Viagra-the much-publicised cure for sexual dysfunction-fails to work for more than half the men who take it, warn leading doctors.
They say the Health Service is wasting tens of millions of pounds every year on tablets, which don`t treat the cause of the problem.
Many of the men handed prescriptions by their GP are actually suffering from low testosterone levels, which cannot be treated by Viagra alone.
This is because the impotence pill depends on those using it having sufficient levels of the sex hormone for it to work.
Instead, doctors recommend that men should have a blood test to determine their levels of testosterone, which if found to be low, can be easily treated with relatively inexpensive testosterone pills, patches and gels.
Low testosterone affects 40 percent of the one in five men who suffer some form of impotence.
Although levels of the hormone start to decline with age, some are affected much earlier than others.
It can also be a symptom of an underlying health condition such as diabetes and heart disease, so experts say it is crucial that it is properly diagnosed.
Typical symptoms include tiredness, mood swings, insomnia - as well as low sex drive, the reason most will visit their doctor.
But sexual health experts warn that many GPs are prescribing Viagra by default rather than diagnosing the root cause of the problem.
Dr Geoffrey Hackett, a consultant urologist at Good Hope Hospital in Birmingham, and former chairman of the British Society for Sexual Medicine, said that more than half of men taking Viagra found it did not solve their problems adequately.
Men with sexual problems could be `wasting hundreds of pounds on tablets` when their real problem is low testosterone.
"Viagra will only work if there are sufficient levels of testosterone. Everybody thinks that Viagra is the panacea for all sexual problems, it`s not," the Daily Mail quoted Hackett as saying.
ANI
