What are the side effects of Wegovy?

You probably have certain hopes when you go on a GLP-1 medication like Wegovy, which is FDA-approved for weight management. Chief among them: losing weight. What you don’t wish for? Side effects like nausea, vomiting, or constipation. While these symptoms aren’t guaranteed when you’re on Wegovy (a brand name for the drug semaglutide), they can happen. The good news: There are things you can do to feel more comfortable. Here’s what you need to know about Wegovy side effects and how to handle them.

Why Wegovy side effects happen

To know why certain side effects happen, it’s important to first understand how GLP-1s like Wegovy work in the body. “These medications mimic naturally occurring proteins produced in the intestines that tell the brain when we’ve eaten,” explains Dr. Jaime Almandoz, M.D., a weight management specialist at UT Southwestern Medical Center in Dallas. Taking a GLP-1 medication lowers your appetite and cravings, makes you more full, and slows down the speed at which your intestines move and empty, he explains. Some people are more sensitive to these changes, which can contribute to the side effects.

Wegovy side effects are usually their most bothersome when you first start taking the medication or when you increase your dose. “The motto with medication like Wegovy is that you have to start low and go slow,” says Dr. Disha Narang, M.D., endocrinologist and director of obesity medicine at Endeavor Health in Skokie, IL. This is why Narang says she starts her patients at the lowest dose and keeps them there for one month to get their body acclimated before increasing the dosage.

Common side effects of Wegovy

“In practice, we find that about 20-30% of patients have side effects,” says Dr. Supriya Rao, M.D., a board-certified physician in internal medicine, gastroenterology, obesity medicine, and lifestyle medicine in Boston. This is similar to what’s reported in FDA data, which shows the most common side effect, nausea, happens in 44% of people on Wegovy (compared to 16% of people on a placebo). The next most common side effect, diarrhea, occurs in 30% of people on Wegovy (compared to 16% of people on a placebo). For a full list of side effects, visit the Wegovy website. Here are the most common, listed in order of how often they occur:

• Nausea
• Diarrhea
• Vomiting
• Constipation
• Abdominal pain
• Headache
• Fatigue
• Acid reflux

The reason so many are gastrointestinal in nature is because GLP-1 weight-loss medications like Wegovy slow down the speed at which food moves through your GI tract. This can make some people feel nauseous and bloated.

That said, you aren’t simply stuck with the discomfort. A healthy lifestyle can help manage these GI side effects. The WeightWatchers GLP-1 Program guides you to meet daily nutrition targets like fiber, protein, and water — which can help ease side effects including constipation and nausea — so you can lose weight and feel good at the same time. And for the most part, these common side effects of Wegovy are on the milder side. “Overall, patients may feel generally icky,” says Rao. But in some cases, these common side effects can be more severe. In randomized clinical trials, about 17% of patients dropped out due to side effects of semaglutide compared to 8% in the placebo group, most often due to GI problems.

Tips for managing nausea

Shifting your habits can help settle your stomach. Here’s how:

• Slow down: Eating too quickly can result in overeating, which can cause nausea. While on Wegovy for weight loss, you’ll likely need to eat smaller portions than before. Listen to your body. It may help to take a break halfway through your meal to check in with yourself to see if you’re still hungry.
  
  
• Reduce fat intake: High-fat or greasy foods slow digestion even more. “They can sit in your stomach and reflux back up,” says Almandoz. Reflux is often at the root of nausea, and it can also cause heartburn, burping, and vomiting — other potential side effects of Wegovy.
  
  
• Avoid big meals: “You can’t eat a huge meal while on Wegovy without feeling pretty sick,” says Rao. Smaller, more frequent meals will sit better in your stomach.
  
  
• Wait to eat: If you feel nauseous right now, “don’t feed the nausea,” says Almandoz. Adding more food may make your stomach feel like a rock, so he recommends waiting before eating again. Instead, try taking a walk to speed up digestion to help you feel better, sooner.
  
  
• Take an anti-nausea medication: Your provider may recommend taking an anti-nausea medication like Zofran (ondansetron) to help keep your stomach settled. This is something you’d only need to use when nausea hits. “Usually patients have symptoms one to two days after doing the injection,” says Rao. “On those days, some people really need anti-nausea medication to help them through it.” These meds can also come in handy during the first week or so after moving up to a higher dose, adds Narang.

Tips for managing constipation

A more sluggish GI system can lead to constipation, says Rao. These strategies can help get things moving again.

• Eat enough fiber: Aim for 25 grams (for women) to 38 grams (for men) of fiber per day from foods like fruits and vegetables, whole grains, legumes, nuts, and seeds. Fiber adds bulk and draws water into stool, leading to more comfortable bowel movements.
  
