Mounjaro can be effective in reducing A1c levels and helping with weight management. However, it has potential side effects that may affect your everyday life.

This article will explain everything you need to know about the side effects of Mounjaro.

Doctor speaks with a patient

Key facts

  • Mounjaro, known generally as tirzepatide, is a once-weekly injectable medication approved by the FDA in 2022 for managing type 2 diabetes. It uniquely activates both GLP-1 and GIP receptors, helping with blood sugar control and weight management.
  • The drug functions by increasing insulin production when blood sugar levels are high, reducing the liver’s glucose release, slowing digestion, and improving how well the body’s cells respond to insulin.
  • While Mounjaro can cause common side effects like nausea, vomiting, and gastrointestinal discomfort, it may also lead to severe issues such as thyroid tumors, pancreatitis, and serious allergic reactions. Monitoring and immediate medical attention for severe symptoms are crucial.
  • To minimize side effects, strategies like adjusting the dose, staying hydrated, eating bland foods, and possibly using over-the-counter medications are recommended.

Table of Contents

How does Mounjaro work?

Mounjaro helps control blood sugar levels by making the pancreas release insulin only when blood sugar is high, which reduces the risk of hypoglycemia (low blood sugar). 

It also increases insulin sensitivity,  helping the body use insulin more effectively, and stops the liver from releasing too much sugar into your bloodstream. 

Additionally, Mounjaro helps with weight management by reducing hunger and slowing down digestion, making people feel fuller for longer. 

What are the side effects of Mounjaro?

Mounjaro can have some major side effects, especially when you first start taking the medication. 

Common side effects

The following are common side effects that may range from mild to moderate to severe: 

  • Nausea
  • Vomiting 
  • Diarrhea 
  • Bloating
  • Belching
  • Heartburn
  • Appetite loss
  • Gas
  • Stomach pain
  • Constipation 
  • Weight loss 
  • Rapid heart rate 

Rare side effects

Although rare, more severe complications may include: 

  • Thyroid tumors, including cancer 
  • Pancreatitis 
  • Gallbladder disease 
  • Low blood sugar levels, especially if you take insulin or another medicine that promotes the release of insulin
  • Serious allergic reactions

Several of these more severe side effects can lead to permanent health complications and death if not treated quickly. 

Call your doctor immediately or seek emergency medical attention if you:

  • Develop a fever 
  • Experience changes or worsening of your vision 
  • Start feeling weak or develop pain after taking the medication 
  • Think you’re having an allergic reaction and are experiencing trouble breathing or a rash after taking the medication 

Additionally, Mounjaro should not be used in people with a personal or family history of medullary thyroid carcinoma (MTC) or in those with multiple endocrine neoplasia 2 (MEN2) syndrome.

The medicine includes a boxed warning — the most serious warning from the FDA — about the risk of thyroid cancer.

For more information about Mounjaro’s possible side effects, see the prescribing information.

Note from the FDA

Following the approval of a medication by the FDA, the agency continues to monitor its side effects. Should you experience any adverse effects from using Mounjaro, you are encouraged to report them to the FDA through their MedWatch program.

How can you decrease the side effects of Mounjaro?

After starting this medication, it’s normal to experience mild to moderate side effects — especially during the first few weeks.

Stay hydrated and keep blood sugars within a healthy range 

If you’re dealing with nausea, vomiting, and diarrhea, make sure that you’re staying hydrated by drinking plenty of water and getting electrolytes. 

Being dehydrated increases the risk of diabetic ketoacidosis (DKA), which can be fatal if not treated quickly. 

Check your blood sugar often to make sure that your levels are staying within a healthy range. 

Continue to take all other diabetes medications as prescribed. 

Seek medical attention immediately if you’re so nauseous that you’re not able to keep down food or drink. Untreated low blood sugar can be extremely dangerous, especially if you take insulin. 

Stick to bland foods in the beginning 

Manage nausea by sticking to bland foods such as toast, rice, bananas, and applesauce. 

Also drink plenty of clear liquids, such as warm soups and broths. 

Learn more about this medication and diet in: What Foods to Avoid on Mounjaro.

Eat smaller, more frequent meals 

You may also find it helpful to eat smaller, more frequent meals. Stop eating once you are full, even if you seem to be eating less than normal.

Lower your dose or find an alternative medication

Talk to your doctor if the side effects you’re experiencing are severe enough to disrupt your daily life. 

If you cannot go to school, work, or conduct normal activities, your doctor may suggest either tapering your dose or finding an alternative medication

Opt for over-the-counter medications 

After consulting with your doctor, you can also take over-the-counter (OTC) nausea medication such as dimenhydrinate (brand names Dramamine and others) or get a prescription for ondansetron (Zofran) until your side effects subside. 

Does taking more Mounjaro make side effects worse?

Mounjaro is dose-responsive. This means that taking more of the medication will have a bigger effect on your blood sugar levels and weight. 

However, this also means that you may be more likely to experience side effects the more you take. 

You should never take more Mounjaro than you’re prescribed. Your doctor may increase your dose as your body gets used to the medication. 

Read more: Mounjaro Dosing Guide.

Are side effects expected?

Unfortunately, many people do experience one or more side effects when taking Mounjaro. 

In clinical trials, nearly one in five participants experienced either nausea, diarrhea, or decreased appetite when taking the medication. 

Other side effects, such as vomiting and constipation, were less common. 

How long do the side effects last?

Some side effects may be temporary and last only a few days or weeks. Talk to your doctor if your side effects last more than a few weeks or get worse. 

Your doctor can work with you to lower your dose or find an alternative medication. 

Does Mounjaro make you tired?

Tiredness was not reported as one of the side effects of the medicine in clinical trials. 

However, side effects such as nausea, vomiting, loss of appetite, and pancreatitis can be associated with fatigue. Tiredness can also be a sign of low blood sugar. 

Do you have to take Mounjaro with food?

No. Unlike insulin, Mounjaro does not cause acute low blood sugars and can be taken either with or without food. 

The important thing is that you take your Mounjaro on the same day at the same time each week. 

Who should not take Mounjaro?

Mounjaro is not suitable for everyone, including people without diabetes, pregnant or breastfeeding women, and those with a history of certain thyroid cancers or allergies to the drug’s ingredients.

Are there alternatives to Mounjaro?

Yes. Speak with your doctor if Mounjaro is not working for you. 

There are many alternatives you can try, including metformin or medicines in the drug classes known as GLP-1 agonists or sodium-glucose co-transporter-2 (SGLT-2) inhibitors.

Metformin brand names include:

  • Fortamet
  • Glucophage
  • Glucophage XR
  • Glumetza
  • Riomet
  • Riomet ER

GLP-1 receptor agonists include:

SGLT-2 inhibitors include:

Speak with your doctor about what class and type of medication would be best for you.