Weight-loss medications, such as Mounjaro and Wegovy, originally developed for diabetes management, have gained widespread recognition for their efficacy in promoting rapid weight loss by curbing appetite. While their more commonly discussed side effects include nausea, constipation, and in rare severe instances, life-threatening organ damage, a new concern has emerged regarding their potential impact on patients' libidos.

Experts are now pinpointing a drop in sex drive as another consequence of these popular injections. Contrary to initial thoughts that this might stem from uncomfortable physical side effects like bloating or fatigue, a growing consensus suggests a more direct neurological mechanism. The injections primarily function by mimicking GLP-1, a hormone released by the gut after eating, which plays a crucial role in regulating appetite. Research indicates that these drugs also significantly influence dopamine release, a key neurotransmitter involved in reward and motivation pathways in the brain.

Dr. Ryan Sultan, an assistant professor of clinical psychiatry at Columbia University, explains that sex drive and food acquisition drives share many overlapping neuronal networks. He states, "When we take GLP-1s, we are essentially dampening the internal processes that drive us to address our evolutionary needs." By inhibiting the pathways associated with seeking food, these medications consequently affect the interconnected systems that drive sexual desire. Dr. Bronwyn Holmes, a doctor and hormone specialist at Eden weight loss clinic, corroborates this view, noting that these drugs "dampen dopamine-driven reward signals." While beneficial for reducing food cravings and other compulsive behaviors, this dampening can indirectly impact mood, motivation, and other reward-driven activities, including intimacy or even alcohol consumption.

Dr. Kent Berridge, a professor of psychology and neuroscience at the University of Michigan, further elaborated on this, suggesting that if dopamine activation, particularly in the nucleus accumbens (a brain structure vital for pleasure, reward, and addiction), is suppressed, it could plausibly diminish sexual desire, which is naturally a 'peak' experience. He remarked, "It may be partly acting right on the nucleus accumbens, because there are receptors there."

For individuals experiencing such side effects, Dr. Holmes offers reassurance that libido or mood-related changes are often reversible upon discontinuing the medication. However, the exact timeline and completeness of this reversal can vary based on individual factors and the presence of other health considerations. Beyond libido, a British study published in QJM: An International Journal of Medicine last year also highlighted that new patients on GLP-1 drugs might experience cognitive changes in their decision-making processes, partly attributed to the induced calorie deficit and the direct effects of GLP-1 on brain function.

The scale of GLP-1 drug usage is substantial, with approximately half a million NHS patients and some 15 million patients in the US currently utilizing these weight-loss jabs. Private usage numbers are even higher. In the UK, Wegovy is prescribed to around 35,000 patients in specialist weight management clinics, while Mounjaro has been available in similar clinics since March and is now also prescribable by GPs.

This emerging concern about drug-induced libido reduction comes amidst broader discussions about a global "sex crisis." Recent surveys indicate a decline in sexual activity, with over a quarter of Britons reporting less sex than before, and one in six admitting to no sexual activity for an entire year. The average adult is reported to have sex only 46 times annually. Given that sex and intimacy are linked to numerous health benefits, including improved heart health, stress reduction, and enhanced mental well-being, the potential impact of widely used medications on libido warrants further extensive research and patient counseling.