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Viagra
From: £18.99
Sildenafil is the UK’s most widely used ED treatment and the active ingredient in Viagra. It works within 30–60 minutes and remains effective for 4–6 hours. Available in 25mg, 50mg and 100mg. Clinically equivalent to branded Viagra at a significantly lower cost.
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Additional information
| Quantity | 16, 32, 4, 8 |
|---|---|
| Strength | 100mg, 25mg, 50mg |
Overview
Content Written by:
Hanifa Tai
Hanifa Tai
Role: Pharmacist & Content Writer
GPhC Number: 2074961
Content Published: 01/04/2026
Next Review: 01/04/2027
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Description
What Is Sildenafil?
Sildenafil is a prescription medicine used to treat erectile dysfunction (ED) in adult men. It belongs to the phosphodiesterase type 5 (PDE5) inhibitor class. It works by improving blood flow to the penis during sexual stimulation. The branded version of Sildenafil is Viagra, originally developed by Pfizer. Generic Sildenafil contains exactly the same active ingredient and works in the same way.
How Does It Work?
During sexual arousal, the body releases nitric oxide which triggers production of cyclic GMP, relaxing smooth muscle in penile blood vessels. An enzyme called PDE5 breaks down cyclic GMP. Sildenafil temporarily blocks this enzyme, allowing blood flow to improve and supporting erection quality. Sexual stimulation is still required — it does not cause an automatic erection.
Dosing & How to Take
Available in 25mg, 50mg and 100mg. Most men start at 50mg. Take 30–60 minutes before sexual activity. Swallow whole with water. Can be taken with or without food, though high-fat meals may delay onset. Maximum one tablet per 24-hour period.
How Effective Is It?
Clinical studies show Sildenafil improves erections in the majority of men with ED. It is often the first-line recommended treatment in UK clinical practice. Trying the medication on at least four separate occasions is recommended before deciding whether it is effective.
Sildenafil vs Viagra
Sildenafil and Viagra contain the same active ingredient in the same strengths. The only difference is branding and packaging. In terms of safety, effectiveness and regulatory approval, they are clinically identical. Generic Sildenafil is typically more affordable.
FAQ
Q: How quickly does Sildenafil work?
A: Sildenafil typically begins working within 30 to 60 minutes. Taking it on a lighter stomach may allow faster onset.
Q: How long does Sildenafil last?
A: The effects usually last around 4 to 6 hours, though this varies slightly between individuals.
Q: Can I take Sildenafil with alcohol?
A: Moderate alcohol consumption is unlikely to significantly reduce effectiveness. However, excessive alcohol can impair erection quality and increase dizziness risk. Limit alcohol for best results.
Q: Is Sildenafil addictive?
A: No. Sildenafil is not addictive and does not cause physical dependency. It has been safely used by millions of men for over two decades.
Q: What if Sildenafil doesn’t work?
A: Common reasons include taking it after a heavy meal, insufficient stimulation, high anxiety, excess alcohol, or incorrect dose. If multiple attempts are unsuccessful, your pharmacist may adjust the dose or recommend an alternative such as Tadalafil.
Side Effects
Common Side Effects
These are usually mild and resolve as the medicine leaves the body:
- Headache
- Facial flushing
- Nasal congestion
- Indigestion
- Dizziness
- Visual disturbances (e.g. blue tinge to vision)
Rare but Serious Side Effects — Seek Urgent Medical Attention
- Chest pain — seek urgent medical help
- Sudden loss of vision — seek urgent medical help
- Sudden hearing loss — seek urgent medical help
- Erection lasting longer than 4 hours (priapism) — seek urgent medical help
Do Not Take If You:
- Use nitrate medication or ‘poppers’
- Have been advised to avoid sexual activity due to heart disease
- Have severe low blood pressure
- Have recently had a heart attack or stroke
- Have certain rare hereditary eye conditions
Cardiovascular Note: Sexual activity places moderate physical strain on the cardiovascular system. If you can climb two flights of stairs without chest pain or severe breathlessness, sexual activity is generally considered safe. Men with unstable heart disease should be assessed before treatment.
