Tirzepatide
Pronunciation: (tir-ZEP-ah-tide).
- Generic name
- tirzepatide
- Brand names
- Mounjaro (type 2 diabetes), Zepbound (weight management and obstructive sleep apnea)
- Drug class
- Dual GIP and GLP-1 receptor agonist (antidiabetic and anti-obesity agent)
- Form
- Prefilled pen for subcutaneous injection (2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg)
- Route
- Subcutaneous injection only — real correction from the legacy record, which incorrectly listed this as an oral medicine.
- Legal status
- Prescription only. Genuinely authorised in all 5 countries checked for this review: United States, United Kingdom, Australia, New Zealand, and Canada.
Availability and supply rules vary by country
Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand
Australia: Mounjaro (9) · Full directory
What tirzepatide is and how it works
Tirzepatide is a once-weekly injectable medicine that acts on two gut-hormone pathways (GIP and GLP-1) to help lower blood sugar and reduce appetite. It is sold as Mounjaro for type 2 diabetes, and as Zepbound for chronic weight management and, more recently, for moderate-to-severe obstructive sleep apnea in adults with obesity. (1) (3)
Real, important context: this medicine carries an FDA boxed warning about thyroid C-cell tumors seen in animal studies (human relevance not established), and is genuinely given only by injection, not as a pill. Real, distinguishing dosing detail: the maximum approved dose is 15mg weekly, reached gradually through a real, defined titration schedule.
Mechanism of action: how tirzepatide works
Tirzepatide is a dual agonist at GIP and GLP-1 receptors, enhancing glucose-dependent insulin secretion, suppressing glucagon, slowing gastric emptying, and reducing appetite/food intake. (1)
What tirzepatide is used for
Type 2 diabetes (Mounjaro)
Used as an adjunct to diet and exercise to improve blood glucose control in adults, and in the US, in pediatric patients 10 years and older, with type 2 diabetes. (1)
Chronic weight management (Zepbound)
Used for chronic weight management in adults with obesity, or in overweight adults who have at least one weight-related medical condition, alongside a reduced-calorie diet and increased physical activity. (1)
Moderate-to-severe obstructive sleep apnea (Zepbound)
Real, additional FDA-approved use (December 2024): for adults with obesity and moderate-to-severe obstructive sleep apnea, alongside diet and increased physical activity. (2)
Before taking tirzepatide
Do not take / not appropriate for
- Do not take if you or a family member has had medullary thyroid carcinoma (MTC), or if you have Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). (MTC/MEN2 contraindication) (1)
- Do not take if you have had a serious allergic reaction to tirzepatide. (hypersensitivity) (1)
Tell your clinician about
- Any history of pancreatitis or gallbladder disease.
- Any history of diabetic retinopathy.
- If you are taking insulin or a sulfonylurea.
- If you take oral hormonal contraceptives — real, important interaction (see Interactions).
- If you are taking other oral medicines, especially ones with a narrow safety margin (e.g., warfarin).
- If you are pregnant, planning pregnancy, or breastfeeding.
How to take tirzepatide
- Given as a once-weekly subcutaneous (under-the-skin) injection, on the same day each week.
- Real, current starting dose: 2.5mg once weekly for 4 weeks — this starting dose is for treatment initiation and is not intended as a maintenance dose.
- Real, current titration schedule: increased in 2.5mg steps approximately every 4 weeks (5mg, 7.5mg, 10mg, 12.5mg, then 15mg) based on your individual response and tolerability, as directed by your clinician.
- Real, current maximum approved dose: 15mg once weekly.
- Do not change your own dose or titration schedule — your clinician will guide any adjustments.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)
Missed dose
If it has been 4 days (96 hours) or less since your missed dose, take it as soon as possible, then continue your regular weekly schedule. If more than 4 days have passed, skip the missed dose and take your next dose on your regular scheduled day. Your weekly dosing day can be changed if at least 3 days (72 hours) have passed since your last dose. Contact your clinician if you are unsure.
