Common adverse reactions
Zepbound and Mounjaro have different product-specific reaction tables
The current Eli Lilly Zepbound and Mounjaro prescribing information was updated April 22, 2026. Both products contain tirzepatide for subcutaneous injection, but they have different indications, study populations, presentations, and adverse-reaction tables. Zepbound labeling lists nausea, diarrhea, vomiting, constipation, abdominal pain, dyspepsia, injection-site reactions, fatigue, hypersensitivity reactions, eructation, hair loss, and gastroesophageal reflux disease among reactions reported in at least 5% of treated patients. Mounjaro labeling lists nausea, diarrhea, decreased appetite, vomiting, constipation, dyspepsia, and abdominal pain at that threshold.
- Do not combine the lists, compare percentages as though the trials were head-to-head, or use one product table as a universal tirzepatide rate.
- Mounjaro is labeled for adults and pediatric patients age 10 and older with type 2 diabetes; Peptide12 provides adult care and should not misstate the broader manufacturer label.
- Report symptoms that are persistent, recurrent, worsening, severe, intake-limiting, or disruptive even when they appear on a common-reaction list.
Digestive effects, hydration, and glucose
Nausea, vomiting, diarrhea, and constipation need symptom-specific review
Both labels describe gastrointestinal adverse reactions and note that many nausea, vomiting, and diarrhea events occurred during dose escalation and decreased over time in their respective trials. That group-level observation does not give one person a guaranteed start date, duration, or safe waiting period. Both labels also warn about kidney injury due to volume depletion, while low-blood-sugar risk can increase when tirzepatide is used with insulin or an insulin secretagogue such as a sulfonylurea.
- Record vomiting or diarrhea episodes, bowel pattern, ability to keep fluids and food down, urine amount and color, dizziness, fainting, weakness, and recent illness or heat exposure.
- If glucose monitoring is part of care, record readings with symptoms, meals, activity, alcohol, insulin, sulfonylureas, and other glucose-lowering medicines.
- Do not improvise a treatment hold, catch-up injection, restart, anti-nausea medicine, laxative, hydration recipe, or glucose plan from generic online advice.
Serious label warnings
Common stomach symptoms should not obscure urgent abdominal, allergy, or thyroid signs
Current Zepbound and Mounjaro labels include a boxed warning about thyroid C-cell tumors observed in rats; it is unknown whether tirzepatide causes these tumors in humans. The products are contraindicated with a personal or family history of medullary thyroid carcinoma or MEN 2. The labels also address acute pancreatitis, gallbladder disease, severe gastrointestinal reactions, kidney injury from volume depletion, serious hypersensitivity, and pulmonary aspiration during anesthesia or deep sedation. A page cannot diagnose these conditions or replace an examination.
- Seek prompt care for severe or persistent abdominal pain, especially pain that may spread to the back, with or without nausea or vomiting; jaundice, fever, or right-upper-abdominal pain also needs assessment.
- Trouble breathing or swallowing, facial or throat swelling, fainting, widespread hives, a neck mass, persistent hoarseness, or rapidly developing serious symptoms requires urgent or emergency evaluation.
- Tell the procedure and anesthesia team about the exact tirzepatide product, symptoms, and treatment timing; do not create a self-directed hold or restart schedule.
Other medicines and absorption
Diabetes medicines, oral drugs, pregnancy plans, and procedures can change the review
Tirzepatide delays gastric emptying and may affect absorption of oral medicines. Current labeling includes specific oral-hormonal-contraceptive guidance after treatment initiation and after each clinician-directed dose escalation. Pregnancy, severe gastroparesis, diabetes treatment, kidney risk, oral medicines with narrow safety margins, and upcoming anesthesia or deep sedation can all change what the responsible clinician needs to review. No universal online timing or spacing rule replaces the product label and patient-specific plan.
- Share insulin, sulfonylureas, other diabetes medicines, oral contraceptives, narrow-therapeutic-index medicines, kidney history, severe stomach-emptying symptoms, pregnancy plans, and upcoming procedures.
- Preserve the exact product, presentation, prescription and pharmacy label, strength or concentration, refill or lot details, and storage history.
- Contact the prescriber or pharmacist before changing tirzepatide, another diabetes medicine, contraception, or any important oral medicine.
Compounded-product boundary
Branded label rates do not establish compounded-tirzepatide safety or quality
Zepbound and Mounjaro are FDA-approved finished tirzepatide products with product-specific indications, presentations, instructions, and evidence. A patient-specific compounded tirzepatide injection is not an FDA-approved Zepbound or Mounjaro finished product and is not an FDA-approved generic tirzepatide. It may differ in concentration, inactive ingredients, container, supplies, labeling, storage, and beyond-use date. A symptom after a refill or product change should prompt verification of the current prescription label and dispensing pharmacy.
- Do not transfer Zepbound or Mounjaro percentages, pen instructions, storage rules, or presentation assumptions to a compounded vial.
- Avoid research-use products, unlabeled vials, counterfeit pens, copied syringe charts, unverified additive combinations, and no-prescription sellers.
- A stronger reaction does not prove potency, purity, better absorption, or better weight or glucose results.