Viagra is set to become available over the counter for the first time in the UK as manufacturer Pfizer wrestles with dwindling sales of the drug.

The US giant hopes the imminent release of its over-the-counter product – called Viagra Connect – will help make up for flagging sales of prescription Viagra in the face of competition from copycat rivals.

Global sales were $1.2bn (£850m) last year, down almost half on $2.1bn five years earlier.

The Viagra Connect product could also prove an asset for Pfizer’s consumer healthcare division, which it has been struggling to sell after both GSK and Reckitt Benckiser pulled out of the $20bn contest to buy it last week.