Sildenafil Citrate: Quick Facts & Information

Sildenafil citrate is the active ingredient in erectile dysfunction treatments, available as both generic sildenafil and branded Viagra. This prescription-only medicine works by increasing blood flow to help men achieve and maintain erections when sexually aroused. EverydayMeds offers both branded and generic options following an online consultation with UK-licensed prescribers.

  • Available in 25mg, 50mg, and 100mg tablets with typical starting dose of 50mg
  • Works within 30-60 minutes and effects may last 4-6 hours
  • Requires sexual arousal to be effective - does not cause automatic erections
  • Choice between branded Viagra or generic sildenafil 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
Explore now
Tadalafil (as-needed)Most prescribed
~30 min
up to 36 hrs
you want a whole weekend covered
Explore now
Tadalafil Daily
always active
continuous
you never want to think about timing
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Vardenafil
~15–30 min
~8 hrs
you want the fastest onset
Explore now

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.

How Sildenafil Citrate Works and Dosage Guidelines

Mechanism of Action

Sildenafil citrate functions as a PDE5 inhibitor, blocking the phosphodiesterase type 5 enzyme to increase blood flow to the penis during sexual arousal. This medication does not cause automatic erections and requires sexual stimulation to be effective. The enhanced blood flow helps men with erectile dysfunction achieve and maintain suitable erections for sexual activity.

Dosage and Administration

Sildenafil citrate is available in three strengths: 25mg, 50mg, and 100mg tablets. Healthcare providers typically prescribe a starting dose of 50mg, which may be adjusted to 25mg or 100mg based on individual response and tolerability. The medication should be taken 30-60 minutes before anticipated sexual activity, with a maximum of one dose per 24-hour period.

Onset and Duration

Most men experience effects within 30-60 minutes of taking sildenafil citrate, though this may vary based on individual factors and food intake. Fatty meals can delay the onset of action. The medication's effects may last 4-6 hours, though this refers to the window when the medication may be effective, not the duration of any single erection.

Branded vs Generic Options

EverydayMeds offers both Viagra (the original branded version) and generic sildenafil citrate. Both contain the same active ingredient in identical doses and work in the same way. Patients can choose between branded or generic options at checkout based on personal preference, with generic versions typically offered at lower cost whilst maintaining equivalent effectiveness.

Safety Considerations

Sildenafil citrate requires a prescription following consultation with a UK-licensed healthcare professional. The medication is not suitable for everyone, particularly those taking nitrate medications, those with severe heart conditions, or recent stroke or heart attack history. A comprehensive medical assessment evaluates cardiovascular health, current medications, and medical history before prescribing.

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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