How does the alcohol pill Nalmefene work?

The alcohol pill, known as Nalmefene, is administered orally once a day and is taken when people feel the urge drink.

It works by blocking the part of the brain which gives drinkers pleasure from alcohol, stopping them from wanting more than one drink.

Men would qualify to receive the treatment if they consume 7.5 units of alcohol per day - around three to four pints of standard strength lager.

It would be offered to women who consume five units a day, which amounts to around half a bottle of wine.

Nalmefene is the only licensed medicine which helps people reduce their drinking rather than aiding them to stop drinking altogether.

Severe alcoholics and those who are able to cut down without help would not be eligible for the drug.