BNF Sildenafil Strength Comparison Guide

Understanding the different strengths of sildenafil available through the BNF can help you make an informed decision about ED treatment. Sildenafil is available in 25mg, 50mg, and 100mg tablets, with 50mg being the standard starting dose for most men. EverydayMeds offers both branded Viagra and generic sildenafil options, allowing you to choose based on your preferences and budget after completing our clinical assessment.

  • 25mg sildenafil - Lower starting dose for men with certain health conditions or those taking specific medications
  • 50mg sildenafil - Standard recommended starting dose for most men experiencing erectile dysfunction
  • 100mg sildenafil - Maximum dose that may be prescribed if 50mg proves insufficient
  • Generic sildenafil offers the same active ingredient as Viagra but at a more affordable price point
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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.

Sildenafil Dosage Options and Clinical Considerations

Understanding BNF Sildenafil Dosage Guidelines

The British National Formulary (BNF) provides clear guidance on sildenafil dosing for erectile dysfunction treatment. The standard starting dose is 50mg, taken approximately one hour before sexual activity. This dose can be adjusted based on individual response and tolerability, with options to reduce to 25mg or increase to 100mg as clinically appropriate.

25mg Sildenafil: When Lower Doses Are Recommended

The 25mg strength may be prescribed for men who are more sensitive to medications or those taking certain other medicines that could interact with sildenafil. This lower dose is also considered for men over 65 years of age or those with liver or kidney problems. While 25mg may be sufficient for some men, others may find they need a higher dose for optimal effectiveness.

50mg Sildenafil: The Standard Starting Point

Most men begin treatment with 50mg sildenafil, as recommended in BNF guidelines. This dose provides an effective balance between therapeutic benefit and minimising potential side effects. Clinical studies have shown that 50mg is effective for the majority of men with erectile dysfunction. At EverydayMeds, both generic sildenafil and branded Viagra are available in this strength, giving you choice at checkout.

100mg Sildenafil: Maximum Recommended Dose

The 100mg strength represents the maximum daily dose of sildenafil. This may be prescribed if 50mg has been well-tolerated but hasn't provided sufficient improvement in erectile function. However, increasing the dose also increases the likelihood of experiencing side effects such as headaches, flushing, or indigestion. Never exceed one tablet in 24 hours, regardless of strength.

Generic Sildenafil vs Branded Viagra

Generic sildenafil contains the same active ingredient as Viagra but is typically more cost-effective. Both options undergo the same rigorous quality standards and provide equivalent therapeutic effects. The choice between generic and branded options often comes down to personal preference and budget considerations. EverydayMeds stocks both options, ensuring you can select what works best for you.

Important Safety Considerations

Regardless of which strength you're prescribed, sildenafil should never be taken with nitrate medications used for chest pain, as this combination can cause a dangerous drop in blood pressure. Always inform your prescriber about all medications you're taking, including over-the-counter remedies and supplements. Side effects are generally mild but can include headaches, facial flushing, and nasal congestion.

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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