What Is the Dark Side of Semaglutide?

Bad reactions to semaglutide can occur, and some users have experienced severe and life-altering side effects after taking the drug. Some of the drug’s potential complications are included in U.S. Food & Drug Administration (FDA) labels, but others aren’t.

Bad side effects of semaglutide may include:

Listed semaglutide side effects

• Acute kidney injury: An acute kidney injury (AKI) is the sudden occurrence of kidney damage or kidney failure. The condition, which can be fatal, causes waste to build and can affect other body systems.
• Acute gallbladder disease: Semaglutide can cause gallstones (cholelithiasis) and gallbladder inflammation (cholecystitis).
• Diabetic retinopathy: Patients with type 2 diabetes are already at risk for diabetic retinopathy (DR). Semaglutide can increase the chances of developing this complication. DR occurs when excess blood sugar creates blockages in blood vessels in the eyes, leading to vision problems and vision loss.
• Multiple endocrine neoplasia, type 2 (MEN 2): Drugs containing semaglutide carry a “boxed warning” for MEN 2. This warning is the most serious type issued by the FDA. MEN 2 is a rare genetic condition that causes tumors to grow in the thyroid, parathyroid and adrenal glands, lips, mouth, eyes and digestive tract. People with a personal or family history of MEN 2 are among those who shouldn’t take semaglutide.
• Pancreatitis: Inflammation in the pancreas, or pancreatitis, can cause belly pain, upset stomach, vomiting and weight loss. When not treated, pancreatitis can lead to severe complications that include infection, kidney failure and pancreatic cancer.
• Pulmonary aspiration: Pulmonary aspiration occurs when a patient inhales food or liquid from the stomach into the lungs. Because semaglutide causes delayed gastric emptying, patients undergoing sedation during surgery are at an increased risk for pulmonary aspiration. The American Society of Anesthesiologists recommends temporarily halting the use of GLP-1 medications before planned procedures.
• Thyroid C-cell tumors: Semaglutide’s boxed warning also states that the drug has caused thyroid C-cell tumors in rodents. This risk includes medullary thyroid carcinoma (MTC), an aggressive type of thyroid cancer. People with a personal or family medical history of MTC shouldn’t take semaglutide.

Ozempic, the first semaglutide drug, was FDA approved in 2017.  Some of semaglutide’s on-label side effects didn’t get added until after the drug had been on the market for several years. For example, warnings about pulmonary aspiration weren’t included until November 2024.

Unlisted side effects

• Vision changes: Studies link semaglutide to an increased risk of non-arteritic anterior ischemic optic neuropathy (NAION). NAION causes a lack of blood flow to the eye, damaging the optic nerve. It can cause vision loss and blindness. NAION is sometimes called eye stroke or eye rotting.
• Deep vein thrombosis: Deep vein thrombosis (DVT) is the formation of blood clots in the body’s deep veins, usually in the legs. A clot that breaks loose can travel into the lungs, blocking blood flow and causing a potentially fatal pulmonary embolism. Research finds that semaglutide may increase the risk of clots in the deep veins by more than 250%.
• Gastroenteritis: Semaglutide can cause gastroenteritis (stomach inflammation). Symptoms include abdominal pain, diarrhea, nausea, vomiting, fever and chills. FDA labels for Wegovy and Rybelsus warn of “severe gastrointestinal adverse reactions” but don’t mention gastroenteritis. Wegovy and Rybelsus didn’t carry these warnings until November 2024 and December 2024, respectively. Ozempic’s warnings still don’t include stomach problems.
• Gastroparesis: Gastroparesis, or stomach paralysis, is a permanent condition that slows down the muscles and nerves in the stomach. It can cause pain, indigestion, bloating, constipation, nausea, vomiting, malnutrition and dehydration. It can also lead to a blockage resulting from a bezoar, which is a collection of material that hasn’t properly digested. Semaglutide labels warn about delayed gastric emptying. However, labels don’t explicitly list gastroparesis as a side effect.
• Intestinal blockage: Warning labels for semaglutide drugs Ozempic and Wegovy don’t warn about intestinal blockage — though users have reported the condition in post-marketing experiences.

