This article describes possible side effects of Mounjaro. You can explore this overview article to learn more about Mounjaro, including the drug’s uses, side effects, ways to save on cost, and more.
Mounjaro is a brand-name medication that comes as an injection that’s given under your skin. It isn’t available in a generic version. This article describes possible side effects of Mounjaro.
Boxed warning: Risk of thyroid tumors and thyroid cancer
Mounjaro has a boxed warning for the risk of thyroid tumors and thyroid cancer. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).
For details, see the “Side effects of Mounjaro in detail” section below.
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More common side effects of Mounjaro
Mounjaro injection may cause mild or serious side effects. Below are some of the more common side effects of this medication.
Commonly reported side effects of Mounjaro injection include:
- decreased appetite
- constipation*
- diarrhea
- indigestion
- nausea and vomiting*
- stomach pain
* To learn more about this side effect, see the “Side effects of Mounjaro in detail” section below.
Mild side effects of Mounjaro
Mounjaro may cause certain mild side effects. Most often, mild side effects are temporary and can be easily managed. Tell your doctor or pharmacist if you have side effects that don’t go away or become bothersome.
Mild side effects of Mounjaro injection that occurred in studies include:
- decreased appetite
- constipation*
- diarrhea
- indigestion
- injection site reactions
- nausea and vomiting*
- stomach pain
- mild allergic reaction*
* To learn more about this side effect, see the “Side effects of Mounjaro in detail” section below.
Mounjaro injection may cause more mild side effects than those listed above. For details, see the drug’s prescribing information.
Serious side effects of Mounjaro
Mounjaro may cause certain serious side effects, but they’re rare. If you have any serious side effects from Mounjaro injection, call your doctor right away. But if you think you’re having a medical emergency or your side effects feel life threatening, take immediate action. Call 911 or a local emergency number, or go to the nearest emergency room.
After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Visit MedWatch’s website if you’d like to notify the FDA about a side effect you’ve had with Mounjaro.
Serious side effects of Mounjaro injection that occurred in studies include:
- pancreatitis (inflammation of the pancreas)
- gallbladder problems
- severe digestive side effects, such as diarrhea, nausea, or vomiting, which may lead to dehydration and kidney problems
- hypoglycemia (low blood sugar)
- risk of thyroid tumors and thyroid cancer*
- severe allergic reaction†
* Mounjaro injection has a boxed warning for this side effect. A boxed warning is the most serious warning from the FDA. To learn more, see the “Side effects of Mounjaro in detail” section below.
† To learn more about this side effect, see the “Side effects of Mounjaro in detail” section below.
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Get free cardCommon questions about side effects of Mounjaro
Here are answers to some common questions about side effects of Mounjaro injection. If you have other questions, talk with your doctor or pharmacist.
How long do side effects of Mounjaro usually last?
It depends on several factors, including the specific side effect, how you respond to the drug, and how your doctor prescribes Mounjaro injection. Most mild side effects usually go away in a few days or weeks.
The most common side effects of Mounjaro injection include digestive side effects, such as diarrhea, nausea, and vomiting. In studies, these side effects happened most often when the dose of Mounjaro was increased after starting the drug. These side effects usually get better over time.
Talk with your doctor or pharmacist if you have questions about side effects of Mounjaro injection or you have side effects that don’t go away or get worse over time.
Can Mounjaro cause hair loss?
Hair loss wasn’t seen in studies of Mounjaro injection. But hair loss was a common side effect in studies of Zepbound. Both Mounjaro and Zepbound contain the same active ingredient, tirzepatide. (An active ingredient is what makes a medication work).
Even though Mounjaro and Zepbound have the same active ingredient, they’re approved for different uses. Mounjaro is approved to help manage blood sugar levels in adults with type 2 diabetes. Zepbound is approved to help manage weight in adults with obesity or adults with overweight who also have a weight-related condition, such as type 2 diabetes.
In studies of Zepbound, hair loss was associated with losing weight. Because Mounjaro and Zepbound have the same active ingredient, side effects are likely to be similar overall. Any hair loss that occurs with Mounjaro may depend on whether you lose weight with the medication.
