Skip to main content

Does Mounjaro cause fatigue?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on Feb 22, 2023.

Official answer


Mounjaro (generic name: tirzepatide) does not usually cause fatigue, which can leave you feeling tired, weak and with low energy. However, fatigue can be a common side effect associated with type 2 diabetes. Talk to your doctor if your symptoms of fatigue continue or are severe.

Some people have complained of fatigue after using Mounjaro as seen in the Mounjaro User Reviews, but the manufacturer did not report this side effect.

Learn more: User Reviews for Mounjaro

Symptoms of type 2 diabetes include:

  • extreme thirst
  • frequent urination
  • always feeling hungry
  • unexpected weight loss
  • fatigue, weakness or tiredness
  • blurred vision
  • sores that heal slowly
  • frequent infections
  • numbness or tingling in the hands or feet
  • areas of darkened skin, usually in the armpits and neck

Mounjaro injection is approved as a once-weekly injectin to treat high blood sugar levels in adults with type 2 diabetes, used alongside diet and exercise. With type 2 diabetes, your body does not use your blood sugar properly leading to high levels in your circulation. High blood sugars can lead to health complications over time, such as nervous system, immune and heart conditions.

When was Mounjaro approved by the FDA?

Mounjaro (tirzepatide) injection was approved by the FDA in May 2022. It is used to improve blood sugar (glucose) control in adults with type 2 diabetes. You should use it with a diet and exercise plan as recommended by your doctor. It is injected under the skin (subcutaneously) of your stomach (abdomen), thigh, or upper arm one time per week, at any time of the day.

What side effects should I expect with Mounjaro?

Stomach (gastrointestinal) side effects are the most common side effects reported in studies with Mounjaro. Higher doses may be associated with more frequent stomach side effects. Most side effects with Mounjaro usually go away in days to weeks after starting treatment.

Side effects reported in at least 5% of patients included:

  • nausea
  • diarrhea
  • decreased appetite
  • vomiting
  • constipation
  • indigestion, heartburn (dyspepsia)
  • stomach (abdominal) pain.

Serious side effects include: pancreatitis (inflammation of the pancreas); hypoglycemia (low blood sugar) with use of other diabetes treatments; allergies which can be severe; sudden (acute) kidney injury; severe gastrointestinal (digestive tract) disease; diabetic retinopathy (eye disease) complications; sudden (acute) gallbladder disease.

The package insert also carries a Boxed Warning for thyroid C-cell tumors. Mounjaro causes thyroid C-cell tumors in rats, but this occurrence in human is not known.

  • Do not use this medicine if you or any of your family have ever had a type of thyroid cancer called medullary thyroid carcinoma (MTC), or if you have an endocrine system condition called Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
  • Tell your healthcare provider if you get a lump or swelling in your neck, hoarseness, trouble swallowing, or shortness of breath. These may be symptoms of thyroid cancer.

Related: Mounjaro side effects (in more detail)

This is not all the information you need to know about Mounjaro (tirzepatide) for safe and effective use and does not take the place of your doctor’s directions. Review the full Mounjaro information and discuss this information and any questions you have with your doctor or other health care provider.


Related medical questions

Drug information

Related support groups