People who start Ozempic-style weight-loss and diabetes drugs are more likely to be diagnosed with hair loss than people starting other diabetes medicines, according to research published in The BMJ and reported by Medical Republic on October 26, 20261. The drugs belong to a class called GLP-1 receptor agonists, medicines that mimic a gut hormone involved in appetite and blood sugar. An Australian dermatologist also raised a question the study cannot answer: whether the shedding that often comes with weight loss is always temporary1.
What the new study found
The BMJ study looked at adults with type 2 diabetes who started one of several types of glucose-lowering medicines1. Those who began a GLP-1 drug had a 37% higher relative risk of alopecia, the medical word for hair loss, than those who began an SGLT-2 inhibitor, another class of diabetes medicine1. Compared with people starting a DPP-4 inhibitor, a third class, the relative risk was 68% higher1.
The link was clearest for non-scarring hair loss, the kind where the hair follicle is not destroyed and regrowth is possible1. The absolute risk, meaning the chance that any one person loses hair, remained low, according to the report1. The coverage did not give the number of patients or the absolute figures.
The researchers used electronic health records. They set up the comparison to mimic a clinical trial on paper, a method called target trial emulation, to reduce the effect of other differences between patients1. Even so, the study could not establish whether the drugs directly caused the hair loss1.
The evidence so far
The BMJ findings add to earlier work pointing the same way1. A team at George Washington University analysed records from a US network of 67 healthcare organisations covering more than 100 million patients, from 2014 to 20242. They compared adults who had at least two prescriptions for drugs including semaglutide, liraglutide, dulaglutide and tirzepatide with matched people who were not on these drugs, about 548,000 in each group2. People with prior hair loss or other likely causes, such as thyroid disease, menopause, malnutrition, chemotherapy or weight-loss surgery, were left out2.
At 12 months, the drug users had higher odds of three diagnoses2:
- Telogen effluvium, sudden shedding after a shock to the body: 76% higher odds2.
- Androgenetic alopecia, pattern hair loss: 64% higher odds2.
- Non-scarring hair loss overall: 40% higher odds2.
Alopecia areata, an autoimmune form of hair loss, was not significantly different between the groups2. In a February 2026 announcement, the university said its findings held regardless of age, sex, body weight and diabetes status, and argued that the distinct patterns suggest the risk may not be explained by dieting alone3. The study authors also noted that reports to drug-safety databases in the US and internationally had shown higher odds of hair loss with semaglutide and tirzepatide2.
What it does not show yet
Neither study shows why hair loss is more common. Rapid weight loss is a known trigger for telogen effluvium, and eating too little, especially too little protein and iron, may also disrupt the hair growth cycle1. The George Washington authors listed rapid weight loss, hormonal and metabolic shifts, and a possible direct effect on the follicle, since hair follicles carry the receptor these drugs act on, as proposed explanations2. Those are ideas, not findings.
Professor Rod Sinclair, an Australian dermatologist with a special interest in hair loss, put the open questions this way1:
“The question with the GLP-1s is whether it is the drug, or the weight loss, or the protein malnutrition that causes the increased hair shedding?”
Health-record studies also depend on hair loss being diagnosed and coded by a doctor. The George Washington team defined hair loss using standard diagnosis codes2, so cases that were never recorded would not be counted.
Is the shedding always temporary?
This is the question Sinclair raised. Telogen effluvium has historically been considered reversible, while androgenetic alopecia is progressive and needs ongoing treatment1. Sinclair said emerging research suggests telogen effluvium could start pattern hair loss rather than simply reveal thinning that was already there1. He suggested heavy shedding might deplete a group of stem cells around the follicle that is needed to rebuild the hair’s growth base1.
That proposed mechanism has not been shown in people on these drugs, and further research is needed to establish whether it happens1. Sinclair called for a comprehensive review of the evidence linking the drugs, changes in nutrition, shedding and pattern hair loss1.
Dr Caroline Phegan said the two conditions can occur together. “A woman may experience telogen effluvium following significant weight loss, whilst also having underlying female-pattern hair loss that was previously less noticeable,” she said1. Telogen effluvium usually shows up as shedding across the whole scalp, often two to four months after a trigger, while female-pattern hair loss involves gradual thinning at the centre of the scalp and crown1. Whether weight loss reveals an existing condition or triggers a new one remains unresolved1.
Who is behind the research and comments
The funding and author ties of The BMJ study were not described in the coverage available to Biohack. The George Washington analysis was led by dermatology researchers at the university and Children’s National Hospital in Washington2. One author, Yagiz Matthew Akiska, disclosed a travel grant from the National Alopecia Areata Foundation to attend a 2025 dermatology congress2.
Dr Phegan is chief medical officer of Ashley & Martin, a company that sells hair loss treatment1. She said the evidence so far suggests “it’s likely a combination of factors rather than a direct effect of the medication alone”1. She also said hair shedding does not automatically mean the drug should be stopped, and that decisions depend on why the drug was prescribed, diet, the speed of weight loss and overall health1.
How it fits the wider picture
GLP-1 drugs are widely prescribed for type 2 diabetes and obesity because of their effects on metabolism and the heart2, and George Washington University noted they are used by millions of Americans3. Hair loss matters partly because it is distressing and can affect whether people keep taking a medicine, the university said3. Its researchers recommended that people starting these drugs be told about the possible risk, and that new shedding prompt checks of nutrition and hormones2.
The picture is not one-directional. Case reports have described improvement in some rare scarring forms of hair loss in people taking these drugs, which the George Washington authors said points to complex biology2. Biohack has also covered separate research on these medicines, including a trial of Ozempic’s active drug and lab measures of aging, and a different form of hair loss treated with the arthritis pill Rinvoq.
What to watch next
- Whether the full BMJ paper’s absolute numbers and patient counts get wider attention, since the relative risk alone can make a small risk sound large.
- Whether anyone takes up Sinclair’s call for a comprehensive review of the evidence1.
- Studies that separate the effect of the drug itself from fast weight loss and low protein or iron, the central unanswered question1.
- Longer follow-up showing whether shedding in people on these drugs recovers fully. Phegan said recovery can be slow, with shedding taking several months to settle1.
