Tirzepatide Side Effects: Zepbound and Mounjaro

Short answer: the most common tirzepatide side effects are stomach-related: nausea, diarrhea, vomiting, constipation, and abdominal pain. The Zepbound label also lists injection site reactions, fatigue, and hair loss among effects reported by at least 5% of people. There is a boxed warning about thyroid C-cell tumors seen in rats.

Zepbound (weight management): reported by 5% or more

• Nausea, diarrhea, vomiting, constipation, abdominal pain
• Dyspepsia (indigestion) and eructation (burping)
• Injection site reactions
• Fatigue
• Hypersensitivity reactions
• Hair loss
• Gastroesophageal reflux disease

Mounjaro (type 2 diabetes): reported by 5% or more

• Nausea, diarrhea, vomiting, constipation, abdominal pain
• Decreased appetite
• Dyspepsia

Stomach effects are usually most noticeable while the dose is being raised, which is why the labeled schedule increases in small steps of at least 4 weeks each.

The boxed warning

In rats, tirzepatide caused thyroid C-cell tumors. It is unknown whether it causes these tumors, including medullary thyroid carcinoma, in humans. It is not for people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2.

Other warnings on the labels

• Severe gastrointestinal reactions, and it is not recommended in severe gastroparesis
• Acute kidney injury from dehydration
• Acute gallbladder disease
• Acute pancreatitis
• Serious hypersensitivity reactions such as anaphylaxis and angioedema
• Low blood sugar when combined with insulin or sulfonylureas
• Diabetic retinopathy complications
• Risk of aspiration during anesthesia or deep sedation

Long-term use

Weight-management treatment is meant to be long term, so ongoing check-ins with your provider matter. The lists above are summaries, not the full label. Your prescriber and pharmacist can walk through the complete prescribing information with you.