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Mounjaro long-term side effects: What to expect

What we know so far about the potential long-term side effects of Mounjaro
By | Jun. 5, 2025 Medically reviewed by Karen Berger, Pharm.D.
A GLP-1 pen: Mounjaro long-term side effects: What to expect

Key takeaways

  • Mounjaro isn’t associated with many long-term side effects, but that may be due to limited long-term research.

  • It is important to discuss the long-term risks and benefits of Mounjaro treatment with your healthcare provider, especially if you have other health conditions or concerns.

  • Many diabetes drugs carry a risk of long-term adverse side effects.

In this article:

Mounjaro (tirzepatide) is a brand name glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist manufactured by Lilly. It’s approved by the Food and Drug Administration to treat Type 2 diabetes and may be prescribed off-label for weight loss. It’s injected under the skin once per week to help control blood sugar levels. The most common side effects of Mounjaro typically go away after several weeks. The long-term side effects of Mounjaro haven’t been well documented but may include an increased risk of gallstones. Animal studies have found an increased risk of thyroid cancer, but it is not known if this risk applies to humans. 

What are common Mounjaro side effects?

Mounjaro side effects typically affect the gastrointestinal (GI) system and may include:

  • Decreased appetite
  • Nausea
  • Vomiting
  • Diarrhea 
  • Constipation
  • Indigestion, stomach pain, or burping
  • Gastroesophageal reflux disease (GERD) 
  • Injection site reactions

Serious side effects of Mounjaro

Mounjaro has been linked to serious side effects that require immediate medical attention, including:

  • Pancreatitis (inflammation of the pancreas)
  • Hypoglycemia (low blood sugar)
  • Kidney problems
  • Gallbladder problems
  • Worsening diabetic retinopathy
  • Severe allergic reactions

Are there any long-term side effects of Mounjaro?

The long-term adverse side effects of Mounjaro and other GLP-1 receptor agonists remain largely unknown. However, studies point to a few concerns.

Mounjaro comes with a boxed warning (also called a black box warning) for thyroid cancer because GLP-1 agonists caused thyroid tumors in lab mice. Studies examining the link between thyroid cancer and GLP-1 medications in people have produced mixed results:

  • A 2023 study found an increased risk of thyroid cancer in people who had used GLP-1 receptor agonists (specifically exenatide, liraglutide, or dulaglutide) for one to three years. 
  • Another 2023 study found no increased risk of thyroid or pancreatic cancer in people who had taken semaglutide. 
  • A 2025 study found no increased risk of thyroid cancer in people who had taken tirzepatide (the active ingredient in Mounjaro and in Zepbound) for six to 18 months. 

In addition, people who had taken GLP-1 agonists for at least 12 weeks were found to be at an increased risk for gallstones (cholelithiasis). 

On a more positive note, one clinical trial found that Mounjaro lowered the risk of heart failure among participants who had taken it for two years. Findings from the same study suggest that Mounjaro may also reduce inflammation throughout the body.

How to avoid Mounjaro side effects

For many people, Mounjaro side effects go away with consistent use. “The side effects tend to kick in during the first month but almost always disappear by month three,” says Megan Horsham, MD, a medical weight loss doctor at The Sanctuary Wellness Institute who prescribes GLP-1 receptor agonists like Mounjaro. Some people may experience side effects when increasing the dose. 

Until then, try these tips to ease the gastrointestinal discomfort commonly associated with Mounjaro:

  • Eat smaller meals throughout the day.
  • Eat slowly.
  • Sip water or tea, especially if vomiting or constipated.
  • Eat foods that are easy to digest, such as toast, applesauce, bananas, rice, crackers, potatoes, broth-based soups, and chicken.
  • Avoid spicy, greasy, or high-fat foods.
  • Combat nausea by nibbling on gingersnaps or drinking ginger tea.
  • Use over-the-counter medications to control constipation, diarrhea, or heartburn. You can ask your healthcare provider or pharmacist for a recommendation.

Your healthcare provider should start you on a low dose of Mounjaro and gradually increase it over time until you reach an effective and tolerable dose. “[Titration] gives your system time to adapt to the medication,” says Arnold Breitbart, head plastic surgeon at the New York Liposuction Center.

Talk to your prescribing physician right away if you start to struggle with side effects. “I’ve had patients go from nearly giving up on Mounjaro to tolerating it beautifully with just a little support,” says Dr. Breitbart. He recommends day-to-day strategies like those listed above, but he says some patients benefit from a short-term prescription for anti-nausea medications “to get them over the hump.” 

