Glucagon-like peptide 1 receptor agonists (GLP-1RAs) and dual gastric inhibitory polypeptide (GIP)/GLP-1RAs are used to improve glycaemic control in patients with type 2 diabetes mellitus; some of these drugs are also used to help with weight loss. In recent years, safety signals concerning a possible link between GLP-1RA therapies and hair loss have been emerging in the USA. The volume of prescriptions for these drugs in Europe is now increasing, and it can be expected that the number of cases of GLP-1RA-associated hair loss will therefore also increase in Europe over the coming years. In this commentary, we consider the pharmacological context and market expansion for GLP-1RAs, examine the evidence for an association between GLP-1RAs and hair loss, explore potential pathophysiological mechanisms, and propose clinical recommendations. Most evidence suggesting a potential association between GLP-1RAs and hair loss comes from pharmacovigilance database analyses and retrospective cohort studies. No prospective, controlled studies have specifically evaluated this issue. The evidence suggesting an increased risk of hair loss is strongest for semaglutide and tirzepatide. However, although cases of hair loss have been noted across diverse settings and multiple analyses, causality has not been established. One potential underlying mechanism is the rapid weight loss seen with these drugs, which could induce telogen effluvium. Further research is needed to evaluate causality, underlying mechanisms, the role of dosing and route of administration, and patient factors that may increase the risk. Clinicians need to be aware of the possibility of hair loss occurring with GLP-1RAs and patients should be informed about the potential risk and monitored for hair loss.
