The pills treat impotence

The drug's maker Pfizer says it is considering submiting an application to European regulatory authorities to clear it for sale in pharmacies.

An estimated 27 million men have already used the little blue pill for erectile dysfunction on prescription.

Medics said a change would be welcome but might mean other linked diseases were missed with no health check ups.

Ups and downs

Often, men with erectile dysfunction have underlying health problems such as diabetes, which can be spotted by their GP at the time they come for an anti-impotence prescription.

"If men can buy Viagra and rival anti-impotence drugs over-the-counter without a prescription, this opportunity is missed," said Dr David Ralph from the Institute of Urology at University College London.

But there would be benefits too, he said, such as combating the problem of Viagra sold illegally on the internet from unknown sources, which may be fake and if taken with some medicines could be fatal.

He said it would be safe to buy over-the-counter provided the pharmacist did the necessary checks to ensure the medication was suitable for the patient.

Embarrassment factor

It might also be a more attractive option to men as going to see the GP about sexual problems can be embarrassing, he added.

But he cautioned: "There is more to sexual relations than an erection. There may be other problems."

Viagra works by relaxing the blood vessels in the penis. This allows blood to flow into the penis causing an erection.

However, the drug is not an aphrodisiac and does not increase sex drive.

It is licensed only as a treatment for men who have been diagnosed by a doctor as having impotence.

Also, some men, such as those with severe heart disease or low blood pressure, should avoid it because of possible risks and side effects.

Viagra is not licensed for use in women and its safety in women has not been established.

A Pfizer spokesman said: "As with many of our products, Pfizer has routinely evaluated a number of options including different formulations, new indications, over-the-counter and continues to do so."

He added that despite speculation there were no plans to pursue a spray version of the drug.