The male menopause is a myth, the symptoms more likely to be caused by laziness and an unhealthy lifestyle, researchers have claimed.
Heavy drinking could affect hormone levels
Some men claim symptoms such as hot flushes, depression and a lack of libido - similar to those experienced by women going through the menopause - are due to hormonal changes.
But US researchers said they were more likely to be caused by men's unhealthy habits, such as weight gain, smoking and too much drinking.
Conditions such as diabetes, heart disease and depression probably also have more of an impact on levels of testosterone than ageing, they said.
Professor John McKinlay, dismissed the male menopause as a "myth", and said drug companies were cashing in on some men's belief that they need hormone replacement therapy.
He told a joint conference of the British Fertility Society, the British Andrology Society and the Society for Reproduction and Fertility in Aberdeen he had carried out research which showed men did not suffer the same drop in hormone levels as women in middle age.
Professor McKinlay, from the New England Research Institutes in Watertown, Massachusetts, looked at data from the Massachusetts Male Ageing Study (MMAS) which looked at 1,700 men.
He said male hormones levels only declined gradually with age, by about 1% a year, and there was no evidence for the existence of a syndrome.
Around 5% of men showed signs of hypogonadism, a clinical loss of hormones which is not connected to middle age.
Professor McKinlay said: "The notion of a male menopause, mid-life crisis or andropause has
been discussed for several decades.
"Worldwide, male ageing is generating public interest and also, incidentally, a lucrative market. "
He added: "Pharmaceutical involvement is producing new treatments, such as testosterone replacement, in search of a disease."
Professor McKinlay added that many "non-scientific" books had been written about the male menopause, but warned they used self-selected data and misrepresented research to back up their ideas.
But Dr Malcolm Carruthers of the Andropause Society, who runs a clinic which offers testosterone treatment attacked the study.
He told BBC News Online: "This type of propaganda being put out is denying many men who desperately need testosterone replacement therapy.
"Far from trying to set up exclusively in private practice, what we are actively trying to do is make it available on the NHS, in the same way as women's hormone replacement therapy is."