A guide to Sildenafil – manual

What is Sildenafil?

Sildenafil, the active ingredient in Viagra, is a prescription medication used to treat erectile dysfunction. It works by increasing blood flow to the penis, helping men achieve and maintain an erection when sexually stimulated.

Key Benefits:

Clinically proven to improve erectile function
Works within 30–60 minutes
Lasts for up to 4–6 hours

For best results, take Sildenafil as prescribed and avoid heavy meals or excessive alcohol before use.

How does Sildenafil work?

Sildenafil is a PDE5 inhibitor that helps improve blood flow to the penis when you're aroused. It works by relaxing and expanding blood vessels, making it easier to achieve and maintain an erection.

Since Sildenafil and Viagra contain the same active ingredient (sildenafil citrate), they work in exactly the same way.

How effective is Sildenafil?

Studies suggest that 80% of men who take Sildenafil achieve erections firm enough for sex. In a comprehensive review of 82 clinical trials with over 47,000 patients, Sildenafil 50mg was identified as the most effective option compared to other ED medications—making it our preferred treatment at MANUAL.

How long does Sildenafil take to work, and what affects its timing?

Sildenafil typically starts working within 30 to 60 minutes, with peak effectiveness around the one-hour mark. However, it won’t cause an automatic erection—you’ll still need sexual stimulation for it to work.

Factors That Can Affect Sildenafil’s Timing

Food: Taking Sildenafil after a heavy meal may delay its effects. For faster results, consider taking it on an empty stomach.
Alcohol: Drinking excessive alcohol can reduce effectiveness and may make it harder to achieve an erection.

For the best experience, plan ahead and take Sildenafil in a way that supports its effectiveness. If you have any concerns, feel free to reach out—we’re happy to help.

How long do Sildenafil’s effects last, and how often can you take it?

Sildenafil’s effects typically last 4 to 5 hours, though this can vary between 2 to 6 hours depending on the individual.

How Often Can You Take Sildenafil?

Daily use is safe, but taking it more often won’t increase its effectiveness over time.
It’s best to take Sildenafil only when needed to achieve the best results.

If you’re unsure about the right frequency for you, feel free to reach out—we’re happy to help.

What are the ingredient in Sildenafil?

We believe it's important to know what's in your medication so you feel as confident as possible when taking it, please find below a list of active and inactive ingredients for Sildenafil (Viagra):

Active Ingredient:
Sildenafil

Inactive Ingredients:

(Tablet Core)
Microcrystalline cellulose
Calcium hydrogen phosphate (anhydrous)
Croscarmellose sodium
Magnesium stearate

(Film Coating)
Hypromellose
Titanium dioxide (E171)
Lactose monohydrate
Triacetin
Indigo carmine aluminum lake (E132)

It may seem like a long list of inactive ingredients, but rest assured these are necessary and contribute to the stability and effectiveness of Sildenafil. If you have specific sensitivities consult the patient information leaflet or one of our clinical team for more details.

What are the side effects of Sildenafil?

We hope you won’t experience any side effects, but we want you to feel informed and confident in spotting them if they do happen. Side effects from taking Sildenafil (Viagra) are usually mild and temporary.

Common side effects may include:
Headache, flushing, indigestion, nasal congestion, dizziness, nausea, hot flushes, and vision changes (such as a blue colour tinge or blurred vision).
These usually settle as the medication wears off. However, if side effects are severe or persistent you should stop taking the medication and seek medical advice.

Very rare but serious side effects such as chest pain, an allergic reaction (swelling of the face/lips or difficulty breathing), or an erection lasting more than 4 hours require immediate medical attention. If you experience severe side effects or have concerns, please seek medical assistance.

Call 111 for advice.
Visit your local Accident and Emergency (A&E) department.

Your health and well-being are our top priorities. We're here to support you every step of the way!