The prescribing of testosterone for middle-aged women is “out of control” and may have long-term implications for their health, experts have warned. They are concerned that “testosterone evangelists” on social media – including some celebrities and GPs – are giving women the impression that the hormone will reduce fatigue and improve their energy levels, as well as protecting their heart, brain, muscles and bones. But experts say the evidence only supports its use in postmenopausal women with low libido, when psychosocial causes have been ruled out. “I genuinely think testosterone prescribing is completely out of control in the UK,” said Dr Paula Briggs, a consultant in sexual and reproductive health at Liverpool Women’s hospital and chair of the British Menopause Society. “People are being led to believe that they must have this. But we have no idea what long-term testosterone supplementation does to women.” Despite its reputation as a male hormone, testosterone is also produced in the ovaries and female adrenal glands, and it plays an essential role in the development and maintenance of female sexual anatomy, physiology and sexual response. Levels usually peak in a woman’s 20s and 30s, then gradually start to decline – probably due to waning production by the ovaries and adrenal glands, although stress, surgical removal of the ovaries, and certain drug or cancer treatments can also suppress its production. In the UK, National Institute for Health and Care Excellence (NICE) guidelines on menopause diagnosis and management say doctors can consider testosterone supplementation for menopausal women with low sexual desire if conventional oestrogen and progesterone-based hormone replacement therapy alone is not effective. According to British Menopause Society guidelines, this should only be considered once other causes, such as psychological or relationship issues, or medications, have been excluded. Even so, some private doctors are understood to be prescribing it as a first-line treatment for libido problems and other symptoms. For instance, in a recent Instagram live broadcast, Dr Louise Newson, a GP who runs a network of private menopause practices in the UK, claimed it was “barbaric and wrong that women aren’t able to access their own hormone” and that testosterone could improve mood, energy, concentration, stamina, as well as improve bone density and the way our muscles and cardiovascular systems work.” While many clinicians start HRT first and then add in testosterone, “increasingly I see women who are perimenopausal, their periods are still regular, and the majority of their symptoms seem to be related to testosterone deficiency [rather] than oestrogen deficiency”, Newson said. “For those women I might start only a very low dose of HRT and start testosterone in the first consultation.” Newson said: “Testosterone has a significant influence on brain processing and function so clinicians should stop thinking about it purely as a hormone to improve libido.” Prof Susan Davis, head of the Monash University Women’s Health Research Programme in Melbourne Australia, and a past president of the Australasian Menopause Society and the International Menopause Society, disputes this suggestion. She said: “The data clearly supports a trial of therapy in postmenopausal women with low sexual function that bothers them. But we have looked at the evidence inside and out, reviewed all the published literature, and published all of our own data. The evidence that testosterone will improve fatigue, wellbeing, cognition, or anything else you want to list, is just not there.” Briggs’ biggest concern is that women will accidentally end up with excessively high or “supra-physiological” levels of testosterone in their bodies, because of their hormone levels are not being closely monitored. “I’ve heard doctors saying it doesn’t matter if they are outside the normal range if the patient isn’t experiencing side-effects, but we don’t know what’s happening within their arterial system or even their heart,” says Briggs. “Men who use high-dose testosterone [to build muscle] in gyms get cardiomyopathy – where the muscle in the heart becomes weak and can’t pump – and some of them die, so it’s not nothing.” Prof Annice Mukherjee, a consultant endocrinologist at Spire Manchester hospital, and a media ambassador for the Society for Endocrinology, said she had seen patients with unpleasant side effects after being prescribed testosterone. “Women come to me saying: ‘My hair’s falling out’ or ‘My voice has got deeper, and I’ve got new acne or hair growth on my body, why is that?’ So, I measure their testosterone, and it is sometimes equivalent to a man’s level,” she said. One of her patients was a professional singer, who had been prescribed testosterone by a private clinic. “Her doctor had said: ‘You need HRT, and by the way, you also need testosterone.’ She came to me because she was experiencing problems with her voice. When I tested her testosterone levels, they were more than double what is normal for a woman,” Mukherjee said. “If we give women too much testosterone, it can affect their vocal cords. If you don’t mind your voice deepening a bit, that’s fine, but if you’re a singer, it can change your pitch.” Briggs and Dr Stephanie Faubion, medical director of the North American Menopause Society and director of the Mayo Clinic’s Women’s Health Research Center in the US, are also concerned about the lack of long-term safety data for testosterone use in women. “There’s a reason that we should be concerned about long-term safety, and that’s because we don’t have any data to say that it is safe,” said Faubion. “We don’t have data to say that it’s unsafe either. But the lack of data proving safety is a real problem.” Newson said long-term use of safely prescribed testosterone replacement was unlikely to be associated with any adverse health risks, “due to it being a natural hormone”. She added: “Testosterone should be prescribed in the right dose and type for any women who is likely to benefit from it with appropriate monitoring. More healthcare professionals should receive appropriate training and education about the safe prescribing of testosterone to help more women.”