Procedures to make 4-5's larger do not work, are “ineffective and risky”.

They also eave many men physically or psychologically scarred, research reveals.

An expert has told The Guardian that these surgeries should not even be done.

He says men were being exploited by “charlatans”.

There is “scant” evidence that the range of procedures men undergo in a bid to enlarge their penis actually produce that result, according to a review by British experts.

The treatments carry a high risk of complications, including permanent numbness, a review of the available evidence concluded.

And most men who undergo penile extension are dissatisfied with the results afterwards.

“[The review] found overall treatment outcomes were poor, with low satisfaction rates and significant risk of major complications, including penile deformity, shortening, and erectile dysfunction,” the authors said.

The findings are outlined in a new paper in the Sexual Medicine Reviews journal reporting an analysis by Gordon Muir, a urologist at King’s College hospital in London, and researchers at the Institute of Psychiatry, Psychology and Neuroscience at King’s College London.

“These procedures should almost never be done,” said Muir.

“They can cost up to £30,000 or even £40,000, often the man ends up with a penis that is disfigured and there is no more than 20% satisfaction rates with these procedures.”

The researchers reviewed 17 previous studies which assessed 21 different types of procedure, both surgical and non-surgical, performed on 1,192 men, in Britain and abroad.