Tirzepatide Dosage Chart and Complete Evidence Guide

The tirzepatide peptide is the second-generation GLP-1-class drug that broke the weight-loss ceiling. By adding GIP-receptor activation to the GLP-1 pharmacology established by semaglutide, the tirzepatide peptide produced roughly 50% greater weight loss in head-to-head trials, and became the fastest drug launch in pharmaceutical history along the way. Tirzepatide for weight loss is now the most-prescribed dual-agonist in this class.

What tirzepatide is#

Tirzepatide is a synthetic 39-amino-acid peptide engineered to activate two receptors in the same molecule: glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). The structure is modified from a native GIP backbone with a C20 fatty-acid tail that binds albumin and extends the half-life to approximately five days, enabling once-weekly subcutaneous dosing.

Studies have shown GLP-1 agonism suppresses appetite, slows gastric emptying, and stimulates glucose-dependent insulin release. GIP agonism augments insulin secretion and has been shown to have independent effects on adipose tissue. The combination produces larger average weight loss than either pathway alone, a finding confirmed across the Phase 3 SURMOUNT and SURPASS programmes.

Tirzepatide: one molecule, two incretin receptors

The efficacy data#

Obesity: SURMOUNT-1. SURMOUNT-1 (Jastreboff et al., NEJM 2022, n=2,539) randomised adults with obesity 1:1:1:1 to tirzepatide 5 mg, 10 mg, 15 mg or placebo for 72 weeks.

It reported the result two ways, and almost nobody says which one they are quoting.

Dose	Treatment-regimen estimand	Efficacy estimand
5 mg	−15.0%	−16.0%
10 mg	−19.5%	−21.4%
15 mg	−20.9%	−22.5%
Placebo	−3.1%	−2.4%

The treatment-regimen estimand is intention-to-treat: it counts everyone randomised, including those who stopped. The efficacy estimand conditions on staying on the drug as assigned.

The number in general circulation, including in Klarovel's own earlier version of this page, is 22.5%. That is the efficacy estimand. The intention-to-treat figure for the same dose in the same trial is 20.9%.

Neither is wrong, and the gap is not large. What matters is which question each answers. If you are asking what happened to people prescribed tirzepatide, 20.9% is the number. If you are asking what happens to someone who takes it as directed for 72 weeks, 22.5% is the number. The distinction is load-bearing here because tirzepatide is a continuous-use drug and a meaningful number of trial participants stopped taking it.

Discontinuation for adverse events in SURMOUNT-1 ran 4.3% at 5 mg, 7.1% at 10 mg, 6.2% at 15 mg, against 2.6% on placebo. Note that it does not climb steadily with dose: the peak is the 10 mg arm, not the 15 mg one. Most gastrointestinal side effects concentrate during escalation rather than at the maintenance dose, which is a better explanation of that shape than dose alone.

Obesity, head-to-head vs semaglutide: SURMOUNT-5. The NEJM head-to-head trial (2025) directly compared tirzepatide and semaglutide in obesity at their highest approved doses. Primary endpoint at 72 weeks: -20.2% with tirzepatide vs -13.7% with semaglutide. The waist-circumference effect was similarly separated: -18.4 cm vs -13.0 cm.

Type-2 diabetes: SURPASS programme. Across the SURPASS trials, tirzepatide consistently outperformed semaglutide, insulin degludec, and insulin glargine on HbA1c reduction. SURPASS-2 specifically compared tirzepatide 15 mg against semaglutide 1 mg weekly in adults with type-2 diabetes, and tirzepatide was superior across all doses tested.

Tirzepatide dosage chart: every approved strength#

The tirzepatide dosage chart below is the full escalation schedule. Tirzepatide dosing follows it strictly to minimise gastrointestinal side effects, and the standard tirzepatide dosage steps below come directly from the SURMOUNT and SURPASS protocols:

Phase	Weekly dose	Duration	Tested as its own SURMOUNT-1 arm?	Outcome at 72 weeks (ITT)
Start	2.5 mg	Weeks 1–4	No. Escalation step only	no arm
Step 1	5 mg	Weeks 5–8	Yes (n=630)	−15.0%
Step 2	7.5 mg	Weeks 9–12	No. Escalation step only	no arm
Step 3	10 mg	Weeks 13–16	Yes (n=636)	−19.5%
Step 4	12.5 mg	Weeks 17–20	No. Escalation step only	no arm
Target	15 mg	Weeks 21+	Yes (n=630)	−20.9%

The Zepbound dosage chart is the same chart. Zepbound and Mounjaro are both tirzepatide, licensed in the same six strengths on the same four-week escalation, so a zepbound dose chart and a Mounjaro one differ only in the indication printed on the box. Anything below about the ladder, the trial arms or the units applies to both names.

Three of the six approved dose strengths were never tested as maintenance doses. SURMOUNT-1 randomised to 5, 10 and 15 mg only. Everyone started at 2.5 mg and stepped up by 2.5 mg every four weeks to reach their assigned arm, so 2.5, 7.5 and 12.5 mg exist in the label as waypoints on the way somewhere else, not as studied destinations.