Dr. Horsham shares another tip: “Injecting the medication in your arm or thigh may cause less nausea than injecting it into your stomach. It appears the absorption rate might be slightly slower here, which could lessen potential effects.” 

Don’t change the dose or quit taking Mounjaro without seeking medical advice, as skipping or delaying a dose of Mounjaro may lead to withdrawal symptoms like nausea, vomiting, constipation, irritability, and increased blood sugar levels. 

Mounjaro alternatives

If you find Mounjaro side effects intolerable, you’re not alone. In one study, 7% of participants had to withdraw due to the side effects of Mounjaro. 

Popular Mounjaro alternatives include other GLP-1 receptor agonists like semaglutide (Ozempic, Wegovy, and Rybelsus), exenatide (Byetta), dulaglutide (Trulicity), and liraglutide (Victoza and Saxenda). Unfortunately, these tend to produce the same side effects as Mounjaro. 

“Nausea, vomiting, and gastrointestinal discomfort are common across all these medications,” Dr. Breitbart says. “Some patients have reported more pronounced appetite suppression and changes in taste [with Mounjaro], but it’s mostly anecdotal.” 

If you’re concerned about the short- and long-term effects of Mounjaro, talk to a healthcare professional about other diabetes or weight management medications. Although stomach upset is a common side effect in other diabetes drugs like metformin and sulfonylureas, your body may react differently to each type of medication. 

Below are some Mounjaro alternatives and their common and long-term side effects. 

Metformin

Metformin is the most widely prescribed diabetes medication and is usually healthcare providers’ first-line treatment. It’s the only drug in the biguanide class. 

Possible side effects of metformin include upset stomach, nausea or vomiting, diarrhea, gas, headache, and low energy. Vitamin B12 deficiency is a long-term side effect of metformin. 

DPP-4 Inhibitors

Dipeptidyl peptidase-4 (DPP-4) inhibitors include Januvia (sitagliptin) and Onglyza (saxagliptin), among others. Common side effects of Januvia include headache, upper respiratory tract infection, sore throat, and a stuffy or runny nose. 

In 2015, the Food and Drug Administration warned consumers about debilitating joint pain as a result of DPP-4 inhibitors. The pain could start at any time, even years after starting a DPP-4 inhibitor. There have been cases of heart and kidney problems associated with DPP-4’s, so tell your healthcare provider if you have heart or kidney problems or are considered high risk for heart or kidney problems. 

Thiazolidinediones

Also called glitazones or TZDs, thiazolidinediones include the Type 2 diabetes medication Actos (pioglitazone). Pioglitazone is available alone and as part of various combination medications that contain more than one active ingredient. Common side effects of pioglitazone include fluid retention, headache, upper respiratory tract infection, sore throat, stuffy nose, and muscle pain.

Researchers have found that the risk of serious pneumonia or a lower respiratory tract infection is higher when thiazolidinediones are taken long-term. And because thiazolidinediones cause fluid retention, their use may increase the risk of edema and congestive heart failure. Other side effects associated with their long-term use include fractures, bladder cancer, liver toxicity, increased ovulation, and possible birth defects.

Sulfonylureas

The sulfonylureas drug class includes Amaryl (glimepiride), Glucotrol (glipizide), and Glynase (glyburide). Common glimepiride side effects include headache, dizziness, weakness, and hypoglycemia (low blood sugar levels). 

One potential side effect of long-term sulfonylurea use is a decrease in insulin secretion, which may make your diabetes more difficult to manage in the future. 

Sodium-glucose cotransporter 2 (SGLT2) inhibitors

SGLT2 inhibitors, such as Jardiance (empagliflozin) and Farxiga (dapagliflozin), are commonly prescribed for Type 2 diabetes. These drugs have other uses, too. For example, Jardiance can be used in people with heart disease, heart failure, or kidney disease. Common side effects include urinary tract and genital yeast infections. Long-term side effects may include an increased risk of lower limb amputation. Additionally, other serious side effects may occur, such as serious UTIs or necrotizing fasciitis (a rare but serious infection that occurs between the anus and genitals).

Other antidiabetics

Your healthcare provider may also prescribe insulin, meglitinides, or other medications (including combination drugs that contain more than one active ingredient) to control Type 2 diabetes and weight. The risk of short- and long-term side effects should be weighed against the health benefits provided by the medication. 

GLP-1 receptor agonists like Mounjaro aren’t associated with as many long-term side effects as other antidiabetic medications, but that may be because there has been limited long-term research into this class of drugs. With more studies, we may learn about additional long-term concerns. Until then, your healthcare provider can help you decide if Mounjaro is safe for you.