BNF Guide for ED Treatment

Sildenafil is a proven prescription treatment for erectile dysfunction, available in both generic and branded forms. This comprehensive guide covers BNF information, dosages, eligibility criteria, and safety considerations. EverydayMeds offers both sildenafil (generic) and Viagra (branded) options, allowing patients to choose the most suitable treatment following clinical assessment by UK-licensed prescribers.

  • Understanding sildenafil mechanism and BNF classification
  • Available dosages and how to determine the right strength
  • Eligibility criteria and contraindications for safe use
  • Important drug interactions and safety considerations
Start your free consultation

Takes less than 2 minutes to complete, 100% online

More pleasure. Less waiting. Built to last.

Get Started

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.

Sildenafil BNF Information and Clinical Overview

What is Sildenafil According to BNF Guidelines?

Sildenafil is classified in the BNF (British National Formulary) as a phosphodiesterase type-5 (PDE5) inhibitor used for treating erectile dysfunction. The medication works by increasing blood flow to the penis during sexual arousal, helping men achieve and maintain erections suitable for sexual activity. Sildenafil requires sexual stimulation to be effective and does not cause automatic erections.

Available Forms and Dosage Options

According to BNF guidance, sildenafil is available in 25mg, 50mg, and 100mg tablet strengths. The typical starting dose is 50mg, taken approximately one hour before sexual activity. Depending 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 a 24-hour period.

Branded vs Generic Options

EverydayMeds offers both sildenafil (generic) and Viagra (branded) formulations. Both contain the same active ingredient - sildenafil citrate - and work identically. The choice between generic and branded options often depends on patient preference and cost considerations. Both require the same clinical assessment and prescription process.

Eligibility and Assessment Requirements

BNF guidelines specify that sildenafil should only be prescribed to adult men following appropriate clinical assessment. This evaluation considers cardiovascular health, current medications, and medical history. Men with certain heart conditions, those taking nitrate medications, or with severe liver problems may not be suitable candidates for treatment.

Important Contraindications

The BNF lists several absolute contraindications for sildenafil use. These include concurrent use of nitrate medications (such as GTN spray), recent heart attack or stroke (within six months), severe heart disease, very low blood pressure, and severe liver impairment. Additionally, men taking riociguat for pulmonary hypertension should not use sildenafil.

Drug Interactions and Safety

Sildenafil can interact with various medications, particularly those affecting blood pressure. Alpha-blockers, some antifungal medications, and certain antibiotics may require dose adjustments or contraindicate sildenafil use entirely. The combination with nitrates is particularly dangerous and can cause life-threatening drops in blood pressure.

Common Side Effects

BNF documentation indicates that sildenafil may cause headaches, facial flushing, indigestion, nasal congestion, and dizziness. These effects are typically mild and temporary. More serious side effects, while rare, include prolonged erections lasting over four hours (priapism) and sudden vision or hearing changes, which require immediate medical attention.

Getting Sildenafil Through EverydayMeds

EverydayMeds provides convenient access to both sildenafil and Viagra following online consultation with UK-licensed prescribers. The assessment ensures treatment safety and appropriateness while maintaining confidentiality. Patients can choose between generic sildenafil or branded Viagra at checkout, with both options delivered discreetly to UK addresses.

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.
Couple laughing together

How it works

Achieve your goals in just a few simple steps.

Step 1

Start Free Consultation

Select safe UK treatments. Quick answers.

Step 2

Review By Our Clinical Team

Our expert team will use your consultation as the basis of our recommendation and communicate with you.

Step 3

Get it delivered fast

We’ll deliver direct to you, as quickly as tomorrow.

Frequently asked questions