Blockbuster weight loss drugs, initially developed for diabetes, are gaining widespread use for their ability to suppress appetite and facilitate rapid weight loss. However, alongside their intended effects, these medications, such as Mounjaro and Wegovy, are revealing a spectrum of unexpected side effects, including significant changes in sexual desire and hair loss. Dr. Shashi Prasad, a GP and women's health expert at The Marion Gluck Clinic, highlights that while issues like nausea and organ damage have been reported, alterations in libido remain less understood but are increasingly observed.

One intriguing side effect reported by some users is a soaring sex drive. Dr. Prasad suggests several factors may contribute to this. Firstly, body fat is known to cause chronic, low-level inflammation, which can reduce sex drive. As weight loss jabs reduce fat, they may alleviate this inflammation, thereby boosting libido. Secondly, Mounjaro mimics GLP-1, a gut hormone that regulates blood sugar and suppresses hunger. Dr. Prasad posits that GLP-1's impact on certain brain chemicals could directly enhance sexual desire. Furthermore, users often report a decreased interest in alcohol. Since alcohol is a depressant that can dampen sex drive, its reduced consumption may contribute to an increased libido. Improved body image and a subsequent boost in confidence following weight loss also play a significant psychological role in enhancing sexual desire.

Conversely, some individuals report a reduction in sex drive while on these medications. Dr. Alexis Bailey, a neuropharmacologist, explains that GLP-1 injections may suppress the production of dopamine, the brain's 'feel-good' chemical associated with pleasurable experiences like food, alcohol, and sex. This dampening of dopamine surges can lead to a significant drop in libido, even as users feel more confident about their new bodies. Dr. Prasad also notes that rapid weight loss or a restricted diet can unbalance hormones, specifically reducing levels of testosterone and estrogen, which are crucial for sexual desire. She advises users to discuss concerns about their sex drive with their doctors, as it could be due to fatigue from a calorie deficit or an overly high drug dose affecting the nervous system and dopamine production. Emphasizing a balanced, nutrient-dense diet and regular exercise can trigger endorphin release and potentially improve sexual desire.

Another distressing side effect reported by many users is dramatic hair loss. Since Mounjaro's approval for obesity treatment in February 2024, reports of thinning, lacklustre hair have proliferated on social media platforms like Reddit. Experts like Dr. Ed Robinson, who runs an aesthetics clinic, attribute this hair loss not directly to the drug itself, but to the rapid weight loss and resulting nutritional deficiencies. GLP-1 medications reduce appetite by silencing 'food noise,' leading many users to eat significantly less and often make nutritionally poor food choices. This sharply reduced calorie intake can lead to quick deficiencies in essential nutrients like proteins, fats, vitamins (D, A, K, E), iron, biotin, and magnesium, all vital for hair strength and formation. Dr. Robinson highlights that supplements are not a substitute for a balanced diet, as fat-soluble vitamins require dietary fat for absorption, which is often lacking in restricted diets.

Moreover, Dr. Robinson explains that severe calorie restriction can trigger a hair loss condition called telogen effluvium, where the body sheds a substantial amount of hair due to stress, shock, or malnutrition. This accelerates the resting phase of the hair growth cycle, causing hairs to detach and fall out without sufficient nutrients for new hairs to grow, leading to baldness and thinning patches. Women undergoing perimenopause and menopause, a significant demographic for weight loss jabs, may experience even more extreme hair loss due to hormonal changes. Both Dr. Prasad and Dr. Robinson stress the critical importance of using weight loss medication under strict medical supervision. Doctors should assess diet and adjust doses if weight loss is too rapid. For hair loss, preventative treatments like Minoxidil or other non-surgical options can help, but addressing the underlying nutritional deficiencies and dose adjustments are paramount. These conversations underscore the need for more research and open dialogue between patients and healthcare providers regarding the comprehensive impact of these powerful medications on overall well-being.