Ozempic (semaglutide) carries several well-documented risks, ranging from common digestive problems that affect most users to rare but serious complications involving the pancreas, gallbladder, and thyroid. The drug’s FDA label includes a boxed warning, the most serious safety alert the agency issues, for a potential link to thyroid tumors. Understanding these risks helps you weigh them against the drug’s benefits for managing type 2 diabetes or weight loss.
Gastrointestinal Problems Are the Most Common Risk
Digestive side effects are by far the most frequent issue with Ozempic. In a two-year clinical study of people with overweight or obesity, 82.2% of those taking semaglutide experienced mild to moderate gastrointestinal problems, compared with 53.9% on placebo. Nausea, vomiting, diarrhea, and constipation are the most reported symptoms, and they tend to be worst during the first weeks of treatment and when your dose increases.
A more concerning digestive risk is severely delayed stomach emptying. Semaglutide works partly by slowing how fast food leaves your stomach, which helps you feel full longer. In some people, this effect becomes extreme. The FDA has received reports of gastroparesis (stomach paralysis) associated with semaglutide, and some of those cases had not resolved even after the patient stopped taking the drug. The medication’s label does not list gastroparesis by name, but it does warn about delayed gastric emptying.
In October 2025, the FDA updated Ozempic’s label with a new warning about severe gastrointestinal adverse reactions, signaling that regulators are taking these reports seriously. A separate label update in January 2025 added a warning about the risk of pulmonary aspiration during general anesthesia or deep sedation, because food remaining in the stomach longer than expected can be inhaled into the lungs if you go under. If you’re scheduled for surgery, your anesthesia team needs to know you’re on Ozempic.
The Thyroid Cancer Warning
Ozempic’s prescribing information carries a boxed warning about thyroid C-cell tumors. In animal studies, semaglutide caused these tumors in rodents. Whether it causes the same type of tumor, called medullary thyroid carcinoma (MTC), in humans remains unknown. The FDA notes that “the human relevance of semaglutide-induced rodent thyroid C-cell tumors has not been determined.”
Because of this uncertainty, Ozempic is completely off-limits if you have a personal or family history of MTC, or if you have a rare genetic condition called Multiple Endocrine Neoplasia syndrome type 2. You should be aware of symptoms like a lump or swelling in your neck, difficulty swallowing, hoarseness, or shortness of breath, which could signal thyroid problems.
Pancreatitis and Gallbladder Disease
Early concerns about GLP-1 drugs and pancreatitis prompted significant research. The picture that has emerged is reassuring but not entirely clear-cut. A meta-analysis of randomized clinical trials of semaglutide found no increased risk of acute pancreatitis compared with placebo. A large network meta-analysis covering more than 102,000 participants similarly found a neutral relationship between GLP-1 drugs and pancreatitis.
That said, some individual trials have shown slightly higher rates. The SCALE trial of liraglutide, a closely related drug, found acute pancreatitis in 0.4% of treated patients versus less than 0.1% on placebo. Semaglutide does raise levels of certain pancreatic enzymes during the first weeks of treatment, though those levels return to normal once the drug is stopped and don’t predict whether pancreatitis will develop. The practical takeaway: the risk appears low, but severe abdominal pain that won’t go away, especially if it radiates to your back, warrants immediate medical attention.
Gallbladder problems, including gallstones and inflammation of the gallbladder, are a recognized risk with GLP-1 drugs more broadly. Rapid weight loss from any cause increases gallstone risk, and the significant weight loss Ozempic produces likely contributes.
Eye Complications in People With Diabetes
If you have diabetes and already have some degree of diabetic eye disease, Ozempic can temporarily worsen it. This sounds counterintuitive for a diabetes medication, but it’s a known phenomenon with any treatment that lowers blood sugar quickly. When blood sugar drops rapidly after being high for a long time, the blood vessels in the eye that have adapted to high sugar levels can leak or swell. The American Academy of Ophthalmology notes this effect has been recognized for years, well before Ozempic existed.
This doesn’t mean Ozempic damages healthy eyes. The risk is specific to people who already have diabetic retinopathy, particularly those whose blood sugar has been poorly controlled. If that describes you, more frequent eye exams during the early months of treatment can catch problems before they become serious.
Muscle Loss During Weight Loss
When you lose a significant amount of weight on Ozempic, you don’t lose only fat. Research has consistently shown that semaglutide-induced weight loss includes reductions in lean muscle mass alongside fat mass. There is a silver lining: the ratio of lean mass to total body mass actually improves, meaning you lose proportionally more fat than muscle. But the absolute loss of muscle is real and matters, particularly for older adults or people with conditions that already put them at risk for sarcopenia, the clinical term for dangerous muscle wasting.
Resistance training and adequate protein intake are the primary strategies for preserving muscle while on Ozempic. This risk is not unique to semaglutide. Any form of significant calorie restriction or rapid weight loss carries the same trade-off, but it deserves attention because many people taking these drugs are not being counseled about exercise alongside their prescriptions.
Pregnancy Risks
Ozempic should be stopped at least two months before you plan to conceive. The drug has a long half-life, meaning it stays active in your body well after your last injection. Animal studies have shown potential harm to fetal development, including decreased fetal growth and major birth defects.
A systematic review of human pregnancies exposed to semaglutide found no clear increase in congenital anomalies when the drug was stopped within two months before or during early pregnancy. Preterm birth, large birth weight, and low blood sugar in newborns were observed, though researchers couldn’t firmly link these to the drug versus other factors. The evidence base is still small, and the precautionary two-month washout period remains the standard recommendation.
Suicidal Thoughts: A Cleared Concern
Early reports raised alarm about a possible connection between GLP-1 drugs and suicidal thoughts or behavior. The FDA investigated this thoroughly. Their meta-analysis covered 91 placebo-controlled trials and 107,910 patients and found no increased risk of suicidal ideation, self-harm, depression, anxiety, or other psychiatric events. A separate real-world study using healthcare claims data from over 2.2 million patients reached the same conclusion. Based on this evidence, the FDA in 2025 requested that manufacturers remove suicidal behavior warnings from the labels of GLP-1 medications that had included them.
Dangers of Compounded and Counterfeit Versions
Some of the most acute dangers associated with Ozempic don’t come from the drug itself but from unregulated versions. As of July 2025, the FDA had received 605 adverse event reports tied to compounded semaglutide. These products, sold by compounding pharmacies, bypass the FDA’s review process for safety, effectiveness, and quality.
Several specific problems have emerged. Some compounded versions use salt forms of semaglutide, such as semaglutide sodium or semaglutide acetate, which are chemically different from the active ingredient in approved Ozempic. The FDA has no data confirming these salts behave the same way in the body. Injectable products have arrived warm or without adequate cold packing, which can degrade the drug. Dosing errors have led to hospitalizations, both from patients measuring incorrect amounts and from healthcare professionals miscalculating doses. Some patients have been prescribed doses beyond what the approved label recommends.
Outright counterfeits are also circulating. The FDA has identified fake Ozempic products in the U.S. that could contain wrong ingredients, too much or too little active drug, or harmful contaminants. Fraudulent compounded products have appeared with labels listing pharmacies that either don’t exist or didn’t actually make the product. If you’re obtaining semaglutide from any source other than a major pharmacy filling a standard prescription, the risk profile changes dramatically.