Compound record · Metabolic (incretin-based)

Tirzepatide

Also Mounjaro · Zepbound · LY3298176 · Tirz

Dual GIP/GLP-1 receptor agonist

Metabolic (incretin-based)Evidence · StrongApproved medicine (for specific indications)

Once-weekly dual incretin with the largest weight loss among authorised medicines

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Record reviewed 1 September 2026 · 6 references

In the AERVYN range

1 pen carries Tirzepatide

Single-compound pen
Tirzepatide
Peptide pen · 30 mg / 3 mL
£320 · In stock

Class: Dual GIP/GLP-1 receptor agonist
Route: Weekly subcutaneous injection
Trial participants: > 15,000 adults exposed across 14 completed phase 3 studies
Licensed weight loss: ≈ 21% mean at 72 weeks (SURMOUNT-1, 15 mg)
Prescription: Required in UK, US, EU, AU, CA

01 Overview

What Tirzepatide is

Summary

Tirzepatide is a once-weekly dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist authorised for type 2 diabetes and for chronic weight management (Mounjaro in the UK, EU and Australia; Zepbound in the US and Canada). In SURMOUNT-1 the 15 mg dose produced a mean 20.9% body-weight reduction at 72 weeks, and the 2025 SURMOUNT-5 head-to-head trial reported greater weight loss than semaglutide 2.4 mg.

Mechanism

Activates both GIP and GLP-1 receptors: enhances glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying and reduces appetite and food intake through central pathways. GIP receptor activity appears to add to the appetite and energy-balance effects and may improve gastrointestinal tolerability of GLP-1 receptor activation.

Routes studiedSubcutaneous injection

Anti-dopingNot prohibited

02 Evidence by goal

What has been shown, for which goal

Grades follow one scale across the site. Strong overall means: multiple large randomised controlled trials or regulatory approval for this use.

Weight management
Strong
In SURMOUNT-1 (n = 2,539), 5, 10 and 15 mg weekly produced mean weight reductions of 15.0%, 19.5% and 20.9% at 72 weeks versus 3.1% with placebo. In SURMOUNT-5 (n = 751) tirzepatide produced 20.2% weight loss versus 13.7% with semaglutide 2.4 mg at 72 weeks.
Fat loss / body composition
Moderate
In the SURMOUNT-1 DXA sub-study, total fat mass fell by approximately a third (33.9% versus 8.2% with placebo) and roughly three times as much fat as lean mass was lost; lean mass still declined, so resistance training and adequate protein intake are usually advised.
Longevity
Moderate
SURPASS-CVOT (n ≈ 13,300, type 2 diabetes with cardiovascular disease) showed tirzepatide was non-inferior to dulaglutide for major adverse cardiovascular events with lower all-cause mortality; SUMMIT (n = 731) reduced worsening heart failure in obesity-related HFpEF. There is no placebo-controlled cardiovascular-outcome trial yet (SURMOUNT-MMO is ongoing).
Sleep
Moderate
In SURMOUNT-OSA (two trials, n = 469) tirzepatide reduced the apnoea–hypopnoea index by roughly 25–29 events per hour versus about 5 with placebo at 52 weeks in adults with obesity and moderate-to-severe obstructive sleep apnoea, and is FDA-approved for that indication. There is no evidence for sleep quality in people without sleep apnoea.

03 Regulatory status

Where it is authorised, and for what

Status is recorded per jurisdiction from regulator sources and reviewed by hand. It is never inferred from another region's decision.

United Kingdom

Authorised

Authorised (MHRA) for type 2 diabetes and weight management (Mounjaro); prescription-only.

Mounjaro is licensed for type 2 diabetes and, since November 2023, for weight management in adults with BMI ≥ 30, or ≥ 27 with a weight-related comorbidity. NICE TA1026 (December 2024) recommends it for adults with BMI ≥ 35 and at least one weight-related comorbidity, with a phased NHS roll-out that began in primary care in June 2025. Prescription-only medicine.

StatusAuthorised

Status last reviewed1 September 2026

SourceOur maintained database — never inferred

04 Dosing research

What the evidence says about exposure

Published human studies and the doses, routes and durations they used — reported as research information, not a recommendation.