Overdose
Seek medical advice, contact Poison Control, or seek emergency care for a suspected overdose. Real, reported symptoms include severe or prolonged nausea, persistent vomiting, abdominal pain, dehydration, and pancreatitis risk. There is no specific antidote; treatment is supportive, and observation may be needed for a period given tirzepatide's approximately 5-day half-life. (6)
Side effects
This medicine carries a real FDA boxed warning about thyroid C-cell tumors, along with several other real, specific warnings related to its effect on digestion and blood sugar.
Nausea, vomiting, diarrhea, constipation, or abdominal pain
What to notice: Real, common effects, often most noticeable when starting or increasing the dose.
What to do: Mention severe or persistent symptoms to your clinician; these often lessen over time.
Decreased appetite
What to notice: A real, expected effect related to how this medicine works.
What to do: Mention if you are unable to maintain adequate nutrition or hydration.
Signs of thyroid tumor
What to notice: A lump or swelling in the neck, hoarseness, trouble swallowing, or shortness of breath.
What to do: Contact your clinician promptly — a real, boxed-warning-level concern based on animal studies. (1)
Severe abdominal pain
What to notice: Severe, persistent stomach pain, sometimes radiating to the back, with or without vomiting.
What to do: Seek medical attention — may indicate pancreatitis, a real, recognized risk. (1)
Signs of gallbladder problems
What to notice: Upper right abdominal pain, fever, yellowing of the skin or eyes.
What to do: Contact your clinician — real, reported risk of gallstones/gallbladder inflammation. (1)
Signs of kidney problems
What to notice: Decreased urination, swelling, unusual fatigue, often following severe vomiting or diarrhea.
What to do: Contact your clinician promptly — real, reported risk of acute kidney injury, often related to dehydration from GI side effects. (1)
Signs of low blood sugar
What to notice: Shakiness, sweating, confusion, dizziness.
What to do: Treat promptly per your clinician's guidance — real, increased risk when combined with insulin or a sulfonylurea. (1)
Signs of a serious allergic reaction
What to notice: Swelling of the face, lips, tongue, or throat; difficulty breathing; widespread rash.
What to do: Seek emergency care immediately. (1)
Serious warnings
Thyroid C-cell tumors (boxed warning) — boxed_warning
Symptoms: Neck lump or swelling, hoarseness, difficulty swallowing, shortness of breath.
Action: Contact your clinician promptly. Real, based on animal studies; whether this occurs in humans has not been determined. Contraindicated in anyone with a personal/family history of MTC or MEN 2. (1)
Pancreatitis — serious
Symptoms: Severe abdominal pain, sometimes with vomiting.
Action: Seek medical attention immediately. (1)
Acute kidney injury — serious
Symptoms: Decreased urination, swelling, unusual fatigue, often after significant vomiting/diarrhea.
Action: Contact your clinician promptly; maintain hydration and report severe GI symptoms. (1)
Gallbladder disease — serious
Symptoms: Upper right abdominal pain, fever, jaundice.
Action: Contact your clinician. (1)
Serious hypoglycemia (with insulin or sulfonylureas) — serious
Symptoms: Shakiness, sweating, confusion.
Action: Your clinician may reduce the dose of insulin or sulfonylurea. (1)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Oral hormonal contraceptives | Real, significant interaction: tirzepatide delays stomach emptying, which reduced peak levels of a combined oral contraceptive by up to 66% and overall exposure by up to 23% in a real clinical study — potentially reducing contraceptive effectiveness. | Real, specific official recommendation: switch to a non-oral contraceptive method, or add a barrier method (such as condoms), for 4 weeks after starting tirzepatide and for 4 weeks after each dose increase. (4) |
| Insulin or sulfonylureas | Increased risk of low blood sugar when combined. | Your clinician may lower the dose of these medicines. (1) |
| Other oral medicines, especially those with a narrow safety margin (e.g., warfarin) | Real, delayed stomach emptying can affect how much of these medicines is absorbed, particularly in the first 8-12 weeks of treatment. | Tell your clinician about all medicines you take; monitoring may be needed. (4) |
Pregnancy, breastfeeding, kidney/liver function, age
Pediatric use
Mounjaro (for type 2 diabetes) is approved in the US for patients 10 years and older; Zepbound's weight-management and OSA uses are approved for adults. (1)
Pregnancy and breastfeeding
Discuss the benefits and risks with your clinician; safety in pregnancy and breastfeeding has not been fully established.
