Viagra FAQ: Common Questions & NHS Guidelines

Find quick answers to frequently asked questions about Viagra, the branded erectile dysfunction treatment from Pfizer. This comprehensive FAQ covers everything from how Viagra works to NHS guidelines, dosages, side effects, and safety considerations. Whether you're considering Viagra for the first time or need specific information about this prescription medication, our expert-reviewed answers provide the essential facts you need. EverydayMeds offers both branded Viagra and generic Sildenafil following consultation with our UK-registered prescribers.

  • How Viagra works and when it becomes effective
  • Available dosages and NHS prescribing guidelines
  • Common side effects and important safety warnings
  • Eligibility criteria and consultation requirements
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.

Most Asked Questions About Viagra Treatment

What is Viagra and How Does It Work?

Viagra is the branded version of sildenafil citrate, manufactured by Pfizer. It works as a PDE5 inhibitor, blocking the phosphodiesterase type 5 enzyme to increase blood flow to the penis during sexual arousal. Viagra doesn't cause automatic erections - sexual stimulation is still required. The medication typically begins working within 30-60 minutes and effects can last 4-6 hours, though this doesn't mean the erection lasts this long.

EverydayMeds provides both branded Viagra and generic Sildenafil, giving patients choice between the original branded medication and the more cost-effective generic alternative. Both contain the same active ingredient and offer identical effectiveness.

What Dosages Are Available?

Viagra comes in three strengths: 25mg, 50mg, and 100mg tablets. The typical starting dose is 50mg, taken approximately one hour before sexual activity. Your prescriber may adjust this to 25mg if you experience side effects or increase to 100mg if 50mg proves insufficient. The maximum dose is one tablet per 24-hour period, regardless of strength.

High-fat meals can delay how quickly Viagra works, so taking it on an empty or light stomach may provide faster results. The medication should be taken with water and never crushed or split.

Who Can Take Viagra?

Viagra is suitable for adult men aged 18 and over who experience erectile dysfunction. However, it's not appropriate for everyone. You'll need to complete a clinical assessment with a UK-registered prescriber who will evaluate your cardiovascular health, current medications, and medical history.

Men taking nitrate medications (such as GTN spray for heart conditions) cannot take Viagra due to dangerous interactions that can cause severe blood pressure drops. Those with severe heart disease, recent heart attacks or strokes, severe liver problems, or very low blood pressure may also be advised against using Viagra.

What Are the Common Side Effects?

The most common side effect is headache, experienced by more than 1 in 10 users. Other frequent side effects include facial flushing, indigestion, nasal congestion, dizziness, visual disturbances (such as a blue tinge to vision), and nausea. These effects are usually mild and temporary, often reducing as your body adjusts to the medication.

Serious side effects requiring immediate medical attention include priapism (painful erection lasting more than 4 hours), sudden vision or hearing loss, chest pain during sexual activity, or signs of allergic reaction. If you experience any of these, seek emergency medical help immediately.

How Does Viagra Compare to Generic Sildenafil?

Viagra and generic Sildenafil contain identical active ingredients and work in exactly the same way. The main differences are price and branding - Viagra typically costs more as the original branded product, whilst Sildenafil offers the same therapeutic benefits at a lower cost. Both are regulated to the same strict UK quality standards.

Some patients prefer the branded Viagra for reassurance, whilst others choose generic Sildenafil for better value. At EverydayMeds, patients can select their preference during the checkout process after completing their clinical consultation.

Important Drug Interactions

Never combine Viagra with nitrate medications or recreational drugs containing nitrates (such as "poppers"). This combination can cause life-threatening blood pressure drops. Alpha-blockers used for prostate problems may also interact, potentially causing dizziness or fainting.

Inform your prescriber about all medications you're taking, including over-the-counter products and supplements. Some HIV medications, antifungals, and certain antibiotics can affect how your body processes Viagra, potentially requiring dose adjustments.

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