Penis enlargement surgery rarely works and should almost never be performed, doctors have warned.

Researchers found as many as 80 per cent of men who have the ops are unhappy with the results, and many are left with 'disfigured' or even smaller penises.

Private clinics are preying on men insecure about their bodies, one expert claimed, with the 'vast majority' of paying customers already having normal sized penises.

The most popular penis enlarging procedures are filler injections to make it thicker and surgery to snip a ligament at the top which makes it appear longer.

But both carry a high risk of complications, a study has warned, and are rarely worth the effort or the money – costs can rise as high as £40,000.

King's College London scientists found men who opt for penis enlargement procedures almost always have normal sized penises beforehand and are unhappy afterwards (stock image)

Researchers from King's College London looked at past studies into the outcomes of 1,192 penis enlargement procedures done on men around the world.

'Overall treatment outcomes were poor, with low satisfaction rates and significant risk of major complications,' they said.

The major complications included 'penile deformity, shortening, and erectile dysfunction'.

Others were left with penises which were permanently numb in places, scarring, psychological problems or regret.

Gordon Muir, a urological surgeon at London Bridge and Kings hospitals, helped to lead the research.

He told The Guardian: 'These procedures should almost never be done.

'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 per cent satisfaction rates with these procedures.'

WHAT TYPES OF PENIS ENLARGEMENT ARE THERE? There are various surgical and non-surgical procedures which can be used to try and increase the size of a penis. One treatment which is said to be becoming more popular is the use of dermal fillers. These work in the same way as lip fillers and are injected into the shaft of the penis to make it thicker. They are temporary and the filler is absorbed by the body after a few months. Vacuum pumps can be used to try and increase penis length or girth but, according to a study by Kings College London, do not work. Surgically, a popular option is an operation called a suspensory ligament incision. This involves snipping a ligament which connects the penis to the body at the top of the base. Cutting this cause the penis to droop more, appearing longer when flaccid – but the op doesn't actually add any length to the penis. In other procedures, tissue grafting can be used to add fat or other tissue from different parts of the body to the penis. Advertisement

Trying to increase the penis size of men who are normally endowed is a procedure which has barely any evidence to back it up, the study said.

The procedures aren't offered on the NHS except if someone's penis is damaged in a traumatic accident – cosmetic operations are paid for privately.

Mr Muir warned some of those running the clinics were 'charlatans' and didn't carry out due diligence before going ahead with the life-changing surgeries.

'Many men who wish to undergo penis enlargement procedures have an average-sized penis but believe their size to be inadequate,' he added.

'Sadly, some clinics seem to ignore this. Surgeons in the private sector should not do this. It’s wrong on every level.'

The researchers said men should always be offered full counselling and a psychological assessment before they decide to have the therapy.

In the study they added: 'These findings make recommending surgery for men with normal penile dimensions unscientific at best and unethical at worst.'

They argued having a bigger penis size has long been associated with being more masculine and better in bed – despite no evidence to prove either.

And, despite 85 per cent of women reportedly being happy with their partner's penis size, around half of men wish theirs was bigger.

'Nowadays, pornography is often used as a benchmark and reinforces the belief that sexual fulfilment depends largely on penis size,' the researchers said.

'These concerns can cause significant distress even in men with a normal-sized penis.'

In their study the scientists looked at men who had non-surgical procedures such as dermal fillers injected to make the penis thicker, or using vacuum pumps.

Fillers are becoming more common in the UK, with private clinics Moorgate Aesthetics and Androfill revealing in October that they received 700 calls per month – up from around 10 per month three years ago.

The procedure costs around £3,000 per session but the injections are only temporary.

And they studied surgeries including having a ligament at the top of the penis snipped to make it hang lower, or having tissue from elsewhere grafted onto the penis.

Surgery can sometimes actually make the penis shorter because scar tissue causes it to tighten up and shrink.

The research was published in the journal Sexual Medicine Reviews.