Unknown Side Effects of GLP-1 Drugs: Nail Split and Scalp Inflammation

The first controlled clinical study on the unknown side effects of GLP-1 receptor agonist drugs (semaglutide and tirzepatide derivatives), which has become a global phenomenon in the treatment of obesity and type 2 diabetes in the world of medicine and dermatology, has been concluded.

The research, which was announced to the public at the European Academy of Dermatology and Venerology (EADV) Congress 2026, included 575 GLP-1 users from France, the USA, Brazil and Mexico and 1,329 diabetes and obesity patients who had never used the drug.

NAIL SEPARATION REACHED 39 PERCENT: DISCOLOUR AND TISSUE LOSS

According to clinical trial data, 66% of GLP-1 drug users experienced at least one dermatological nail disorder. While a case of separation of nail tissue from flesh (onylolysis) was detected in 39% of the participants, this rate remained at 9% in the control group that did not use the drug.

In addition, the rate of significant color change and deformation in the nail was measured as 46% in those using the drug. Experts noted that nail damage is not only caused by rapid weight loss, but also that drug use is a direct determinant in the analyzes made specifically for weight loss patients.

SCALP INFLAMMATION IS BEHIND HAIR LOSS

In the parallel part of the study, hair and scalp tissues of GLP-1 patients were examined. Unusual hair loss was detected in 50% of the patients using the drug, and loss of hair volume and density was detected in 42%.

Study author Dr. Bruno Halioua declared that shedding, unlike the classic weight loss shedding, involves an "inflammation of the scalp" with redness, itching and flaking. It was emphasized that this inflammatory process on the scalp is a treatable clinical condition.

VITAL WARNING FROM EXPERTS TO PATIENTS: "DO NOT STOP THE MEDICATION BY YOURSELF"

The dermatologist who conducted the research, Dr. Charles Taïeb and Dr. Bruno Halioua made an important warning, stating that the findings should not cause panic.

Experts state that the observed nail separation and hair loss are generally benign; He announced that patients should not discontinue an effective obesity treatment at their own discretion without consulting their physicians, and that the resulting dermatological symptoms can be controlled with supportive treatments.