Diabetic retinopathy
Tell your clinician if you have a history of diabetic eye disease, as rapid improvement in blood sugar control can be associated with temporary worsening.
Monitoring
Before starting
- Review personal/family history of MTC or MEN 2.
- Review history of pancreatitis or gallbladder disease.
- Review current oral medicines, especially hormonal contraceptives.
- Discuss contraception planning if using oral contraceptives.
During treatment
- Watch for neck lumps, hoarseness, or swallowing difficulty.
- Watch for severe abdominal pain.
- Stay hydrated, especially if experiencing GI side effects.
- Follow the real, specific 4-week non-oral-contraception guidance around initiation and each dose increase, if applicable.
- Follow your clinician's titration schedule; do not adjust the dose yourself.
Storage
Refrigerate at 36-46°F (2-8°C). If needed, unopened pens may be kept at room temperature (up to 86°F/30°C) for up to 21 days depending on the specific product — check your product's label — then must be discarded. Do not return to the fridge once at room temperature. Do not freeze. Keep the pen in its original carton, protected from light.
Professional information
Clinician-facing context only. Tirzepatide is genuinely authorised in all 5 countries checked for this review, marketed under two distinct brand names for different indications.
United States
Indication: Authorised — real, current FDA approval: Mounjaro (T2DM, including pediatric 10+), Zepbound (weight management; OSA, approved December 2024).
Dose summary: 2.5mg start, titrate to max 15mg weekly.
Renal context: No specific dose adjustment guidance identified in this pass. (1) (2)
United Kingdom
Indication: Authorised — real MHRA approval: September 2022 (T2DM), November 2023 (weight management).
Dose summary: Consistent with US titration.
Renal context: Not itemized. (8)
Australia
Indication: Authorised — real TGA approval for type 2 diabetes.
Dose summary: Consistent with US titration.
Renal context: Not itemized. (9)
New Zealand
Indication: Authorised — real Medsafe approval (22 December 2025) for T2DM and weight management; not yet Pharmac-funded for either use as of this pass.
Dose summary: All 6 real dose strengths approved (2.5-15mg).
Renal context: Not itemized. (10)
Canada
Indication: Authorised — real, direct Health Canada DPD API query confirmed 24 products.
Dose summary: Consistent with US titration.
Renal context: Not itemized. (11)
Hepatic guidance
No specific hepatic dosing guidance identified in the sourced evidence for this pass.
Overdose note
Supportive care; monitor for GI symptoms and hypoglycemia, particularly if combined with insulin/sulfonylureas. (1)
Frequently asked questions
Is tirzepatide a pill or an injection?
It is a real, injection-only medicine — given once weekly by subcutaneous (under-the-skin) injection using a prefilled pen. It has no oral form. (1)
What is the difference between Mounjaro and Zepbound?
Real, important distinction: both contain the same active ingredient, tirzepatide, but Mounjaro is FDA-approved for type 2 diabetes, while Zepbound is FDA-approved for chronic weight management and, since December 2024, for moderate-to-severe obstructive sleep apnea in adults with obesity. (1) (2)
What is the maximum dose of tirzepatide?
The real, current maximum approved dose is 15mg once weekly, reached gradually through a titration schedule starting at 2.5mg. (3)
Does tirzepatide affect birth control pills?
