Effective ED support that can last up to 4 hours.
Used for
Treats erectile dysfunction by improving blood flow to the penis during sexual arousal.
How to use it*
Take 1 tablet 30 minutes before sexual activity.
How long to work
Starts working in 30–60 minutes, with effects lasting 4 to 6 hours.
Common side effects*
Headache, flushing, upset stomach, and nasal congestion.
Who should not take it*
Avoid if you have low blood pressure or uncontrolled high blood pressure.
Interactions*
May interact with nitrates and alpha-blockers. Avoid excessive alcohol and grapefruit.
Generic/branded
Generic: Sildenafil.
Brand: Viagra.
* Always consult the patient leaflet for comprehensive information.
Sildenafil and Viagra are the same medications, and are popular treatments for erectile dysfunction (ED) in men. Sildenafil (Viagra) was approved by the Food and Drug Administration (FDA) as the first phosphodiesterase-5 (PDE-5) inhibitor for treating ED.
Viagra has transformed the lives of millions of men by helping them achieve and maintain erections strong enough for sex.
The active ingredient in Viagra is Sildenafil citrate. Viagra is the popular brand name of Sildenafil manufactured by Pfizer. Sildenafil is sold generically under the same name.
A generic has the same qualities as the branded version and is used in the same way. The only differences may be the binding and inactive ingredients used, the product price, and the manufacturer. Generics are usually much more affordable than branded versions.
Sildenafil works by increasing blood flow to the penis. As with most ED treatments, Sildenafil (Viagra) belongs to a class of medication known as PDE-5 inhibitors.
Sexual arousal cause the nerves to send chemical messages to the blood vessels in your penis, leading to an erection.
Sildenafil inhibits PDE-5, which causes increased levels of a substance called cGMP in the spongy tissue of the penis.
This causes the smooth muscle in the wall of the penis to relax, allowing blood to flow into the chambers of the penis.
The bloodflow creates pressure, which makes the penis expand and compress the veins that normally allow blood to drain. Once the blood is trapped, the end result is an erection.
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Take 1 tablet when needed
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Take it with water
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Get in the mood
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Take your time
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Maximum dose
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Always follow your doctor's instructions and the details provided in your medication's instructions.
Viagra can last for up to four hours however, this doesn't mean you'll be erect throughout this time period.
After you climax, your penis will return to its flaccid state until you can achieve arousal again. If this medication does not have any effect, you should contact your doctor.
You can take Viagra with or without food, but it is better to take it on an empty stomach. If you consume a high-fat meal, you may find that this medicine takes a longer time to take effect.
Alcohol can prevent you from getting an erection, so avoid drinking heavily when taking this medication.
Grapefruit and grapefruit juice may interact with Viagra and affect the way it works. For your safety, avoid the use of Grapefruit products while taking this medicine.
Sildenafil is available in three different strengths:
Taking a dose of more than 100mg once daily will not increase the efficacy. It will, however, increase the risk of side effects.
Sildenafil is generally suitable for any adult male with ED. Although, it may not be appropriate for those who:
If any of these conditions apply to you, or if you have other medical conditions, contact your doctor to ask about other ED treatments.
Like all prescription drugs, Sildenafil (Viagra) can cause side effects. However, it is usually very well-tolerated and any reactions are mild and not long-lasting.
Sildenafil side effects include:
| Side effects | What to do |
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Most common:
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These generally pass by quickly as your body adjusts to the drug. |
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Common:
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Tell your doctor if they bother you. If you are dizzy, do not drive or operate heavy machinery. |
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Rare and more serious:
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Stop treatment and seek immediate medical attention. |
If any of these side effects become particularly concerning, please stop treatment and contact your doctor.
Sildenafil can interact with some medications. You should not take Sildenafil with medications containing nitrates, as your blood pressure could suddenly drop to an unsafe level. These medicines are often used to treat chest pain (angina).
This also includes recreational drugs such as “poppers” which contain amyl nitrite and butyl nitrite. A sudden drop in blood pressure could cause you to feel dizzy, faint, or have a heart attack or stroke.
Always tell your healthcare provider about any medications or supplements you are taking. This includes over-the-counter medications, herbal supplements, and vitamins, obtained without a prescription.
Many ED medications provide similar effects. This includes Tadalafil (Cialis), and Avanafil (Stendra). Sildenafil, the generic version of Viagra is a cheaper alternative and works in exactly the same way as the branded version.
Speedy Health offers a comprehensive selection of treatments for ED and related conditions.
Tadalafil (Cialis) is an alternative medication used to treat ED, it contains the active ingredient Tadalafil.
Cialis can provide effects that last up to 36 hours, which optimizes it for individuals engaging in more frequent sexual activity. You can take Cialis when required or once a day without regard to the timing of sexual activity.
You can buy Viagra or the more affordable version, Sildenafil, online from Speedy Health. You will need a prescription to make a purchase.
You will first complete a consultation form. Our board-licensed doctors, will then assess your health conditions and decide whether the ED treatment is suitable for you. The consultation is convenient and completely confidential.
If our doctors do not approve, you will not be charged. We will also explain the reasons why the medicine is unsuitable and suggest other treatments.
If our doctors approve, they will issue a prescription to our pharmacy. The pharmacy will dispense and dispatch your discreetly packaged order. The final result is your chosen ED treatment sent straight to your door.
Medically reviewed by Dr. Adrian Rawlinson
Written by our editorial team | Last reviewed January 05, 2026
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