If you experience on- or off-label side effects of semaglutide, reach out to your healthcare provider. Don’t discontinue the use of your medication without first consulting a doctor.

If you or someone you love developed a medical problem after taking semaglutide, you may be eligible for a semaglutide lawsuit. Legal action against Novo Nordisk alleges that the pharmaceutical company failed to warn patients about dangerous side effects.

Semaglutide can be expensive. In 2024, Ozempic and Wegovy had price tags of right at or over $1,000 per month. These high costs can limit which patients have access to drugs needed to treat type 2 diabetes or manage obesity.

Research shows that most patients on semaglutide pay through commercial insurance. Medicaid, Medicare Part D and cash payments are much less common.

Semaglutide controversies include supply chain issues. Of the three semaglutide drugs on the market, only Wegovy is FDA-approved to promote weight loss. Ozempic and Rybelsus are approved only for the treatment of type 2 diabetes. Off-label use of Ozempic and Rybelsus for weight management has led to shortages of these drugs. Semaglutide injections were on the FDA’s Drug Shortage List from August 2022 through February 2025.

Studies found that more than a third of people taking Ozempic in 2023 had no history of type 2 diabetes. In some markets, off-label use of semaglutide has more than doubled in recent years. This increase has caused some patients who need semaglutide for disease management to have difficulty obtaining the drug. Novo Nordisk says fulfilling the demand could take years.

Understanding compounded semaglutide

When a medication is on the FDA Drug Shortage List, compounding pharmacies are given temporary authorization to produce versions of the drug to keep up with demand. Semaglutide’s popularity and presence on the shortage list for several years gave rise to compounded versions. Compounding is the practice of combining or mixing ingredients to make a medication. Compounded drugs aren’t FDA-approved.

In July 2024, the FDA issued an alert about compounded semaglutide. The communication warned patients, healthcare providers and compounders about reports of adverse events, overdoses and drug errors involving injectable compounded semaglutide.

According to the FDA, compounded semaglutide is dangerous because varying concentrations, containers and packaging can lead to dosage errors. Compounded medications don’t undergo FDA premarket review for safety, quality or effectiveness. Motley Rice is not reviewing cases involving compounded semaglutide medications at this time.

There may be a dark side to semaglutide that includes high costs, lack of accessibility and the possibility of health complications. Dangerous potential side effects of semaglutide include:

• Kidney and gallbladder problems
• Pancreatitis
• Severe gastrointestinal issues
• Vision loss

You should consult a doctor before starting any medication. When weighing the drawbacks and dangers of semaglutide, you and your healthcare provider should consider whether:

• You have a personal or family medical history that prevents you from taking semaglutide
• The drug is FDA-approved or a compounded version
• The drug’s cost and supply chain issues will limit your access
• The drug is needed to treat diabetes, promote weight loss or do a combination of the two
• The medication is prescribed for an on- or off-label use, or both

You may be eligible to take legal action against Novo Nordisk if you have wrongfully suffered after using semaglutide. You may qualify to seek compensation for any medical expenses and/or lost wages you believe to be connected to your use of semaglutide.

We’ve helped thousands of injured patients with medical drug lawsuits. Motley Rice attorneys are currently reviewing claims related to diabetes lawsuits, semaglutide and other GLP-1 RA medications. These semaglutide and other GLP-1 RA drugs include:

• Ozempic
• Rybelsus
• Wegovy
• Mounjaro®
• Trulicity®
• Zepbound®

Don’t stop taking prescribed medication without first consulting your doctor. Discontinuing a prescribed medication without your doctor’s advice can result in injury or death. Mounjaro, Ozempic, Rybelsus, Trulicity, Wegovy and Zepbound remain approved by the U.S. Food and Drug Administration.