For people using GLP-1 drugs, weight may not be the only thing changing. Two new studies link use of the medicines to unexpectedly common reports of hair loss, reduced hair volume, nail detachment, and nail discoloration.

The studies were presented Wednesday at the annual meeting of the European Academy of Dermatology and Venereology in Vienna. Both examined the same 1,904 participants who had obesity, type 2 diabetes, or both.

Among the full group, 575 participants said they were taking GLP-1 drugs. Researchers compared their reports with those from participants who had never used the medicines.

The findings covered a widely prescribed class of drugs used to treat obesity and type 2 diabetes. The class includes Ozempic, Wegovy, Mounjaro, and Zepbound.

One study concentrated on nail disorders and identified substantial differences between users and nonusers. Overall, 66% of participants taking GLP-1 drugs reported a nail disorder, compared with 53% of those who did not take the medicines.

Nail detachment produced one of the most striking comparisons. Participants using GLP-1 drugs reported the problem more than four times as often as other participants with obesity or type 2 diabetes who had never used the drugs.

Discoloration also appeared more frequently among participants taking the medicines. It was reported by 46% of GLP-1 users, compared with 17% of nonusers.

The second study focused on hair related changes. Half of the participants using GLP-1 drugs reported unusual levels of hair loss, while 34% of participants who had never taken the medicines reported the same problem.

Researchers also examined changes in hair volume and density. Those decreases were reported by 42% of participants taking the weight loss drugs, more than twice the 19% reported among participants who had never used them.

Together, the findings describe a pattern in which hair and nail complaints were reported more often by GLP-1 users. The studies did not establish that the drugs caused those reported conditions.

The results relied on comparisons between participants who said they were taking GLP-1 medicines and those who had never taken them. All participants in the two studies had obesity, type 2 diabetes, or both.

The nail findings extended beyond the especially large difference in reports of detachment. When every reported nail disorder was considered together, the difference between users and nonusers was 13 percentage points.

The hair findings showed a similar divide across multiple measures. Reports included unusual hair loss as well as declines in hair volume and density, with the GLP-1 group recording higher figures for both comparisons.

Despite the size of some differences, the researchers urged caution about interpreting the results. They said the findings should be considered preliminary until they are published in a peer reviewed journal.

For now, the studies add hair and nail concerns to the discussion surrounding GLP-1 use without proving a causal relationship. Their findings rest on reports from 1,904 participants, including 575 users of the increasingly prescribed medicines.