Is Mounjaro safe?

In this article:

• Is Mounjaro safe?
• Common side effects
• Contraindications
• Navigating Mounjaro use
• Approved vs. off-label use
• Is Mounjaro right for you?

In this article

• Is Mounjaro safe?
• Common side effects
• Contraindications
• Navigating Mounjaro use
• Approved vs. off-label use
• Is Mounjaro right for you?

Mounjaro (tirzepatide) is a brand-name Type 2 diabetes medication manufactured by Eli Lilly. It is a dual GLP-1 and GIP agonist, meaning it acts on both the glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptors. 

Mounjaro (tirzepatide) is a prescription medication approved by the U.S. Food and Drug Administration to treat Type 2 diabetes. As a dual GLP-1 and GIP receptor agonist, it helps regulate blood sugar by targeting two hormone pathways involved in glucose control.

Because tirzepatide is also marketed under a different brand name for weight management, Zepbound, many people wonder whether Mounjaro is safe, especially when used beyond its FDA-approved indication. Clinical trials show that Mounjaro is generally safe and effective for adults with Type 2 diabetes who do not have contraindications. However, as with any medication, side effects and risks are possible, and safety can vary based on individual health factors.

Is Mounjaro generally considered safe?

“Mounjaro is considered safe for people with Type 2 diabetes who meet the approved criteria and have no contraindications to its use,” says Jennifer Brown, MD, an obesity medicine specialist based in West Virginia. This is based on FDA approval of Mounjaro, which is supported by nine clinical trials involving more than 5,400 patients with Type 2 diabetes. “The FDA ensures that a drug’s benefits outweigh its risks prior to approving it for use,” Dr. Brown says. FDA drug approval is a rigorous process, Dr. Brown adds, and approved medications are continuously monitored for safety.

While much of what we know about Mounjaro safety comes from studies involving adult participants, it’s also considered safe and effective for children ages 10 and older with Type 2 diabetes. Many of the safety concerns have to do with common side effects, such as injection site reactions and those that are gastrointestinal (GI), as well as dosing errors. 

“Mounjaro is one of the most effective medications available for the treatment of Type 2 diabetes and obesity,” Dr. Brown says. For example, tirzepatide has been shown to significantly improve blood sugar levels and body weight in those with Type 2 diabetes compared to insulin glargine. Though effective, insulin is associated with weight gain and can cause life-threatening hypoglycemia if used incorrectly, Dr. Brown says. “Oral anti-diabetic medications, such as metformin or glyburide, aren’t nearly as effective and often have limiting side effects,” Dr. Brown says.

What to expect and when to be concerned

Diabetes medications, including Mounjaro, can come with some common side effects. Some are mild, while serious side effects may warrant immediate medical attention.

“The most common side effects include nausea, vomiting, constipation, and stomach pain,” Dr. Brown says. These more common side effects mainly affect the GI tract, which is consistent with how Mounjaro works. “Mounjaro slows down the speed of gastric emptying, which can lead to these side effects,” Dr. Brown says. Up to 49% of people who take tirzepatide experience GI side effects, with nausea and diarrhea being the most common. As the dose of tirzepatide increases, the likelihood of side effects increases as well.

Serious side effects can also occur. According to data from drug trials, Mounjaro can cause the following:

• Inflammation of the pancreas (pancreatitis)
• Low blood sugar (hypoglycemia)
• Allergic reactions
• Kidney problems (kidney failure)
• Severe stomach problems
• Diabetic retinopathy

“Anyone who takes Mounjaro and experiences severe stomach pain, persistent vomiting, fainting, swelling of lips and tongue, or problems breathing should seek medical care immediately,” Dr. Brown says.

Who should not use Mounjaro?

Even though Mounjaro is generally considered safe, some people may be at increased risk of adverse effects.

“Those with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia syndrome Type 2 should never take Mounjaro,” Dr. Brown says. Mounjaro comes with a black box warning about causing thyroid tumors, based on an association observed in animal studies, though it’s currently unclear whether this applies to humans.

Mounjaro also comes with other precautions. “In addition, anyone with a history of pancreatitis, gastroparesis, or severe kidney disease should be closely monitored by their healthcare provider for adverse effects,” Dr. Brown adds.

Navigating Mounjaro use

To ensure Mounjaro is right for you, your prescribing physician should have a complete picture of your medical history. “Open communication is very important, and we need complete honesty,” says Supriya Rao, MD, an obesity medicine provider based in the Greater Boston area. “The more we know, the more we can help provide strategic support.”

Before starting the medication, be prepared to share your full medical history, including any health conditions. This also includes your lifestyle habits, such as your diet and exercise routine, as well as any over-the-counter supplements and prescription medications you currently take. “The more transparent you are, the better,” Dr. Rao says.

Once you start Mounjaro, your healthcare provider will want updates on how you’re tolerating the medication so they can adjust your dose and monitor your health. “Doses are adjusted gradually, and side effects need to be talked about,” Dr. Rao says. Given how common dosing errors are—they’re one of the most common adverse effects of Mounjaro—it’s critical to adhere to your prescribing provider’s instructions on dosing and timing. 

You can also expect your healthcare provider to monitor your progress and order the necessary health tests. “I’ll monitor body weight, labs, blood sugar levels, and any symptoms,” Dr. Rao adds.

Distinguishing between on-label and off-label use

Mounjaro is FDA-approved for Type 2 diabetes because it can lower blood sugar levels, but weight loss is a common side effect. So, it’s sometimes prescribed off-label for weight management.

“On-label means the FDA has formally approved the medication for a specific condition based on clinical trials,” Dr. Rao explains. “Off-label means we’re prescribing it for a condition outside that formal approval.”

What does this mean for safety? “The safety profile of the drug itself doesn’t suddenly change because of the label,” Dr. Rao says.

Still, it’s important to use Mounjaro only under the supervision of a healthcare professional. There are also times to heed caution when using Mounjaro off-label or compounded versions of the medication.

“While physicians can prescribe Mounjaro for off-label reasons, such as weight loss in those who aren’t technically obese, the FDA has not evaluated the drug for safety for these uses,” Dr. Brown says. “I generally avoid off-label use of Mounjaro because rigorous safety data are not available.”

There’s also the decision between brand-name Mounjaro vs compounded tirzepatide. While the latter may be an attractive option for its affordability, it may not have the same safety profile or reliability as Mounjaro. “What you don’t want is a compounded GLP-1,” Dr. Rao says. “Those variations are not FDA-approved, may vary in quality or dosing, and don’t undergo the same rigorous safety oversight as the branded medication.”

Is Mounjaro right for you?

Mounjaro is generally considered safe when prescribed for its FDA-indicated use in people with Type 2 diabetes. This comes from several clinical trials involving thousands of participants. Still, side effects are possible. While most are mild, particularly those affecting the GI tract, more serious side effects can occur in rare cases.

Outside of its approved use, Mounjaro may be prescribed for weight management. It’s clear that Mounjaro can cause weight loss, but the safety data for this use isn’t as robust.

Mounjaro could be right for you if you have Type 2 diabetes and don’t have any contraindications. You’ll also want to account for your health history and other medications you currently take. Once you start the medication, it’s also wise to consider your tolerance for side effects and commitment to lifestyle changes. Fortunately, your prescribing healthcare provider can help you navigate this.