That is not a criticism of the label. Escalation steps are there for tolerability, and the trial design is standard. It does mean that someone who stops at 7.5 mg because it suits them is sitting on a dose with no dedicated efficacy readout, interpolating between the 5 mg and 10 mg arms. Worth knowing, and not stated anywhere else in this search result.

Not every patient titrates to 15 mg. Many achieve clinically meaningful weight loss at 5 mg or 10 mg and stay there. The correct target dose is the lowest dose that produces the desired response with tolerable side effects. The Klarovel titration calculator builds a customised week-by-week schedule for a chosen target dose.

Reconstitution for research-grade vials: a typical 10 mg tirzepatide vial reconstituted with 2 mL of bacteriostatic water yields 5 mg/mL. A 5 mg weekly dose equals 1 mL = 100 syringe units. The Klarovel tirzepatide calculator handles any vial size and target dose combination.

Tirzepatide dosing for weight loss in units#

Every U-100 insulin syringe marks 100 units per mL, on 0.3, 0.5 and 1 mL barrels alike, so one number converts the whole ladder. At the 5 mg/mL reference above, 1 unit is 0.05 mg.

Weekly dose	Volume at 5 mg/mL	Syringe units	Fits a 1 mL barrel?
2.5 mg	0.5 mL	50 units	Yes
5 mg	1.0 mL	100 units	Exactly full
7.5 mg	1.5 mL	150 units	No
10 mg	2.0 mL	200 units	No
12.5 mg	2.5 mL	250 units	No
15 mg	3.0 mL	300 units	No

The last column is the part most dosage charts leave out. At 5 mg/mL only the two lowest steps fit a standard 1 mL insulin syringe, so anyone reading tirzepatide dosing for weight loss in units past the 5 mg step is either splitting the dose across two draws or working from a more concentrated vial. Higher concentration shrinks the volume and the unit count in exact proportion: at 10 mg/mL every figure in the units column halves.

That is arithmetic, not a dose recommendation. The strengths themselves come from the label ladder above, and the tirzepatide calculator does the conversion for any vial size and diluent volume.

Vial, pen or KwikPen: the presentations are not interchangeable arithmetic#

This is the part every guide to tirzepatide skips, and it is the part that decides whether someone draws the right volume.

Branded tirzepatide ships in four presentations, and per the Zepbound prescribing information they do not share a concentration.

Presentation	Volume	Doses	Concentration
Single-dose pen	0.5 mL	1	Fixed per strength
Single-dose vial	0.5 mL	1	Fixed per strength
Multi-dose vial	2.4 mL	4	Varies by strength
Single-patient-use KwikPen	2.4 mL	4	Varies by strength

And within the multi-dose presentations, the concentration changes with every strength:

Dose per injection	Total per container	Concentration
2.5 mg / 0.6 mL	10 mg / 2.4 mL	4.17 mg/mL
5 mg / 0.6 mL	20 mg / 2.4 mL	8.33 mg/mL
7.5 mg / 0.6 mL	30 mg / 2.4 mL	12.5 mg/mL
10 mg / 0.6 mL	40 mg / 2.4 mL	16.7 mg/mL
12.5 mg / 0.6 mL	50 mg / 2.4 mL	20.8 mg/mL
15 mg / 0.6 mL	60 mg / 2.4 mL	25 mg/mL

The injected volume is always 0.6 mL. The concentration does the work. From 2.5 mg to 15 mg the solution is six times stronger, which is why a dose cannot be estimated by eye and why the same volume means something different in each container.

Three practical consequences, none of them widely stated:

• Branded presentations are ready-to-use solution, not powder. They are not reconstituted. Research-grade tirzepatide, covered further down, is lyophilised and does need reconstitution, and conflating the two is the most common arithmetic error in this area.
• Multi-dose presentations contain preservatives, single-dose ones do not. The multi-dose vial and KwikPen include benzyl alcohol and phenol; the single-dose pen and vial contain neither. That matters for anyone with a benzyl alcohol sensitivity.
• Do not decant a KwikPen into a syringe. The device blocks a full fifth dose by design and the manufacturer instructs against transferring the residual volume. The leftover is priming volume, not a bonus dose.

Efficacy was established in SURMOUNT-1 and SURMOUNT-2 using the single-dose pen. The vial carries the same formulation, the same excipient concentrations and the same strengths; the difference is the delivery device, not the drug.

For the mg-to-syringe-unit conversion on any concentration, the Klarovel tirzepatide calculator does the arithmetic.

There is no tirzepatide pill, and Zepbound is not a GLP-1 drug#

Two questions that dominate the search volume around this compound, both with short answers that are worth giving straight.