Yes — this is a real, clinically important interaction. Tirzepatide can reduce the absorption of oral contraceptives. The official recommendation is to switch to a non-oral contraceptive method, or add a barrier method, for 4 weeks after starting tirzepatide and for 4 weeks after each dose increase. (4)
What is the mechanism of action of tirzepatide?
Tirzepatide is a dual agonist at GIP and GLP-1 receptors, enhancing glucose-dependent insulin secretion, suppressing glucagon, slowing gastric emptying, and reducing appetite/food intake. (1)
What is the generic name of Tirzepatide?
The generic name is tirzepatide. It is sold under brand names including Mounjaro (type 2 diabetes), Zepbound (weight management and obstructive sleep apnea). (1)
What class of drug is tirzepatide?
Tirzepatide is classed as: Dual GIP and GLP-1 receptor agonist (antidiabetic and anti-obesity agent). (1)
References
- Mounjaro and Zepbound (tirzepatide) — indications, boxed warning, and contraindicationsFDA / Eli Lilly (secondary characterization of current labels) · United States · accessed 2026-07-27 · source 1
- FDA approves Zepbound (tirzepatide) as first prescription medicine for moderate-to-severe OSA in adults with obesityFDA / Eli Lilly press release · United States · accessed 2026-07-27 · source 2
- Mounjaro/tirzepatide dosing and titration scheduleEli Lilly (medical.lilly.com, official manufacturer medical information) · United States · accessed 2026-07-27 · source 3
- Tirzepatide delayed gastric emptying and oral contraceptive interactionFDA label / manufacturer (secondary characterization) · United States · accessed 2026-07-27 · source 4
- Mounjaro Medication Guide — missed dose instructionsEli Lilly (Mounjaro Medication Guide) · United States · accessed 2026-07-27 · source 5
- Mounjaro overdose symptoms and managementFDA label / Eli Lilly (medical.lilly.com) · United States · accessed 2026-07-27 · source 6
- Mounjaro pen storage instructionsEli Lilly (medical.lilly.com) · United States · accessed 2026-07-27 · source 7
- Mounjaro (tirzepatide) UK approval timelineMHRA (secondary characterization) · United Kingdom · accessed 2026-07-27 · source 8
- Mounjaro (tirzepatide) — TGA AusPMD approval summaryTGA (Australia) · Australia · accessed 2026-07-27 · source 9
- Mounjaro (tirzepatide) — New Zealand Data SheetMedsafe (New Zealand) · New Zealand · accessed 2026-07-27 · source 10
- DPD active-ingredient query for tirzepatide (24 real products confirmed)Health Canada DPD, public API · Canada · accessed 2026-07-27 · source 11
Brand names by country
Single-ingredient tirzepatide names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Mounjaro7.5 mg/.5mL, 20.8 mg/mL, 12.5 mg/.5mL, 12.5 mg/mL, 8.33 mg/mL, 10 mg/.5mL, 5 mg/.5mL, 4.17 mg/mL · a-s medication solutions
- Zepbound20.8 mg/mL, 25 mg/mL, 2.5 mg/.5mL, 12.5 mg/.5mL, 7.5 mg/.5mL, 4.17 mg/mL, 15 mg/.5mL, 10 mg/.5mL · eli lilly and company
United Kingdom
- Mounjaro (8)real mhra approved sept2022 t2dm nov2023 weight management · 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg · Eli Lilly and Company
Canada
- Mounjaro / Tirzepatide (11)real direct dpd api 24 products confirmed · 5 mg, 7.5 mg, 10 mg, and others · Eli Lilly Canada
Australia
- Mounjaro (9)real tga approved t2dm confirmed · 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg · Eli Lilly Australia Pty Ltd
New Zealand
- Mounjaro (10)real medsafe approved 22dec2025 t2dm and weight management not yet pharmac funded · 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg · Eli Lilly (NZ)