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The 5 most common Ozempic and Mounjaro side effects

1 min Read

Remember when the only way to address obesity centered around calorie restriction and increased physical activity? Yup, we do too. And while “eat less, move more” can be a part of a weight loss strategy, some people need additional help. For those individuals, GLP-1s have completely changed the face of obesity treatments. Now, there’s a […]

Ozempic and Mounjaro side effects

Remember when the only way to address obesity centered around calorie restriction and increased physical activity? Yup, we do too. And while “eat less, move more” can be a part of a weight loss strategy, some people need additional help. For those individuals, GLP-1s have completely changed the face of obesity treatments. Now, there’s a whole new set of tools at our fingertips, and they’ve made a world of difference for many people struggling with obesity. But like all medications, GLP-1s, like Ozempic and Mounjaro, have their own set of potential side effects.

Ozempic and Mounjaro side effects

Despite their popularity, it’s important to remember that Ozempic, Mounjaro, and all other prescription meds are powerful drugs, requiring close monitoring by a doctor. Up to 50% of  GLP-1 users may experience some form of side effects during treatment. Fortunately, the majority of these are mild and tend to resolve with time.

How Ozempic and Mounjaro work

To understand side effects, we first need to understand how these medications operate. 

Ozempic, Mounjaro, and other GLP-1s stimulate the release of insulin and suppress glucagon. (Sounds complicated, we know). They’ve shown promise in not only promoting weight loss but also addressing the metabolic realities associated with obesity. That’s much needed.

But here’s what’s most important: One of the primary reasons that Ozempic and Mounjaro are effective is that they slow gastric emptying. This results in people feeling more satiated with smaller amounts of food. 

Unfortunately, that same increase in fullness – which directly leads to weight loss – can also lead to side effects, like nausea. (Cruel irony, right)

In addition, as we mentioned, GLP-1s can lead to increased insulin secretion from the pancreas. While this is generally beneficial for managing blood sugar levels, it can pose challenges, especially for people already on diabetes medications. In some people, increased insulin secretion may lead to hypoglycemia or abnormally low blood sugar. This is why careful monitoring is so important, particularly in patients with pre-existing diabetes, to prevent and manage potential episodes of low blood sugar.

Ozempic and Mounjaro side effects: Which are most common?

So what side effects are most commonly associated with GLP-1s like Ozempic and Mounjaro?

1: Nausea

Yup, this is the biggie. As we already explained, the slowing of gastric emptying may lead to experiencing extreme fullness that triggers nausea. Along the same lines,vomiting is also a potential (but less common) side effect. While these symptoms can certainly be uncomfortable, they tend to resolve over time as the body adjusts to the medication.

What you can do: You can try addressing nausea by eating smaller, more frequent meals throughout the day: try cutting your portions in half. You can also try eating until you feel 70% full, then waiting an hour to see if you’re still hungry for more. 

Nausea on Ozempic or Mounjaro might also be because the meds cause your pancreas to secrete more insulin. In this case, limiting your intake of carbs and sugars may help.  

Lastly, your clinician may recommend temporarily lowering your dose to mitigate these side effects. If the nausea is severe or persistent, your doctor may also recommend anti-nausea medication. 

2: Constipation

Ah, those tummy troubles. Ozempic and Mounjaro, by design, slow gastric emptying, affecting traffic in the gut and potentially leading to constipation. 

What you can do: To manage this side effect, you can adopt a few simple changes. Consuming high-fiber carbohydrates (such as green vegetables), staying well-hydrated, and incorporating daily walking into your routine can help stimulate bowel movements. These measures aim to counteract the impact on gut transit time, promoting regularity and minimizing the discomfort associated with the side effect of constipation.

3: Fatigue

Fatigue is another common Ozempic and Mounjaro side effect. It can be the result of various factors, including dehydration, low blood sugar levels, or excess insulin secretion. Similarly, on Ozempic or Mounjaro, you may experience lightheadedness. 

What you can do: Maintaining adequate hydration, closely monitoring blood sugar levels, and eating salty foods can help alleviate these discomforts.

4. Headache

Headaches are another potential side effect of Ozempic and Mounjaro. They are also often linked to dehydration, low blood sugar, or excess insulin secretion. 

What you can do: People using Ozempic or Mounjaro should prioritize staying well-hydrated, consuming regular and balanced meals, and monitoring their blood sugar levels consistently (if that is something your doctor recommends). 

5. Injection Site Reactions

As you probably know, Ozempic and Mounjaro are administered through injections, and injection site reactions are another possible side effect. This may result in mild pain, swelling, redness, or bruising that can persist for a few days or up to a week. 

What you can do: Rotating injection sites and proper injection techniques can help minimize the side effect. If it’s persistent or severe, it’s important to seek guidance from your healthcare provider.

Some less common Mounjaro and Ozempic side effects

  • Fast heart rate. This can occur due to the impact of Ozempic or Mounjaro on your heart muscle. It may also be related to these medications’ positive impact on cardiovascular disease. Talk to your doctor if you experience heart palpitations or a persistently elevated heart rate over 100. 
  • Gallbladder issues. This side effect is not well understood. But here’s what we know. The gallbladder may empty more slowly while on these medications, or the composition of bile produced by the gallbladder may change. Rapid weight loss also comes with an increased risk of stone formation. If you have a family history of gallbladder issues, are at risk of developing them, or have abdominal pain, talk to your doctor. 
  • Hair loss. Watching large chunks of hair fall out of your head can be really scary. But it actually can happen with any kind of weight loss. It occurs because losing weight leads more hair follicles to shift to a resting state (known as telogen effluvium). One of the best ways to remedy this side effect is to eat more protein. But it’s important to get your labs checked by your doctor, to rule out other causes, like anemia, a vitamin deficiency, or a slow thyroid. 

Keep all of this top of mind when you’re taking Ozempic, Mounjaro, or any similar medication. If any side effects don’t resolve, or you develop a rash, itching, or anything else that feels severe, it’s important to talk to your doctor immediately. They can help adjust your medication and weight loss regimen to help ensure you safely achieve your goals. 

Note: Ozempic is not FDA approved to treat obesity or for weight loss.


Linda Anegawa, MD is Noom’s Chief Medical Officer where she brings decades of experience in academic primary care, bariatrics, advisory board service, and leadership in digital health. She is certified by the American Board of Obesity Medicine and the National Board of Physicians and Surgeons, and is a Fellow of the American College of Physicians.