There is no oral tirzepatide. Not approved, not available, not in late-stage trials as a tablet. Tirzepatide is a 39-amino-acid peptide, and peptides of that size are degraded by digestive enzymes and absorb poorly across the gut wall. Oral semaglutide exists (Rybelsus) because it is co-formulated with an absorption enhancer, SNAC, and even then it requires a much larger dose and strict fasting conditions. Nothing equivalent has been approved for tirzepatide. Searches for a tirzepatide pill or tablet are, as of 2026, looking for something that does not exist, and any vendor offering one is not selling tirzepatide.

Zepbound is not a GLP-1 agonist. It is a dual GIP and GLP-1 agonist. The distinction is the whole reason the compound outperforms semaglutide. GLP-1 receptor agonism drives satiety and slows gastric emptying; adding GIP receptor agonism appears to improve insulin sensitivity and fat handling on top of that. Calling it a GLP-1 is not exactly wrong, since GLP-1 agonism is half of what it does, but it is imprecise in a way that obscures why the trial numbers differ.

Side effects and tolerability#

Tirzepatide side effects in Phase 3 trials cluster heavily on the gastrointestinal axis, and the gastrointestinal events below dominate the tirzepatide side effects profile:

• Nausea (~29% of participants)
• Diarrhoea (~23%)
• Vomiting (~13%)
• Constipation (~17%)
• Decreased appetite (~12%)

Most are mild to moderate, dose-related, and concentrate during the escalation phase. Slower titration and adequate hydration mitigate intensity. Discontinuation rates due to adverse events run 6–7% in Phase 3 trials, lower than many oral diabetes medications.

Less common but meaningful signals:

• Hypoglycaemia when combined with insulin or sulfonylureas (class effect)
• Pancreatitis (class warning across GLP-1 drugs; incidence is low)
• Gallbladder disease, associated with a slightly elevated risk as a class effect
• Thyroid C-cell tumours observed in rodents; not confirmed in humans but informs the absolute contraindication for patients with personal or family history of medullary thyroid carcinoma or MEN 2

Regulatory status and access#

Tirzepatide is FDA-approved as:

• Mounjaro (2022), adults with type-2 diabetes
• Zepbound (2023), chronic weight management in adults with obesity or overweight with weight-related comorbidities

EMA-approved under the Mounjaro brand (type-2 diabetes and obesity). Approved and marketed in Norway via DMP under the Mounjaro brand name; Zepbound is not separately distributed.

Insurance coverage and reimbursement status in Norway are evolving. As of April 2026, tirzepatide for weight loss is generally not reimbursed under blue-resept (the Norwegian public reimbursement scheme) but may be prescribed on white resept at full out-of-pocket cost. For type-2 diabetes, reimbursement rules depend on individual clinical criteria. Klarovel does not sell, source or fulfil tirzepatide; every dose figure on this page is read from the engine's own tables rather than hand-authored, and our research positioning and disclosures set out how that works.

Tirzepatide vs semaglutide vs retatrutide#

The receptor-count pattern across the class:

Drug	Receptors	Weight loss	Timepoint
Semaglutide 2.4 mg	GLP-1	14.9%	68 weeks
Tirzepatide 15 mg	GIP + GLP-1	20.9%	72 weeks
Retatrutide 12 mg	GIP + GLP-1 + glucagon	23.7%	68 weeks

These are intention-to-treat figures, deliberately. Semaglutide's 14.9% from STEP 1 is its primary treatment-policy estimand, so pairing it with tirzepatide's 22.5% efficacy estimand, as most comparisons do, flatters tirzepatide by roughly 1.6 percentage points on presentation alone. Compared like with like the gap is still decisive, and SURMOUNT-5 settled it head-to-head anyway, but a cross-trial table is only honest when the estimands match.

Tirzepatide's position is as the FDA- and EMA-approved ceiling of the class. Semaglutide remains the first-line for most patients starting therapy. Retatrutide is still unapproved and not expected to be available until 2027–2028.

For the full head-to-head comparison with semaglutide, see semaglutide vs tirzepatide.

Direct comparisons: AOD-9604 vs tirzepatide, Cagrilintide vs tirzepatide, Tirzepatide vs retatrutide.

Practical considerations#

Three things matter for anyone considering a tirzepatide protocol:

1. Titrate slowly. The gastrointestinal side-effect signal concentrates during dose escalation. Staying at each step for the full 4 weeks before increasing reduces the risk of intolerable nausea. The titration calculator builds the schedule.
2. Bloodwork before and during. HbA1c, lipid panel, and TSH are minimum baseline. Repeat at 12 and 24 weeks to confirm metabolic response and screen for thyroid changes.
3. Klarovel does not sell, source, or fulfil peptides. How you obtain research-grade tirzepatide is outside the platform. For protocol planning, the intake questionnaire screens for contraindications and the peptide calculator handles the dose math.

Tirzepatide is the most important incremental step the GLP-1 class has made since semaglutide. For a well-screened, well-titrated patient, the efficacy is real and the side-effect profile is manageable. The rest is discipline on the escalation schedule and honesty about the data. For how tirzepatide sits alongside the rest of the field, see the broader guide to peptides for weight loss.