Ozempic’s most common side effects are gastrointestinal: nausea, vomiting, diarrhea, abdominal pain, and constipation, each affecting at least 5% of users in clinical trials. Most of these symptoms are worst during the first weeks of treatment and tend to ease as your body adjusts, but some people experience more serious complications that deserve attention.
Nausea, Vomiting, and Other Digestive Issues
Stomach-related problems are by far the most frequently reported side effects. In trials comparing the two main doses, gastrointestinal symptoms occurred in about 31% of people on the lower dose and 34% on the higher dose. Nausea is the single most common complaint, often appearing within the first few days of a new dose and gradually fading over several weeks.
For most people, these symptoms are uncomfortable but manageable. Severe gastrointestinal reactions are uncommon, occurring in less than 1% of users. Still, roughly 3% to 4% of people in clinical trials stopped taking Ozempic specifically because of digestive side effects, compared to less than half a percent of those on placebo. Eating smaller meals, avoiding high-fat foods, and staying hydrated can help reduce the intensity of nausea and vomiting during dose increases.
Ozempic is started at a low dose and increased gradually over several months to give your digestive system time to adapt. Each dose level is typically held for at least four weeks before moving up. Skipping this gradual approach or increasing too quickly tends to make nausea and vomiting significantly worse.
Stomach Paralysis and Severe Delayed Digestion
Ozempic works partly by slowing the rate at which food leaves your stomach, which helps control blood sugar and reduces appetite. In some people, this effect becomes extreme enough to cause gastroparesis, a condition where the stomach essentially stops contracting and can no longer push food through the digestive tract normally.
Recent research suggests that as many as 1 in 20 new users who are obese or have diabetes develop stomach paralysis. That risk is roughly four times higher than with non-GLP-1 weight loss medications. Symptoms include persistent nausea, vomiting undigested food hours after eating, severe bloating, and a feeling of fullness after just a few bites. If you notice these symptoms worsening rather than improving over time, it’s worth raising them with your prescriber, since gastroparesis can sometimes require stopping the medication.
Thyroid Tumor Warning
Ozempic carries the FDA’s most serious label warning, a boxed warning, related to thyroid cancer risk. In animal studies, semaglutide caused thyroid C-cell tumors at doses similar to those used in humans. Whether this translates to an actual risk in people remains unknown.
Because of this uncertainty, Ozempic is not prescribed to anyone with a personal or family history of medullary thyroid carcinoma or a condition called Multiple Endocrine Neoplasia syndrome type 2. Signs to watch for include a lump or mass in the neck, difficulty swallowing, shortness of breath, or persistent hoarseness that doesn’t go away. Routine thyroid screening with blood tests or ultrasound hasn’t been shown to reliably catch problems early in people on the medication.
Pancreatitis and Gallbladder Problems
Acute pancreatitis, an inflammation of the pancreas that causes severe upper abdominal pain, has been reported in a small number of Ozempic users. In one weight loss trial, 3 out of 1,306 participants on semaglutide developed pancreatitis compared to zero out of 655 on placebo. A large meta-analysis of semaglutide trials ultimately found no statistically significant increase in pancreatitis risk overall, but the numbers are small enough that vigilance is still warranted.
Gallbladder issues are a related concern. Ozempic slows the movement of bile, which can lead to the formation of sludge and gallstones, particularly during rapid weight loss. Warning signs include discomfort or a feeling of fullness in the upper right side of your abdomen, persistent pale stools, and ongoing nausea that doesn’t respond to the usual strategies. People losing weight very quickly on Ozempic may benefit from gallbladder imaging to catch stones before they cause complications.
Low Blood Sugar With Other Diabetes Medications
Ozempic on its own rarely causes dangerously low blood sugar. The risk changes substantially, however, when it’s combined with insulin or medications that stimulate insulin release, such as sulfonylureas. Using semaglutide alongside insulin increases the chance of hypoglycemia, and your prescriber will often lower the dose of your other diabetes medication when adding Ozempic to prevent blood sugar from dropping too low.
Symptoms of low blood sugar include shakiness, sweating, confusion, dizziness, and feeling unusually hungry. If you’re on combination therapy, more frequent blood sugar monitoring is important, especially during the early weeks and whenever your Ozempic dose is increased.
Vision Changes in People With Diabetes
A secondary analysis of the SUSTAIN-6 clinical trial found a significantly increased risk of diabetic retinopathy complications in people taking Ozempic. This finding was somewhat unexpected and appears to be linked to how rapidly blood sugar levels drop rather than a direct toxic effect on the eyes. People who already have diabetic retinopathy or poorly controlled blood sugar seem to be at highest risk.
If you have a history of diabetic eye disease, your eye doctor should be aware that you’re starting Ozempic. Blurred vision and other visual changes during the first months of treatment are worth getting checked promptly.
Facial Changes and Muscle Loss
The widely discussed “Ozempic face” isn’t a pharmacological side effect of the drug itself. It’s a consequence of rapid weight loss. When you lose weight quickly, you lose subcutaneous fat from your face and neck, which is the layer just beneath the skin that gives your face its fullness and structure. The result can be sunken cheeks, new wrinkles, and sagging skin along the jawline and neck.
Rapid weight loss also reduces levels of collagen and elastin, two proteins that keep skin firm and stretchy. This makes it harder for skin to “snap back” after volume is lost, particularly in people over 40. Losing weight at a slower, steadier pace, maintaining adequate protein intake, and incorporating resistance exercise can help preserve both facial fullness and lean muscle mass.
Mood Changes and Suicidal Thoughts
Reports of depression and suicidal thoughts in people taking GLP-1 medications prompted an FDA investigation. After reviewing clinical trials, large observational studies, and individual case reports, the agency’s preliminary evaluation found no evidence that these medications cause suicidal thoughts or actions. The reports were often complicated by other factors, including pre-existing mental health conditions, making it difficult to isolate any drug effect.
The FDA has not closed the investigation entirely. Because the absolute numbers of suicidal events in clinical trials were small in both treatment and placebo groups, the agency says it cannot definitively rule out a small risk and is continuing to analyze postmarketing data. If you notice significant mood changes after starting Ozempic, bringing them up with your prescriber is reasonable regardless of whether the drug is the cause.