Your doctor will decide whether it’s safe for you to use Mounjaro for weight loss. A doctor may prescribe Mounjaro off-label for weight loss in adults with either: 

a body mass index (BMI) of 30 or higher (obesity), or 

a BMI of 27 or higher (which is considered overweight) and at least one health condition related to weight, such as high blood pressure, high cholesterol, or obstructive sleep apnea 

This is because tirzepatide (the active drug in Mounjaro) was shown to help with weight loss in adults meeting either of these qualifications in studies. 

Mounjaro is prescribed along with exercise and a balanced diet, which can help with weight management. 

To start, your doctor will typically prescribe a low dosage of Mounjaro. For example, a likely starting dosage is 2.5 milligrams (mg) injected once weekly for 4 weeks. Then, your doctor will likely increase your Mounjaro dose by 2.5 mg every 4 weeks until they reach a dose that helps with weight loss.

Mounjaro comes as a solution in a single-use injection pen. You’ll inject the drug under the skin of your thigh or abdomen. Or you can have a caregiver inject the drug under the skin of your outer upper arm.

Each of the injection sites for Mounjaro (your thigh, abdomen, or upper arm) are thought to be equally effective. Be sure to inject Mounjaro only in these areas.

Also, you should:

Use a different injection site for each dose of Mounjaro. For example, if you inject the drug in your thigh, next week you should use a different place on your thigh or inject the drug into your abdomen instead. Do not inject Mounjaro into the exact same spot more than once.

Avoid injecting Mounjaro in areas where your skin is thickened, tender, bruised, hardened, scarred, or damaged. Also do not inject into areas where your skin has lumps or pits.

You’ll inject Mounjaro once weekly, usually on the same day each week. You can inject the drug any time of day. 

Some people may have mild side effects with Mounjaro. These include:

• mild increase in heart rate

• mild digestive problems, such as heartburn, abdominal pain, nausea, and diarrhea

• injection site reactions, such as skin discoloration or pain

In many cases, mild side effects from the drug can be temporary. Some side effects may be easy to manage, too. But if side effects last for a longer time, or if they bother you or become severe, talk with your doctor or pharmacist.

Using Mounjaro may lead to serious side effects, although these are rare. Examples of these side effects include:

• low blood sugar

• sudden pancreatitis (inflammation of your pancreas)

• sudden gallbladder disease, which may include cholecystitis (swelling of your gallbladder) or gallstones

• severe digestive problems, such as severe vomiting, nausea, or diarrhea, which can lead to dehydration and kidney problems

• worsening of eye problems, in people with diabetes

• boxed warning: risk of thyroid cancer

• allergic reaction

• Type 1 diabetes

• Personal or family history of medullary thyroid carcinoma (MTC)

• History of Multiple Endocrine Neoplasia syndrome type 2 (MEN 2)

• Pancreatitis (history or current)

• Severe gastrointestinal disease (e.g., gastroparesis)

• Pregnant or breastfeeding

• Allergy to tirzepatide or any component of the injection

• Severe renal impairment (eGFR under 30) — use with caution

• Active eating disorders

• Underweight clients (BMI under 25) unless diabetic under endocrinologist care

• BMI ≥30 (Obese)

• BMI ≥27 with comorbidities (hypertension, PCOS, prediabetes, sleep apnea)

• Stable thyroid and kidney function

• Committed to lifestyle changes (diet + activity)

• Over 18 years old

• Not pregnant, breastfeeding, or planning pregnancy

• No contraindicated medical history (as listed above)