  
• Keep drinking: You might be avoiding drinking a lot of water when on a GLP-1 because you feel bloated, but hydration is important for a healthy GI system. How do you know if you’re drinking enough? Check out the color of your urine — it should be clear or pale yellow, like the shade of lemonade.
  
  
• Consider a stool softener: If fiber and water isn’t helping, you may want to try a stool softener, says Almandoz. These are available over-the-counter and produce a bowel movement within 12 to 72 hours.

Tips for managing diarrhea

Although some people on Wegovy have constipation, others can have diarrhea, which is when you have three or more loose, watery stools per day. Since one of the main concerns with diarrhea is dehydration, make sure that you’re consistently taking in fluids and fluid-rich foods like fruits and vegetables throughout the day. For relief, over-the-counter medications such as lmodium (loperamide) or Pepto-Bismol® (bismuth subsalicylate) can help.

Less common side effects of Wegovy

There are also some less common side effects — which occur in less than 10% of people who take Wegovy — that may happen due to the effect the medication has on your body. They include, in alphabetical order:

• Belching
• Bloating
• Dizziness
• Gas
• Indigestion
• Low blood sugar (for those who have type 2 diabetes)
• Mild allergic reaction
• Runny nose or sore throat
• Stomach flu
• Upset stomach

Experts aren’t sure why some of these occur, but others can be linked to the effect GLP-1 has on lowering blood glucose levels. This can result in symptoms like dizziness and light-headedness, especially in people with type 2 diabetes who are taking another medication that lowers glucose levels, like insulin.

Serious side effects of Wegovy

Some of the less common side effects are more serious than, say, bloating or heartburn. These include the following, in alphabetical order:

• Depression or suicidal thoughts and behavior: This has been reported in clinical trials and, as a result, those who have a history of suicidal attempts or active suicidal ideation should not start Wegovy. That said, medications causing depression isn’t something unique to GLP-1s, since many drugs can impact your brain’s chemistry. In fact, Wegovy may have less of an impact on depression than other medications: A recent study funded by the National Institutes of Health found that people using semaglutide had a 49-73% lower risk of suicidal ideation compared to taking other obesity or type 2 diabetes medications. If you have a history of depression or other mental health conditions, always discuss that with your provider before starting any new medication.
  
  
• Gallbladder problems: Gallstones developed in up to 1.6% of those on Wegovy in clinical trials, compared to 0.7% of those taking placebo. If gallstones block your bile ducts, you can have a gallbladder attack. Symptoms of a gallbladder attack include abdominal pain that lasts for hours, nausea and vomiting, fever, and jaundice.
  
  
• Pancreatitis: This is very rare but warrants a mention. Inflammation of the pancreas affected four adults taking Wegovy in clinical trials compared to one in a placebo group. Symptoms of pancreatitis include upper abdominal pain that may spread to your back, as well as fever, nausea, and vomiting.
  
  
• Low blood sugar: For adults with type 2 diabetes, one trial found that 6.2% of people on Wegovy experienced hypoglycemia compared to 2.5% of those on placebo. Symptoms of low blood sugar, which can be fatal if left untreated, include dizziness, lightheadedness, weakness, and irritability.
  
  
• Severe allergic reaction: Although severe allergic reactions, including anaphylaxis, have been reported in trials, a recent large cohort study concluded that anaphylaxis is rare on semaglutide. It happens only 3.6 times out of every 10,000 person-years — a measure of time used in scientific studies. That would be only 3.6 instances if 2,000 people used the medication for 5 years. Symptoms include swelling of your face, lips, tongue, or throat, as well as a severe rash.

If you experience any of the above symptoms or side effects, seek medical care immediately.

Long-term side effects of Wegovy

Side effects that can affect your health long-term are also possible, although they are rare and some have only been seen in animal trials. These include, in alphabetical order:

• Diabetic retinopathy: This can happen in people who have type 2 diabetes, possibly because of the dramatic impact Wegovy can have in improving glucose control. In one trial, the condition occurred in 4% of those on Wegovy who had type 2 diabetes and overweight compared to 2.7% of the placebo group.
  
  
• Kidney problems: This may mostly affect those with a history of kidney disease and may be more likely if you have severe nausea, vomiting, or diarrhea that causes low fluid levels in the body.
  
  
• Risk of thyroid cancer: Although this is listed on the prescription information, “the risk of medullary thyroid cancer was seen in phase 1 trials in animal studies. It’s never actually been seen in a human,” says Narang.