Research information — not a recommendation. These are the exposures used in published human studies, reported so you can see what has been tested. They are not dosing instructions and do not apply to any individual.

Study 01

SURMOUNT-1 — once-weekly tirzepatide in adults with obesity

Jastreboff AM et al., N Engl J Med 2022;387:205–216 · Source

Phase 32022

Design: Randomised, double-blind, placebo-controlled
Population: Adults without diabetes with BMI ≥ 30, or ≥ 27 with ≥ 1 weight-related complication
Participants: n = 2,539
Duration: 72 weeks
Route: Subcutaneous injection

Doses studied: Started at 2.5 mg once weekly and increased by 2.5 mg every 4 weeks to maintenance doses of 5, 10 or 15 mg once weekly
Outcome at this exposure: Mean weight change −15.0% (5 mg), −19.5% (10 mg) and −20.9% (15 mg) vs −3.1% with placebo; 85–91% lost ≥ 5% vs 35%.
Adverse events observed: Gastrointestinal events most common (nausea in roughly 25–33% vs 9.5%; diarrhoea, vomiting, constipation), mostly mild-to-moderate and concentrated during dose escalation; discontinuation for adverse events 4.3–7.1% vs 2.6%; hair loss reported in around 5% vs 1%.

Study 02

SURMOUNT-2 — tirzepatide in adults with obesity and type 2 diabetes

Garvey WT et al., Lancet 2023;402:613–626 · Source

Phase 32023

Design: Randomised, double-blind, placebo-controlled
Population: Adults with type 2 diabetes and BMI ≥ 27
Participants: n = 938
Duration: 72 weeks
Route: Subcutaneous injection

Doses studied: 10 mg or 15 mg once weekly after escalation from 2.5 mg in 2.5 mg steps every 4 weeks
Outcome at this exposure: Mean weight change −12.8% (10 mg) and −14.7% (15 mg) vs −3.2% with placebo; HbA1c fell by approximately 2.1 percentage points vs 0.5 with placebo.
Adverse events observed: Gastrointestinal events most common and mostly mild-to-moderate; discontinuation for adverse events approximately 4–7% vs 4%; hypoglycaemia was uncommon in the absence of insulin or sulfonylureas.

Study 03

SURMOUNT-5 — tirzepatide versus semaglutide in adults with obesity

Aronne LJ et al., N Engl J Med 2025;393:26–36 · Source

Phase 3b2025

Design: Randomised, open-label, active-controlled
Population: Adults with obesity (BMI ≥ 30, or ≥ 27 with a weight-related complication) without type 2 diabetes
Participants: n = 751
Duration: 72 weeks
Route: Subcutaneous injection

Doses studied: Maximum tolerated dose of tirzepatide (10 or 15 mg once weekly) vs maximum tolerated dose of semaglutide (1.7 or 2.4 mg once weekly)
Outcome at this exposure: Mean weight change −20.2% with tirzepatide vs −13.7% with semaglutide (difference −6.5 percentage points); waist circumference −18.4 cm vs −13.0 cm.
Adverse events observed: Gastrointestinal events most common in both groups, mostly mild-to-moderate and occurring mainly during dose escalation; discontinuation for adverse events 6.1% with tirzepatide vs 8.0% with semaglutide.

05 Safety

Adverse effects and contraindications

Common effects seen in trials or reports, serious effects that warrant urgent review, and conditions under which use is not appropriate or needs assessment.

Common adverse effects

Nausea
Diarrhoea
Vomiting
Constipation
Dyspepsia and abdominal pain
Reduced appetite and early satiety
Injection-site reactions
Fatigue
Dizziness and low blood pressure symptoms
Hair loss (reported in around 5% in weight-management trials)

Serious adverse effects

Acute pancreatitis (including necrotising and fatal post-marketing reports)
Gallbladder disease (gallstones, cholecystitis)
Acute kidney injury from dehydration
Severe hypoglycaemia when combined with insulin or sulfonylureas
Worsening of diabetic retinopathy
Increased heart rate
Severe allergic reactions including anaphylaxis and angioedema (rare)
Aspiration during anaesthesia due to retained stomach contents (label warning)

