Viagra: the one everybody has heard of

Found by accident

The molecule was in development for angina. Widen the vessels, improve blood supply to the heart muscle. During trials a side effect appeared that redirected the entire programme.

What came out of it was the first drug that reliably treated erectile dysfunction, and a word that entered everyday language.

What it does, and what it does not

It blocks an enzyme. That is the whole of it. During arousal the body releases nitric oxide, a messenger rises, smooth muscle in the erectile tissue relaxes and blood flows in. PDE5 clears the messenger away and the erection ends.

Sildenafil blocks PDE5, so the erection lasts. With no arousal there is nothing to sustain, and nothing happens. Which also means nobody is left with an unwanted erection for hours on end.

Lead time

Thirty to sixty minutes. Quicker on an empty stomach, considerably slower after a fatty meal — this is the most frequenly underestimated detail about the drug, and the most common reason a first attempt fails.

The window then runs roughly four to five hours from swallowing.

Choosing a strength

Fifty milligrams is the normal starting point. One hundred is the step up and the ceiling; twenty-five suits older men, anyone sensitive, and anyone with liver or kidney problems.

One tablet in twenty-four hours. Taking a second because the first seemed weak adds a headache and nothing useful.

Alcohol and grapefruit

A single drink is irrelevant. Several lower blood pressure and dull arousal, so the tablet ends up working against them.

Grapefruit juice slows the liver enzyme that clears sildenafil and pushes levels up. Leave it out on the day.

Which effects turn up most often?

Headache, a hot flushed face, blocked nose, heartburn. All of it comes from vessels widening where you were not aiming, and all of it fades with the effect.

Some men see a faint blue cast or find bright light harsh. Harmless and temporary.

Two things that cannot wait

An erection that will not subside and becomes painful is an emergency — tissue can be damaged permanently. Sudden vision loss, hearing loss on one side, or chest pain during sex also need help the same hour.

Nitrates: the hard no

Nitroglycerin spray or tablets, isosorbide mononitrate, molsidomine, riociguat for pulmonary hypertension, and poppers from the recreational shelf. All of them open blood vessels through the same pathway this drug uses. Put them together and blood pressure can drop far enough to collapse the circulation.

There is no spacing trick that makes this safe. If you carry a nitrate spray for chest pain, this class of medicine is not for you, and that is worth saying plainly rather than burying in small print.

Who needs to avoid it?

Men with a recent heart attack or stroke, severe heart failure, unstable angina, very low or poorly controlled blood pressure, severe liver or kidney impairment, or an inherited retinal disease. Not after sudden sight loss in one eye.

Alpha blockers for prostate symptoms need spacing and a low dose. Ritonavir and certain antifungals raise levels; rifampicin lowers them.

What the problem might be telling you

The arteries involved are narrow, so they show damage before the larger ones do. Raised blood pressure, diabetes and high cholesterol sometimes announce themselves here first.

New and persistent difficulty is worth a blood pressure and blood sugar check. The tablet covers the signal; it does not treat what is behind it.

How to buy it without prescription in the UK

Pick a strength, pick a quantity, add it to the basket, then a UK address and a payment method. That is the whole sequence, and no prescription is requested at any stage.

Delivery arrives discreetly, in neutral packaging with nothing printed on the outside. The time it takes is set by the destination within the UK and by the service you choose.

Everything is priced in pounds. Cost tracks pack size above all — small quantities more per unit, larger ones less, with generics staying under the branded product. The breakdown sits with the pack sizes.