Ozempic (semaglutide) is generally well tolerated, but long-term use carries several potential side effects beyond the nausea and digestive upset most people experience in the first few months. Some are mild and manageable, while others are rare but serious. Here’s what the evidence shows across years of use.
Gastrointestinal Problems That May Persist
Nausea, vomiting, and diarrhea are the most common side effects when starting Ozempic, and for most people they fade within weeks as the body adjusts. But semaglutide works partly by slowing how fast your stomach empties, and in some people this effect becomes extreme. Users face a 3.67 times higher risk of gastroparesis, a condition where the stomach essentially becomes partially paralyzed and struggles to move food into the small intestine. Symptoms include persistent nausea, vomiting, bloating, and abdominal pain that doesn’t resolve with dose adjustments.
The FDA has also added intestinal obstruction, ileus (where the bowel temporarily stops moving), and severe constipation including fecal impaction to the Ozempic label based on reports after the drug reached the market. These are uncommon, but they represent the more serious end of the gastrointestinal spectrum and tend to emerge with prolonged use rather than in the first few weeks.
Thyroid Cancer Risk: What the Warning Means
Ozempic carries the FDA’s most serious warning, a boxed warning, about thyroid C-cell tumors. In rodent studies, semaglutide caused dose-dependent and duration-dependent increases in thyroid cancers, including medullary thyroid carcinoma (MTC), at exposure levels comparable to what humans receive. Whether this translates to humans remains unknown. The biology of thyroid C-cells differs between rodents and people, and clinical studies haven’t been able to settle the question either way.
Because of this uncertainty, Ozempic is contraindicated if you have a personal or family history of MTC or a condition called Multiple Endocrine Neoplasia syndrome type 2. If you’re on the drug long-term, be aware of symptoms like a lump or mass in your neck, difficulty swallowing, shortness of breath, or persistent hoarseness. Routine screening with blood tests or thyroid ultrasound hasn’t been shown to reliably catch these tumors early in Ozempic users.
Pancreas and Gallbladder Effects
Acute pancreatitis has been a longstanding concern with drugs in this class. The reality is more nuanced than the warning label might suggest. A large propensity-matched analysis of GLP-1 receptor agonist users, including semaglutide, found that the risk of pancreatitis was essentially the same between users and non-users at six months. Over five years, those taking GLP-1 drugs actually had a statistically significant lower risk of pancreatitis than those who didn’t. That said, pancreatitis remains listed as a precaution, and severe abdominal pain that radiates to the back warrants immediate medical attention.
Gallbladder problems are a more concrete concern. Rapid weight loss from any cause increases the risk of gallstones, and the substantial weight loss Ozempic produces is no exception. Gallstones can lead to gallbladder inflammation, bile duct blockages, and sometimes surgery. This risk is tied to the pace and amount of weight loss rather than the drug’s direct mechanism.
Nutrient Deficiencies From Reduced Intake
One of the less-discussed long-term consequences of Ozempic is nutritional. The drug dramatically reduces appetite, and many users eat significantly less food for months or years. That caloric reduction often means falling short on key nutrients. In a study of roughly 461,000 participants, 13.6% developed vitamin D deficiency after 12 months on a GLP-1 drug. Iron deficiency affected 3.2%, B vitamin deficiency hit 2.6%, and 4% developed anemia from nutritional shortfalls.
A smaller study tracking the actual food intake of 69 GLP-1 users found the gaps were even wider: 72% consumed less than the recommended amount of calcium, 64% fell short on iron, and only 1.4% met vitamin D recommendations. Over months and years, these deficiencies can affect bone density, energy levels, immune function, and nerve health. A daily multivitamin and deliberate attention to protein and nutrient-dense foods can help offset this, but it requires conscious effort when your appetite is suppressed.
Muscle Loss During Weight Loss
When you lose a significant amount of weight on Ozempic, not all of it comes from fat. A portion comes from lean mass, meaning muscle and other non-fat tissue. This is true of any weight loss method, but it matters more with drugs that suppress appetite so effectively that people may eat far less protein than their body needs to maintain muscle. The ratio of muscle to fat loss becomes particularly important for older adults, where losing muscle can increase fall risk and reduce mobility. Resistance training and adequate protein intake (which can be challenging when your appetite is minimal) are the main strategies to preserve muscle during treatment.
Kidney Function
For people with type 2 diabetes, the news on kidney health is largely positive. A major clinical trial published in the New England Journal of Medicine found that semaglutide reduced major kidney disease events by 24% compared to placebo. Kidney function declined about a third more slowly in the semaglutide group, losing roughly 2.2 points of filtration capacity per year versus 3.4 in the placebo group. Rates of acute kidney failure were similar between the two groups (9.7% vs. 10.3%), suggesting semaglutide doesn’t increase that risk.
The kidney concern that does apply is indirect: the nausea, vomiting, and diarrhea Ozempic can cause may lead to dehydration, and dehydration is a well-known trigger for acute kidney injury. Staying hydrated matters more than usual when you’re on a drug that can cause persistent GI symptoms.
Vision Changes in People With Diabetes
If you have diabetic retinopathy, the existing damage to blood vessels in your eyes can temporarily worsen when blood sugar drops rapidly. Ozempic lowers blood sugar effectively, and that fast improvement can paradoxically stress already-damaged retinal blood vessels. This doesn’t mean semaglutide damages healthy eyes, but if you have a history of diabetic eye disease, your doctor will typically want to monitor your vision more closely during treatment, especially in the first year.
Mental Health and Suicidal Thoughts
Reports of suicidal thoughts in people taking GLP-1 drugs prompted an FDA investigation. The agency’s preliminary findings did not find evidence that these medications cause suicidal ideation. Reviews of clinical trial data, large outcome studies, and observational studies all failed to show an association. However, because the number of such events was small in both the treatment and control groups, the FDA hasn’t completely closed the book and continues to monitor the signal. For now, the evidence does not support a causal link, but if you notice significant mood changes while on the drug, it’s worth discussing with your prescriber.
Weight Regain After Stopping
One of the most predictable long-term patterns with Ozempic isn’t a side effect of taking it, but of stopping it. Clinical trial data consistently shows that people regain a significant portion of lost weight within a year of discontinuation. The appetite suppression, slower gastric emptying, and hormonal signals that drove weight loss reverse when the drug leaves your system. This means many people face a choice between indefinite use (with cumulative exposure to all the risks above) or accepting that much of the weight will return. Understanding this dynamic upfront helps set realistic expectations about how long treatment may need to last.