Contraindications

Personal or family history of medullary thyroid cancer or MEN2Do not use
The US label contraindicates use with a personal or family history of medullary thyroid carcinoma or MEN2 (boxed warning based on rodent thyroid C-cell tumours); UK labelling carries a thyroid warning.
Previous pancreatitisDo not use
Not studied in people with a history of pancreatitis; labels advise caution or alternative treatment. Acute pancreatitis, including necrotising and fatal cases, has been reported post-marketing.
Gastroparesis (slow stomach emptying)Do not use
Not studied in severe gastroparesis and expected to slow gastric emptying further; labels advise against use.
Thyroid diseaseCaution
Thyroid disease itself is not a contraindication, but any thyroid cancer history must be clarified; levothyroxine absorption can change as gastric emptying slows.
Pancreatic diseaseCaution
Pancreatic disease warrants specialist assessment before considering any incretin medicine.
Gallbladder diseaseCaution
Cholelithiasis and cholecystitis occur more often with rapid weight loss and were more frequent than placebo in trials.
DiabetesCaution
Hypoglycaemia risk rises with insulin or sulfonylureas, whose doses are usually reduced; type 1 diabetes is outside the licence.
Diabetic retinopathy (eye disease)Caution
Rapid improvement in glucose control has been associated with temporary worsening of diabetic retinopathy; labels advise close monitoring.
Kidney diseaseCaution
Acute kidney injury has been reported, usually with dehydration from vomiting or diarrhoea; hydration should be maintained.
Gastrointestinal diseaseCaution
Not studied in severe gastrointestinal disease; slowed gastric emptying may worsen symptoms.
Mental health conditionCaution
Weight-management labelling advises monitoring for depression or suicidal thoughts; discuss any mental-health history.
Current or previous eating disorderCaution
Appetite-suppressing medicines require specialist assessment where there is a current or previous eating disorder.
Cardiovascular diseaseCaution
Resting heart rate rises by a few beats per minute on average, and hypotension-related events were reported in weight-management trials; arrhythmia and heart-failure history should be reviewed.

Do not use = should not be used · Caution = needs assessment

06 Interactions

Medicine classes that need review

Grouped by how seriously the combination should be taken. Class labels match the medicines questionnaire in the assessment.

Major
Moderate
Minor

Major

Combination should be reviewed by a prescriber before use.

Insulin
Lantus, NovoRapid, Humalog, Tresiba
Combined use increases hypoglycaemia risk; labels recommend a stepwise insulin reduction with glucose self-monitoring.
Sulfonylurea
Gliclazide, glimepiride, glipizide
Combined use increases hypoglycaemia risk; sulfonylurea dose reduction is usually considered.
GLP-1 / incretin medicine
Ozempic, Wegovy, Mounjaro, Saxenda
Should not be combined with another GLP-1 or GIP/GLP-1 medicine — duplicate mechanism with no safety data.

Moderate

Monitoring or dose review is usually advised.

Oral contraceptive
Combined pill, progestogen-only pill
Tirzepatide reduces oral-contraceptive exposure (ethinylestradiol peak concentration fell by 59% and total exposure by 20% in a single-dose study). Labels advise switching to a non-oral method or adding a barrier method for 4 weeks after starting and for 4 weeks after each dose increase.
Anticoagulant (blood thinner)
Warfarin, apixaban, rivaroxaban
Delayed gastric emptying can alter absorption; closer INR monitoring is prudent when starting or changing dose alongside warfarin.
Thyroid hormone
Levothyroxine, liothyronine
Levothyroxine exposure may change with slowed gastric emptying; thyroid function should be monitored.
Narrow-therapeutic-index medicine
Lithium, digoxin, ciclosporin
Medicines that depend on rapid absorption or have a narrow therapeutic window may need closer monitoring during dose escalation.

Minor

Generally compatible; awareness is sufficient.

