What is Viagra, and who can use it?

Viagra is a prescription medicine for erectile dysfunction in men: "VIAGRA contains the active ingredient sildenafil (as citrate)" and "is used to treat erectile dysfunction, more commonly known as impotence, in men" (Viagra CMI). The European label limits it to adult men (EMA product information), and in Australia you need a prescription, after a doctor has assessed you (healthdirect). It is not for everyone: it must never be taken with nitrates, the medicines for angina. Who can take it is answered in what is Viagra and who can use it?; what it is for in what is the purpose of Viagra for men? and why do people use Viagra? The full list of who must not take it is in our safety guide.

How does Viagra work?

"It works by relaxing the blood vessels in your penis when you are sexually excited. This allows blood to flow into your penis, allowing you to get an erection in the natural way." (Viagra CMI). Sildenafil belongs to the phosphodiesterase type 5 (PDE5) inhibitors. During sexual stimulation the body releases nitric oxide, which raises a messenger called cGMP that relaxes the muscle of the penis and lets blood in; PDE5 breaks cGMP down, and sildenafil blocks PDE5 — which is why "sexual stimulation is required" for it to work (EMA product information). The step-by-step version is in how does sildenafil work on erectile dysfunction?, and the plain-English one in what is the “blue pill”, and how does it treat erectile dysfunction?

What it does not do matters as much. Viagra "will not increase your sex drive" (Viagra CMI), and healthdirect adds that sildenafil does not cure erectile dysfunction, protect from sexually transmitted infections or serve as contraception (healthdirect). How well it works is in our effectiveness guide.

What colour is Viagra, and what does the tablet look like?

Blue and diamond-shaped. The Australian leaflet describes each strength as "blue, rounded diamond shaped film coated tablets", debossed "VGR 25", "VGR 50" or "VGR 100" on one side and "VIAGRA" on the other (Viagra CMI). Every strength comes in a box of 4 tablets, and the 100 mg also in a box of 12 — more in how many tablets are in a pack of Viagra? Generic sildenafil need not look the same: generic medicines "may look different and have different filler ingredients" (healthdirect). The colour question is answered in what colour are Viagra pills?, with images in what does a Viagra pill look like? A tablet that does not match the leaflet is a warning sign — see how to tell real Viagra from a fake.

What is in Viagra?

Sildenafil citrate, equal to 25, 50 or 100 mg of sildenafil per tablet, plus inactive ingredients: microcrystalline cellulose, calcium hydrogen phosphate, croscarmellose sodium, magnesium stearate, hypromellose, titanium dioxide, lactose monohydrate, triacetin and indigo carmine. The leaflet names lactose as a potential allergen (Viagra CMI). More in what are the ingredients in Viagra? and what is Viagra's chemical name and composition?; whether "sildenafil citrate" differs from "sildenafil" is answered in is sildenafil the same as sildenafil citrate?

What is Viagra's medical name, and what does "Viagra" mean?

Its medical (generic) name is sildenafil; Viagra is a trade name, and "Other brands of the same medicine are also available" (healthdirect). Its class is the PDE5 inhibitors, and the European label files it under "Drugs used in erectile dysfunction" (ATC code G04BE03) (EMA product information). Under another trade name, Revatio, sildenafil treats pulmonary arterial hypertension (healthdirect). These questions have their own pages: what is Viagra's medical name and drug class?, what is sildenafil and how is it used?, what does the name Viagra mean? and, on how it began, what was Viagra originally for? Its other names around the world are in our guide to the names of Viagra.

What is the pink pill, or "female Viagra"?

Not Viagra: "Viagra is not for use by females. If you have heard about 'female Viagra', it is probably referring to a medicine called flibanserin (also known by its brand name, Addyi)." It "has been approved in the United States to treat premenopausal females who have low sexual desire", and "Flibanserin is not an approved prescription medicine in Australia" (healthdirect). More in what is the pink pill for women? and in our guide to women and ED medicines.

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