Viagra & Sildenafil Dosage Guide for UK Patients

Understanding the correct dosage for Viagra and sildenafil is crucial for safe and effective ED treatment. Both medications contain the same active ingredient (sildenafil citrate) but are available at different price points. This comprehensive guide explains dosages, how to take these medications safely, and what to expect from treatment. Always follow your prescriber's guidance and never exceed recommended doses.

  • Standard starting dose is typically 50mg, taken 30-60 minutes before sexual activity
  • Dosage can be adjusted to 25mg or 100mg based on effectiveness and side effects
  • Maximum of one dose per 24-hour period regardless of strength
  • Both branded Viagra and generic sildenafil are available in 25mg, 50mg, and 100mg strengths
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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.

Complete Dosage Information for Safe Treatment

Available Strengths and Starting Doses

Sildenafil is available in three main strengths: 25mg, 50mg, and 100mg tablets. Whether you choose branded Viagra or generic sildenafil, both contain identical active ingredients and follow the same dosing guidelines. Most patients begin treatment with a 50mg dose, which provides an effective balance between therapeutic benefit and potential side effects.

Your prescriber may recommend starting with 25mg if you're over 65, have certain medical conditions, or take medications that could interact with sildenafil. Conversely, the dose may be increased to 100mg if the 50mg strength proves insufficient, provided you tolerate the medication well.

How to Take Sildenafil Correctly

Take your prescribed dose approximately 30-60 minutes before planned sexual activity. The medication requires sexual stimulation to work effectively - it will not cause an automatic erection. Effects typically last 4-6 hours, though this doesn't mean an erection persists for this duration.

Avoid taking sildenafil with large or fatty meals, as this can delay the medication's onset of action. Alcohol should be limited, as excessive consumption can reduce effectiveness and increase the risk of side effects like dizziness or low blood pressure.

Dosage Adjustments and Considerations

Your healthcare provider may adjust your dosage based on several factors including age, overall health, other medications, and how well you respond to treatment. Patients with liver or kidney problems may require lower doses, whilst those taking certain medications might need dosage modifications.

Never take more than one dose in a 24-hour period, regardless of the strength prescribed. Taking multiple doses or exceeding recommended amounts significantly increases the risk of serious side effects, including dangerous drops in blood pressure.

Choosing Between Branded and Generic Options

EverydayMeds offers both Viagra (branded) and sildenafil (generic) options, allowing patients to choose based on their preferences and budget. Both medications are bioequivalent, meaning they work identically in your body. The generic version typically costs considerably less whilst providing the same therapeutic benefits.

Some patients prefer the branded option for peace of mind, whilst others opt for generic sildenafil for economic reasons. Your clinical assessment and prescription will specify sildenafil, and you can choose between branded or generic at checkout.

When to Contact Your Prescriber

Contact your healthcare provider if the prescribed dose seems ineffective after several attempts, or if you experience troublesome side effects. They may adjust your dosage or explore alternative treatments. Never adjust the dose yourself or share medication with others, as sildenafil requires individual medical assessment for safe use.

Seek immediate medical attention if you experience chest pain, dizziness, nausea during sexual activity, or an erection lasting more than four hours. These situations require urgent medical intervention.

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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