Blood pressure medicine
Ramipril, amlodipine, losartan
Weight loss lowers blood pressure and hypotension-related events were reported in weight-management trials; blood-pressure medicines may need review.
Other glucose-lowering medicine
Metformin, SGLT2 inhibitors, DPP-4 inhibitors
Generally compatible with metformin and SGLT2 inhibitors; glucose monitoring advised when combined.

07 Pregnancy & breastfeeding

Status in pregnancy

Not recommended

Not recommended in pregnancy or while breastfeeding; animal studies showed reproductive toxicity. UK labelling advises stopping at least one month before a planned pregnancy because of the long half-life, and notes that oral-contraceptive effectiveness may be reduced.

08 Monitoring

What is usually monitored

Parameters that trials and product information track. A clinician decides what applies to an individual.

01Weight and BMI trend against the licensed eligibility criteria (labels ask for a review if < 5% is lost after 6 months on the highest tolerated dose)
02Gastrointestinal tolerability at every 2.5 mg dose step
03Contraception method for 4 weeks after starting and after each dose increase
04Blood glucose if on insulin or sulfonylureas
05Hydration and kidney function during vomiting or diarrhoea
06Heart rate, blood pressure and mood
07Muscle mass and protein intake during rapid weight loss

09 Combinations

What is known about combining it

Notes on pairing with other compounds in the directory: whether the combination has been studied in people, and where mechanisms overlap.

Semaglutide
No human studies
Overlap · Both are incretin-based appetite and glucose medicines acting on GLP-1 receptors.
Combining two incretin medicines duplicates mechanism, has no safety data and is outside every licence.
Liraglutide
No human studies
Overlap · Both act on GLP-1 receptors.
Duplicate mechanism — two incretin medicines should not be combined.
Retatrutide
No human studies
Overlap · Retatrutide already includes GIP and GLP-1 receptor activity.
No rationale or data for combining; retatrutide is itself unauthorised.
Cagrilintide
No human studies
Overlap · Both reduce appetite and slow gastric emptying.
Cagrilintide has only been studied with semaglutide (CagriSema); there are no human data on combining it with tirzepatide.
Survodutide
No human studies
Overlap · Both include GLP-1 receptor activity.
Duplicate incretin mechanism with no human data; survodutide is investigational.
CJC-1295
No human studies
No human studies of incretin medicines combined with growth-hormone secretagogues.
Ipamorelin
No human studies
No human studies of incretin medicines combined with growth-hormone secretagogues.
BPC-157
No human studies
No human data on this combination; BPC-157 itself lacks human efficacy data.

Discuss any proposed combination with a qualified healthcare professional.

10 Source considerations

Supply, quality and legitimacy

How the compound reaches people in practice, and what that means for product quality.

01Prescription-only medicine in every major jurisdiction — legitimate supply requires a prescription from a licensed prescriber.
02The MHRA and FDA have issued warnings about counterfeit Mounjaro pens and unregulated online sellers.
03Compounded or 'research-grade' tirzepatide vials are not the authorised product; since the FDA declared the shortage resolved in December 2024, routine compounding of copies is not permitted in the US.

11 Questions for your clinician

Take these to your appointment

Specific to this compound. The personal assessment adds questions drawn from your own history and medicines.

01Do I meet the licensed eligibility criteria (BMI and weight-related conditions) in my country?
02How will my other medicines — especially diabetes medicines, blood thinners or the contraceptive pill — be adjusted?
03What is the plan for the 2.5 mg dose steps and for managing nausea or constipation?
04How will we protect muscle mass while I lose weight?
05What happens when treatment stops, and is there a maintenance plan?

The personal assessment tailors this list to your responses.

12 Alternatives

Compounds with stronger evidence or firmer regulatory footing

Listed for overlapping goals. Whether any is appropriate depends on your history — the assessment maps that for you.

13 References

Sources behind this record

Regulator documents and peer-reviewed publications used to derive every grade and statement above.

The Peptide Checkup provides educational information and a structured summary of published research and regulatory status. It is not medical advice, does not diagnose or treat any condition, and does not replace a consultation with a qualified healthcare professional.

Personal assessment

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Seven minutes of structured questions about your goal, history and medicines, mapped against this record by a deterministic, clinician-reviewable rules engine. The report tells you when not to buy.

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