Essential Sildenafil Quick Facts & Reference Guide

Sildenafil is a proven PDE5 inhibitor prescribed for erectile dysfunction, offering the same active ingredient as Viagra at a lower cost. This quick reference guide provides essential facts about dosages, timing, interactions, and safety information that men need to know. Understanding these key details helps ensure safe and effective use of this prescription medication. EverydayMeds offers both generic sildenafil and branded Viagra options, allowing patients to choose their preferred treatment during checkout following a clinical consultation with our UK-registered prescribers.

  • Available in 25mg, 50mg, and 100mg tablets with 50mg as the standard starting dose
  • Takes 30-60 minutes to work and effects last up to 4-6 hours
  • Cannot be taken with nitrates or within 24 hours of another dose
  • Requires prescription following clinical assessment by UK-licensed prescriber
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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 Sildenafil Quick Reference Information

Dosage and Administration Quick Facts

Sildenafil is available in three strengths: 25mg, 50mg, and 100mg tablets. The standard starting dose is 50mg, taken approximately 30-60 minutes before anticipated sexual activity. Based on effectiveness and tolerability, your prescriber may adjust the dose to 25mg if side effects occur, or increase to 100mg if the response is insufficient. The maximum dosing frequency is once per 24-hour period, regardless of strength.

For optimal effectiveness, sildenafil can be taken with or without food. However, high-fat meals may delay the onset of action, so taking on an empty stomach or after a light meal typically provides faster results. The medication requires sexual stimulation to work effectively and does not cause automatic erections.

Timing and Duration Facts

Sildenafil typically begins working within 30-60 minutes of administration, though this can vary between individuals. The effects can last up to 4-6 hours, providing a window during which achieving an erection may be easier when sexually aroused. It's important to understand that this duration refers to the medication's presence in your system, not the length of any erection.

Some men may find the medication works faster on subsequent uses as their body becomes accustomed to it. The timing can be affected by factors including age, overall health, other medications, alcohol consumption, and food intake.

Critical Drug Interaction Information

The most dangerous interaction occurs with nitrate medications, including GTN spray, isosorbide mononitrate, and recreational substances containing nitrates ("poppers"). This combination can cause a severe, potentially life-threatening drop in blood pressure. Always inform your prescriber about all medications you're taking, including over-the-counter remedies and supplements.

Alpha-blockers used for prostate conditions or blood pressure may also interact with sildenafil, potentially causing dizziness or fainting. If you're prescribed both types of medication, your prescriber will provide specific guidance about timing and monitoring. Grapefruit juice should be avoided as it can increase sildenafil levels in your blood.

Common Side Effects Quick Reference

The most frequently reported side effect is headache, experienced by more than 1 in 10 men. Other common effects include facial flushing, indigestion, nasal congestion, dizziness, and temporary visual changes such as increased sensitivity to light or a blue colour tinge to vision. These effects are generally mild and temporary, often diminishing with continued use.

Most side effects resolve within a few hours as the medication clears from your system. Staying hydrated and avoiding alcohol can help minimise some effects. If side effects are persistent or particularly bothersome, your prescriber may recommend adjusting the dose.

When to Seek Immediate Medical Help

Certain rare but serious side effects require emergency medical attention. Priapism, an erection lasting more than four hours, is a medical emergency that can cause permanent damage if not treated promptly. Sudden vision or hearing loss, chest pain during sexual activity, or signs of severe allergic reaction (difficulty breathing, swelling, severe rash) also require immediate medical care.

Any chest pain or discomfort during sexual activity should be taken seriously, as it may indicate underlying cardiovascular issues. Stop activity immediately and seek medical help if this occurs.

Prescription and Availability Facts

Sildenafil is a prescription-only medicine requiring consultation with a UK-registered prescriber. At EverydayMeds, our clinical assessment evaluates your suitability for treatment, considering your medical history, current medications, and overall cardiovascular health. This ensures safe prescribing and identifies any potential contraindications.

Patients can choose between generic sildenafil and branded Viagra during checkout, as both contain the same active ingredient but differ in cost. The generic version offers identical effectiveness and safety profile while providing significant cost savings for many patients.

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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