Mounjaro side effects: 10 common and long-term reactions you shouldn’t ignore

Mounjaro, one of the brand names for tirzepatide, is a drug that is beneficial for people with type 2 diabetes. This once-weekly injectable medicine can be paired with diet and exercise to help manage blood sugar levels. Also prescribed off-label for weight loss, the medicine has worked wonders for celebrities like Rosie O’Donnell, Whoopi Goldberg, and Amy Schumer. There are benefits, but it is best if you are wary of Mounjaro side effects too. Right from nausea to constipation, this anti-diabetes drug can have some adverse effects.

How does Mounjaro work?

“The weekly injection that comes in pre-filled pens mimics the activity of two natural hormones in the body,” says endocrinologist Dr Swati Tayal Goray. By mimicking the hormone glucagon-like peptide-1 (GLP-1), the medicine works as an appetite suppressant. This hormone is released after consuming food, and usually makes people feel fuller. Mounjaro also affects glucose-dependent insulinotropic polypeptide (GIP), a hormone that has an impact on metabolism. “Apart from suppressing hunger, these two hormones also regulate blood sugar,” says the expert.

The first dose of Mounjaro, which can be self-administered into the stomach, upper arm or thigh, is 2.5 mg. After using it for 4 weeks, the dose will be increased to 5 mg, according to the US Food and Drug Administration.

Is hair loss a side effect of Mounjaro?

You may wonder if Mounjaro and hair loss have a link. Well, it is not a direct side effect of Mounjaro, but some people may experience it. A study, published in The New England Journal of Medicine, showed that nearly 5 to 6 percent of participants taking tirzepatide (5 mg, 10 mg, and 15 mg) experienced hair loss. “Hair loss can be a temporary reaction to changes in the diet or weight loss, but not the medicine itself,” says Dr Goray.

What are the common Mounjaro side effects?

The common Mounjaro side effects are typically gastrointestinal in nature. Here are some of them:

1. Nausea

When you start using Mounjaro, it will slow down the emptying of the stomach. This delay can cause a feeling of fullness or unease, often resulting in nausea. “It is more common when the dose is first started or increased, and tends to improve over time as the body gets used to it,” says the expert.

2. Vomiting

In some people, especially during the early weeks of treatment, nausea may progress to vomiting. This happens because the stomach’s ability to contract and move food becomes slow. If vomiting is persistent or severe, it may require dose adjustment or medical attention.

3. Diarrhea

Diarrhea is one of the Mounjaro side effects. It can affect how the intestines absorb and process food. This may result in looser stools or more frequent bowel movements. “Diarrhea can range from mild to moderate, and usually decreases with continued use,” says Dr Goray.

4. Constipation

Conversely, some people experience reduced bowel movements or difficulty passing stools. Mounjaro can cause constipation due to slowed gastrointestinal movement and changes in appetite or diet as people eat less. Staying hydrated and increasing dietary fiber can help manage this.

5. Loss of appetite

Yes, one of the intended effects of Mounjaro is suppression of appetite. It works on hormones that signal satiety (fullness) to the brain, helping people eat less. “While beneficial for weight loss, the sudden reduction in appetite can be uncomfortable for some and may lead to nutrient deficiencies if not managed well,” says the expert.

6. Sulfur burps

These burps usually happen when bacteria in the gut produce hydrogen sulfide gas, which is naturally present in the digestive tract. But having huge amounts of this gas can lead to burps with an unpleasant smell. These burps may be one of the Mounjaro side effects. A study, published in the Journal of the Endocrine Society, showed that a user of Mounjaro had nausea, vomiting, indigestion and excessive burping for one day after taking the first dose of the medicine.

What are the Mounjaro long-term side effects?

While most people can tolerate Mounjaro well, there are a few potential long-term risks. Here are some of the Mounjaro side effects that can be experienced for long:

1. Stomach problems

If used for a long time, some people may experience persistent bloating, flatulence or discomfort in the abdomen. “This is likely due to the medication’s continued impact on slowing digestion and altering gut motility,” says the expert. Though not severe, it can affect the quality of life if these problems don’t stop.

2. Gallstones

Rapid weight loss, which is often seen with Mounjaro, can increase the risk of gallstone formation. “These stones are hard deposits that get formed in the gallbladder and can cause pain, indigestion, or in severe cases, require surgery,” says the expert. People with a history of gallbladder issues should check with their doctor before using the weight loss drug.

3. Pancreatitis

There is a rare but serious risk of pancreatitis (inflammation of the pancreas), which may lead to severe abdominal pain, nausea, and vomiting. Though uncommon, people with a history of pancreatitis should use the weight loss drug with caution.

4. Thyroid tumors

“Long-term use of medications like Mounjaro may increase the risk of medullary thyroid carcinoma (MTC), a rare type of thyroid cancer,” says the expert. However, this has not been proven in humans. As a precaution, people with a personal or family history of MTC should avoid using Mounjaro.

How to prevent Mounjaro side effects?

To prevent Mounjaro side effects, do the following:

• Always start with a low dose and then increase slowly, as prescribed by the doctor. “This is the most critical preventive step, as the body tolerates the medicine better when introduced gradually,” says the expert
• Avoid fatty or spicy foods while taking this weight loss drug, as they may upset your stomach.
• Drink water or electrolyte fluids in small sips throughout the day to avoid dehydration due to vomiting.
• Take it only under medical supervision and inform your doctor of any Mounjaro side effects immediately.

Mounjaro side effects like nausea and vomiting usually subside within a few days to weeks, as by that time the body adjusts to the drug. However, sometimes, the adverse effects can be experienced for a longer time. Make sure to consult a doctor regarding them.