Can Ozempic or Mounjaro Cause Skin Cancer? What the Studies Show

There is no good evidence that semaglutide or tirzepatide cause melanoma or other skin cancers. Large studies comparing people who started a GLP-1 medicine with people who started other diabetes medicines found no increase in melanoma ^[5][6], and a pooled analysis of 50 randomized trials found no change in overall cancer risk ^[7].

That is reassuring, but it is not the same as proof of safety over decades. Skin cancers take years to develop, and these medicines have been used widely for weight loss only since the early 2020s. The sensible approach is the one that applies to every adult: know your skin, watch for new or changing spots, and have anything unusual looked at, whatever medicine you take.

The US prescribing information for Ozempic, Wegovy, Mounjaro and Zepbound does not list melanoma or other skin cancers among their adverse reactions ^[1][2][3][4]. The skin-related effects the labels do describe are different:

Injection site reactions such as redness, itching or discomfort where the pen is used ^[1][2][4]. Allergic reactions, including rash, hives and, rarely, serious swelling (angioedema) that needs urgent care ^[1][2][3][4]. Hair loss, listed among the common adverse reactions in the Wegovy and Zepbound weight-loss labels ^[2][4]. Changes in skin sensation, which the Wegovy label groups under dysesthesia and which include burning sensation, pain of skin and sensitive skin ^[2].

The boxed warning on these labels is about thyroid C-cell tumors seen in rodents, which is why people with a personal or family history of medullary thyroid carcinoma or MEN 2 should not use them ^[1][3]. It concerns the thyroid gland, not the skin, and has nothing to do with moles. If you are unsure whether a skin change is a side effect, ask your prescriber or pharmacist.

If a spot has caught your eye during treatment, our skin cancer checker describes the warning signs visible in a photo and suggests a next step. It is paid, it does not diagnose, and it does not replace a doctor.

UK cohort (Diabetic Medicine, 2024): researchers at McGill University compared 11,786 people with type 2 diabetes who started a GLP-1 receptor agonist with 208,519 who started a sulfonylurea. Melanoma rates were 42.6 vs 43.9 per 100,000 person-years, with no increased risk (hazard ratio 0.96) and no link to how long people took the medicine ^[5].

US target trial emulation (Diabetes, Obesity and Metabolism, 2026): using health records from 2014 to 2025, a University of Pennsylvania team compared GLP-1 starters with matched people starting two other diabetes drug classes, 235,797 pairs against SGLT2 inhibitors and 153,873 pairs against DPP-4 inhibitors. GLP-1 use was not associated with melanoma in either comparison (hazard ratios 1.04 and 1.09). Average follow-up was about two years ^[6].

Randomized trials (Diabetes, Obesity and Metabolism, 2025): a meta-analysis of 50 trials lasting at least a year found no significant difference in overall cancer. It found signals for thyroid and colorectal cancer that need more study, and no significant difference for any other cancer ^[7].

Most of these data come from people with type 2 diabetes and include older GLP-1 medicines as well as semaglutide. There is much less long-term data for tirzepatide, which was approved later.

Non-melanoma skin cancers (basal cell and squamous cell carcinoma) are far more common than melanoma, so studies can measure them more precisely.

In the UK cohort, rates were 243.9 vs 229.9 per 100,000 person-years, which was not a significant difference (hazard ratio 1.03) ^[5]. In the US study, there was a borderline increase compared with SGLT2 inhibitors (hazard ratio 1.06) but not compared with DPP-4 inhibitors, and the borderline result disappeared after a statistical check designed to catch hidden bias ^[6].

A few studies point the other way. A US records study of people with obesity reported fewer skin cancers over five years among GLP-1 users than among matched non-users (hazard ratio 0.62) ^[8], a genetic (Mendelian randomization) study suggested a lower basal cell carcinoma risk ^[9], and a 2026 report in Dermatologic Surgery described reduced melanoma and non-melanoma skin cancer rates in patients with obesity taking semaglutide or tirzepatide ^[10]. None of these were designed to prove protection, and no one should take a GLP-1 medicine expecting it to prevent skin cancer.

Association is not causation. Observational studies compare groups of people who chose or were prescribed different medicines, and those groups differ in ways that are hard to fully adjust for, such as weight, diabetes control, age, skin type and how much sun they get.

More doctor visits mean more diagnoses. People starting a new medicine often see their doctor more, and a skin cancer is more likely to be noticed and biopsied at a visit. This detection effect can make a medicine look linked to a cancer it does not cause.

Follow-up is short. Skin cancer usually develops over years of sun exposure, while most studies followed people for two to five years. Trials were not designed to look for cancer either: a 2026 review of 48 placebo-controlled trials in the Annals of Internal Medicine noted that the trials were not designed to evaluate cancer outcomes and had short follow-up ^[11].

The comparison matters. Most studies compared GLP-1 users with people on other diabetes medicines, not with people taking nothing, and results can differ depending on the comparison group.

Many people on a GLP-1 medicine say they suddenly see more moles. Losing weight does not make your body produce moles, but it changes the skin around them: skin that was stretched relaxes, folds that hid spots open up, and areas you rarely looked at become easy to see. Existing moles can look larger, flatter or a different shape on looser skin. Our guide to moles after Ozempic and rapid weight loss explains these changes and how to tell them apart from warning signs.

Skin tags (small, soft, skin-coloured flaps) are more common in people with excess weight and insulin resistance, often in the neck, armpits and groin. They are harmless, but a growth that bleeds, changes colour or keeps growing should be shown to a doctor rather than assumed to be a skin tag.

The rule is the same with or without a GLP-1 medicine: in adults, a spot that is new, changing, or looks different from your other moles deserves a closer look.

Do not stop or change your medicine because of skin cancer worries. If you have concerns about your risk, talk to the doctor who prescribed it; they can weigh your history and medicines together.

Check your skin once a month. Use a full-length mirror and a hand mirror, lift skin folds, and look at your back, scalp, soles and between your toes. As you lose weight, include areas you could not easily see before.

Track spots with photos. Take a dated photo of any spot you want to watch, in the same light and from the same distance, and compare it every month. Slow change is much easier to see side by side.

Keep up sun protection. Use broad-spectrum SPF 30 or higher on exposed skin, seek shade in the middle of the day, and wear a hat and clothing that covers your skin.

See a dermatologist if a spot is new, growing, changing in shape or colour, itching, bleeding or not healing, or if it looks unlike your other moles (the 'ugly duckling'). A full skin exam is also worth asking about if you have had skin cancer before, have a family history of melanoma, have many moles, are immunosuppressed, or have fair skin with a history of sunburns. Tell the dermatologist which medicines you take.

Ozempic, Wegovy, Mounjaro and Zepbound are trademarks of their owners and are named here only to identify the medicines. CheckMole is not affiliated with Novo Nordisk or Eli Lilly.