Having diabetes can also sometimes lead to hair loss. See this article for more details about how diabetes can affect hair loss and how to manage it.
If you have questions about hair loss with Mounjaro, talk with your doctor.
Can Mounjaro cause weight loss?
Yes, Mounjaro can cause weight loss. In studies, some people with type 2 diabetes who took Mounjaro had a decrease in body weight. One way Mounjaro injection works is by slowing how quickly your stomach empties. This may help you feel fuller for longer after you eat. Mounjaro injection can also cause decreased appetite or nausea, which could lead to weight loss.
But Mounjaro is not approved for weight loss. It’s approved to help manage blood sugar levels in adults with type 2 diabetes.
Still, doctors sometimes prescribe Mounjaro for off-label use. With off-label use, doctors prescribe a drug for a purpose other than what it’s approved for. However, Mounjaro injection likely won’t be covered by insurance for off-label uses, including weight loss. Insurance plans usually only cover Mounjaro for people who meet certain criteria.
There are other drugs similar to Mounjaro that are specifically approved for weight loss. Mounjaro contains tirzepatide as its active ingredient. (An active ingredient is what makes a medication work). Another drug, Zepbound, also contains tirzepatide. But Zepbound is approved to help manage weight in adults with obesity or adults with overweight who also have a weight-related condition, such as type 2 diabetes.
Talk with your doctor if you have questions about weight loss with Mounjaro or Zepbound.
Does Mounjaro cause long-term side effects?
In some cases, Mounjaro injection may cause long-term side effects. These can occur if you take the drug for a long time or may last for a while after you’ve stopped taking the drug. But long-term side effects with Mounjaro injection are rare.
If they occur, some serious side effects, such as the risk of gallbladder problems, thyroid tumors, and thyroid cancer,† could affect your health long term. If you have questions about these possible side effects, talk with your doctor. They can discuss the risk of these side effects with you or help you manage any side effects you may have while using Mounjaro.
Talk with your doctor if you have more questions about possible long-term side effects of Mounjaro injection.
† Mounjaro injection has a boxed warning for this side effect. A boxed warning is the most serious warning from the FDA. To learn more, see the “Side effects of Mounjaro in detail” section below.
Side effects of Mounjaro in detail
Below you’ll find details on some of the side effects of Mounjaro injection.
Risk of thyroid tumors and thyroid cancer
Mounjaro injection has a boxed warning about the risk of possible thyroid tumors and thyroid cancer. A boxed warning is the most serious warning from the FDA.
This side effect wasn’t reported in human studies of Mounjaro. Animal studies have shown a risk for this side effect, but animal studies don’t always predict what will happen in humans. Still, due to this possible risk, Mounjaro is not recommended for people who have had a certain type of thyroid cancer or a family history of it.
With thyroid cancer, the thyroid gland has abnormal and uncontrolled cell growth. These cancer cells can spread to other parts of the body. The thyroid gland makes hormones that help regulate your metabolism and other body functions.
Symptoms of thyroid tumors or thyroid cancer include:
- swelling or a lump on the neck or throat
- neck pain
- trouble swallowing
- hoarseness
- shortness of breath
Ways to manage
If you develop any symptoms of thyroid tumors or thyroid cancer while using Mounjaro, such as a lump on your neck, contact your doctor right away.
Before you start Mounjaro, tell your doctor about your medical history and family history. They can discuss the risks and benefits of treatment with you.
Nausea and vomiting
In studies, nausea and vomiting were common side effects in people using Mounjaro injection. Nausea is a feeling of stomach upset and the need to vomit. Vomiting is throwing up the contents of the stomach. These side effects of Mounjaro injection are usually mild. Nausea occurred more often than vomiting.
Most people reporting nausea and vomiting in studies had these side effects while the dose of Mounjaro was being increased. These side effects decreased over time.
More severe nausea and vomiting could lead to dehydration. This could increase the risk of acute kidney injury, especially in people who already have kidney problems.
