GLP-1 Medications and MCAS: 89% Reported Improvements

GLP-1 medications for MCAS are an emerging area of research that could offer a new treatment approach for some people with mast cell activation syndrome (MCAS). This type of medication is best known for helping with blood sugar, appetite and weight. However, researchers are increasingly discovering that they may also affect inflammation and the immune system. This has raised the question of whether they could also help with mast cell activation.

There are already several medications that may be used to manage MCAS symptoms, including antihistamines, montelukast and cromolyn sodium. But MCAS can look very different from one person to another. A treatment that works well for one person may provide little relief for another. This is why researchers continue to look for additional treatment options.

What are GLP-1 medications and how do they work?

GLP-1 medications mimic a hormone called glucagon-like peptide-1 (GLP-1), which our body naturally produces after we eat. This hormone helps regulate blood sugar and appetite.

GLP-1 medications, also called GLP-1 receptor agonists (GLP-1 RAs), act on cells that have receptors for GLP-1. They can:

• increase insulin release when blood sugar is elevated
• reduce the release of glucagon, a hormone that raises blood sugar
• slow down how quickly food leaves the stomach
• increase feelings of fullness and reduce appetite

This is why medications such as semaglutide (Ozempic and Wegovy) and tirzepatide (Mounjaro and Zepbound) are used for conditions such as type 2 diabetes and obesity.

However, GLP-1 receptors are found in many parts of the body. GLP-1 medications therefore appear to have effects that go beyond blood sugar and appetite, including possible effects on inflammation and the immune system.

Why might GLP-1 medications help with MCAS?

Mast cells are immune cells that play an important role in inflammation and allergic reactions. When they become activated, they can release hundreds of different substances, including histamine, leukotrienes, prostaglandins and cytokines.

Researchers have found evidence that GLP-1 signalling can influence mast cells in experimental models. However, there is still some uncertainty about whether human mast cells consistently have functional GLP-1 receptors. In other words, we don’t yet know exactly how GLP-1 medications might affect mast cells in humans.

If GLP-1 medications do help people with MCAS, the effect might also be indirect. These medications can affect inflammation, metabolism and the gastrointestinal system, all of which could potentially influence mast-cell-related symptoms.

What does the research show?

There is currently very little clinical research specifically investigating GLP-1 medications for MCAS, but the first findings are certainly interesting.

The most significant study so far, published in 2025, looked at 47 people with MCAS who had been treated with different GLP-1 medications. The authors reported that 89% experienced some clinical benefit, with improvements reported across a wide range of MCAS-related symptoms.

Some of the individual cases are particularly interesting. Several patients reported improvements within hours or days of starting treatment. This is much faster than would be expected from weight loss alone. Some patients also received GLP-1 medication specifically for their MCAS symptoms rather than for diabetes or obesity. This raises the possibility that GLP-1 medications could have effects beyond their well-known effects on body weight and blood sugar.

The study also included people who did not have a higher body weight. BMI values ranged from 20 to 66, suggesting that the reported improvements were not exclusively seen in people with a higher body weight.

However, these results need to be interpreted carefully. This was a retrospective case series, meaning the researchers looked back at patients who had already been treated in clinical practice. There was no placebo or control group, and the study did not use the kind of standardized measurements that would allow us to determine exactly how effective the treatment is. The authors therefore conclude that randomized controlled trials are needed to properly establish whether GLP-1 medications are effective for MCAS and to determine the appropriate dose.

What about chronic hives?

A separate 2026 report described two women with chronic spontaneous urticaria (CSU), a condition in which mast cells play a central role in causing recurrent hives. Both women had longstanding CSU that had not been adequately controlled with high-dose antihistamines or other medications. After starting a GLP-1 medication, both women experienced a substantial improvement in their hives within three weeks, with the improvements lasting for months.

The two cases are particularly interesting because neither patient had obesity when treatment began. One had a BMI of 24.2 and the other a BMI of 28. The first patient’s hives completely resolved within three weeks of starting oral semaglutide. The second experienced a marked reduction in hives within three weeks of starting tirzepatide.

The authors suggest that the relatively rapid improvement could point towards an effect on inflammation or possibly mast-cell activity. At the same time, they acknowledge that other explanations are possible, including changes in metabolism, diet, the gut and gut microbiome, and weight loss. They specifically note that the improvement could even have been coincidental.

Of course, two cases cannot establish that GLP-1 medications treat chronic hives or MCAS. But together with the larger MCAS case series, they provide an interesting reason for researchers to investigate the connection further.

Could GLP-1 medications help people who don’t have a higher body weight?

This is an interesting question because GLP-1 medications are most commonly prescribed for people with type 2 diabetes or obesity.

The MCAS study included people with BMI values ranging from 20 to 66. The two patients in the chronic hives report had BMIs of 24.2 and 28 when they started treatment. This means that neither had obesity.

This doesn’t prove that any potential benefits are unrelated to weight loss or metabolic changes. However, it suggests that the possible effects of GLP-1 medications may be worth investigating even in people who don’t have higher body weight.

Is GLP-1 medication a treatment for MCAS?

Not yet. The research is interesting, but it is still at a very early stage. There are currently no randomized controlled trials showing that GLP-1 medications are an effective treatment for MCAS. We also don’t yet know which people might benefit, what dose would be appropriate, or exactly how these medications might affect mast cells.

GLP-1 medications also have their own potential side effects, particularly digestive symptoms such as nausea, vomiting, diarrhoea and constipation. More serious side effects are possible as well, so these medications should only be used under appropriate medical supervision.

For now, GLP-1 medications should be viewed as an interesting area of emerging research rather than an established MCAS treatment.

The early observations are nevertheless worth watching. If future controlled studies confirm that GLP-1 signalling can influence mast cell activation, these medications could potentially become another treatment option for people with mast-cell-related conditions who don’t get sufficient relief from existing treatments.

References

• Afrin, L. B., Weinstock, L. B., Dempsey, T. T., Aschenbrenner, K., Blitshteyn, S., & Schofield, J. R. (2025). Utility of glucagon-like-peptide-1-receptor agonists in mast cell activation syndrome. The American Journal of the Medical Sciences, 370(4), 377–382. https://doi.org/10.1016/j.amjms.2025.07.006
• Kwiek, B., Sieczych, J., Łukowska, K., & Ambroziak, M. (2026). Improvement of chronic spontaneous urticaria after Glucagon-Like peptide 1 receptor agonist therapy: report of two cases. Dermatology and Therapy, 16(2), 1419–1425. https://doi.org/10.1007/s13555-025-01640-7