Ways to manage
If you experience nausea or vomiting, tell your doctor. They’ll likely recommend ways to help limit these side effects, such as:
- stopping eating when full
- eating smaller, more frequent meals
- limiting high fat, greasy, or spicy foods
- eating foods that may be less likely to cause nausea, such as crackers, toast, or cereal
If you’re having these side effects or they persist, your doctor may also increase your dosage of Mounjaro more slowly.
If you have nausea, vomiting, or diarrhea, be sure to drink enough fluids to help prevent dehydration.
Constipation
In studies, constipation was common in people using Mounjaro. It’s usually mild and should get better with time.
Symptoms of constipation may include:
- dry, hard, or lumpy stools
- feeling full even after a bowel movement
- straining or difficulty passing stool
Ways to manage
If you experience bothersome symptoms of constipation or your symptoms don’t improve, tell your doctor. They may recommend steps to help prevent constipation, such as:
- eating foods rich in fiber, such as fruits, vegetables, and whole grains
- drinking enough water
- getting physical activity
- not delaying when you feel the urge to have a bowel movement
Allergic reaction
For some people, Mounjaro injection can cause an allergic reaction. This side effect was reported in the drug’s studies.
Symptoms can be mild or serious, and they may include:
- itchiness
- skin rash
- swelling under the skin, usually affecting eyelids, lips, hands, or feet
- swelling of the mouth, tongue, or throat, which can make it hard to breathe
- flushing (temporary warmth, redness, or deepening of skin color)
Ways to manage
For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep using the medication.
For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to Mounjaro, your doctor may recommend using a different medication instead.
Warnings for Mounjaro
Below are some factors you may want to discuss with your doctor before using Mounjaro.
Boxed warning: Risk of thyroid tumors and thyroid cancer
Mounjaro has a boxed warning for the risk of thyroid tumors and thyroid cancer. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).
For details, see the “Side effects of Mounjaro in detail” section above.
Other warnings
It may not be safe for you to use Mounjaro injection if you have specific health conditions. These are sometimes called drug-condition interactions. Other things may also affect whether Mounjaro is a safe treatment option for you.
Before using Mounjaro, tell your doctor about your health and medications you take. Things to consider include:
- problems with your kidneys or pancreas
- serious problems with your stomach or digestion
- diabetic retinopathy (damage to a part of your eye called the retina, which can occur if you have diabetes)
- pregnancy or breastfeeding
- whether you take birth control pills by mouth
- whether you take insulin or certain other diabetes medications
- past allergic reaction to Mounjaro
Mounjaro and pregnancy
It’s not known whether Mounjaro injection should be used during pregnancy. If you’re planning a pregnancy or can become pregnant, talk with your doctor before using this medication.
If you’re taking birth control pills by mouth, they may not work as well while you’re using Mounjaro. One way that Mounjaro works is it slows how quickly your stomach empties. This means that birth control pills may not be absorbed as well as they usually are. Talk with your doctor before starting Mounjaro if you take birth control pills. They can discuss birth control methods with you and whether any adjustments may be needed.
Mounjaro and breastfeeding
It’s not known whether Mounjaro injection should be used while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before using this medication.
Mounjaro and alcohol
Mounjaro injection is not known to interact with alcohol. But drinking alcohol may cause hypoglycemia (low blood sugar levels). Mounjaro also lowers blood sugar. So the risk of low blood sugar levels may be higher if you consume alcohol while using Mounjaro, especially if you also take some other diabetes medications, such as insulin.
If you drink alcohol, talk with your doctor about whether it’s safe to consume it during your treatment with Mounjaro injection. See this article for more details about how alcohol can affect your blood sugar.
What to ask your doctor
This article describes common and serious side effects of Mounjaro injection. If your doctor prescribes this medication, they can discuss possible side effects with you. Let your doctor know if you have concerns or questions about treatment with this medication.
Here’s a list of some possible questions you may want to ask your doctor:
- Does my dose of Mounjaro affect how likely I am to have side effects?
- What are ways to help limit the risk of side effects with Mounjaro injection?
- How long are side effects of Mounjaro injection likely to last?
- Can Mounjaro injection cause hair loss?
- Are there other drugs that could be used to treat my condition that may have fewer side effects?
Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.