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Comparison · sourced side by side

Retatrutide vs Tirzepatide

Nobody has ever tested retatrutide against tirzepatide head to head. Each one went up against a dummy treatment on its own, in different people, for different lengths of time. Their numbers come from separate experiments, so subtracting one from the other tells you nothing. Below, each record stands on its own.

Human trial FDA label

What matters first

Head-to-head evidence
No direct trial
Retatrutide record
Human trial; 1 sourced dose row
Tirzepatide record
FDA label; 2 sourced dose rows

Is there a head-to-head trial?

No trial has ever compared retatrutide and tirzepatide head to head. Putting separate trials side by side can make a false comparison. The trials may include different people, run for different lengths of time, and measure at different moments. The gap between their numbers is not a measured difference between the drugs.

Each result can still be read on its own. Both appear below with their own citations, but not on one shared chart.

RetatrutideHuman trial

48-week phase 2 dose-finding trial · 338 participants · 48 weeks

  • 1 mg — -8.7% mean weight change
  • 4 mg — -17.1% mean weight change
  • 8 mg — -22.8% mean weight change
  • 12 mg — -24.2% mean weight change
  • placebo — -2.1%

At 48 weeks, the groups lost 8.7% of their starting weight at 1 mg and 24.2% at 12 mg, on average. The 4 mg and 8 mg groups lost 17.1% and 22.8%. The placebo group lost 2.1%.

The full retatrutide record →
TirzepatideFDA label

Approved with a prescribing label; its dosing schedule and reaction profile are label-sourced and shown in the table below.

The full tirzepatide record →

Side by side

Every row is read from the two records, and every clinical figure carries its own citation. Where a value does not exist, the row says so instead of guessing one.

Retatrutide and Tirzepatide side by side: drug class, brand names, FDA approval, strongest source, dosing, half-life, boxed warning, reported reactions and typical vial sizes
PropertyRetatrutideTirzepatide
Drug classGIP/GLP-1/glucagon triple receptor agonist (investigational)GIP/GLP-1 dual receptor agonist
Brand namesNone — no approved productZepbound, Mounjaro
FDA approvalNot approved — investigationalApproved
Strongest sourceHuman trialFDA label
Dosing1–12 mg once weekly5–15 mg once weekly (5, 10, or 15 mg)
Half-lifeNot recorded≈ 5 days
Boxed warningNone on recordRisk of thyroid C-cell tumors
Reactions on record615
Typical vial sizes10 mg · 20 mg · 30 mg5 mg · 10 mg · 15 mg · 30 mg · 60 mg

Every clinical value above is cited in the Sources list. Reference information, not a recommendation.

4Comparison detailsMechanism, side effects, regulatory context, and source records

How they work differently

Retatrutide is a gip/glp-1/glucagon triple receptor agonist. Tirzepatide is a gip/glp-1 dual receptor agonist. They switch on different signals in the body. That can change both benefits and side effects. Sharing one target does not make two drugs interchangeable.

More targets do not guarantee a better result. They change both the effect and the side-effect pattern. A clinician weighs those tradeoffs for each person.

Side effects compared

Side effects below come from each compound’s own page, grouped by whether both records list them. A side effect on one list only means the other record does not carry it — not that it never happens.

On both records
  • Nausea
  • Diarrhea
  • Vomiting
  • Constipation
  • Decreased appetite
Recorded for Retatrutide only
  • Increased heart rate
Recorded for Tirzepatide only
  • Abdominal pain
  • Dyspepsia (indigestion)
  • reactions where injected
  • Fatigue
  • Acute pancreatitis
  • Gallbladder disease (cholelithiasis)
  • Hypoglycemia (with insulin or a sulfonylurea)
  • Acute kidney injury (from dehydration)
  • Diabetic retinopathy complications
  • Severe hypersensitivity reactions
Full retatrutide side-effect record

Frequencies, serious reactions and the source for each.

Full tirzepatide side-effect record

Frequencies, serious reactions and the source for each.

Regulatory status compared

Retatrutide

FDA has not approved retatrutide.

It is still in trials and has no dosing label. Any product sold today is unapproved. The doses here describe study groups, not advice.

Tirzepatide

FDA-approved as branded pens.

Compounded tirzepatide now faces tight limits. FDA declared the shortage over in late 2024. It has proposed dropping tirzepatide from the 503B bulks list.

That leaves one narrow lane: 503A compounding for a named patient with a documented clinical need.

The full regulatory tracker →

Keep reading

A comparison is a summary of two records. These are the pages themselves, plus the tools and schedules the rows above are read from.

What the sources say about tirzepatide, beyond retatrutide vs tirzepatide

15 sourced tirzepatide reactions, on its own page, separate from retatrutide vs tirzepatide.

The retatrutide page behind retatrutide vs tirzepatide

Retatrutide has published human trial data, separate from retatrutide vs tirzepatide.

The retatrutide calculator behind retatrutide vs tirzepatide

The retatrutide vial presets are 1 mL and 2 mL of water. They belong to this tool, not to the retatrutide vs tirzepatide page.

Convert a tirzepatide amount to units, beyond retatrutide vs tirzepatide

U-100, U-50 and U-40 barrels for tirzepatide, computed independently of retatrutide vs tirzepatide.

Every tirzepatide step, outside retatrutide vs tirzepatide

2 sourced tirzepatide values, each traceable without going via retatrutide vs tirzepatide.

The retatrutide schedule that retatrutide vs tirzepatide summarizes

The whole retatrutide trial program, in full past retatrutide vs tirzepatide.

The draw arithmetic behind retatrutide vs tirzepatide

Vial strength and water volume in and the exact mark out, with retatrutide vs tirzepatide as context

Where both drugs in retatrutide vs tirzepatide stand with the regulator

Approval status, proceedings and the date attached to each, with retatrutide vs tirzepatide as one example

All the comparison pages, including retatrutide vs tirzepatide

Dosing, source strength and reactions, one table per pair, including retatrutide vs tirzepatide

The sourcing rules that shape retatrutide vs tirzepatide

Why a label band and a trial percentage are never averaged, with retatrutide vs tirzepatide as context

Common questions

Which is more effective, retatrutide or tirzepatide?

Nobody knows, because nobody has tested them against each other. Each was tested separately against a dummy treatment, and those two results cannot be subtracted to give a difference.

Can these two be compared using their separate trial results?

Not reliably. Separate trials can include different people, run for different lengths of time, and measure different things. Only a head-to-head trial measures the difference.

Are the side-effect profiles the same?

They overlap a lot — 5 side effects appear on both records, mostly stomach-related. The lists also differ. Evidence from an approved label is stronger than an early trial report.

Is either one approved by the FDA?

Tirzepatide is FDA-approved and has a prescribing label. Retatrutide is still experimental, has no approved label, and anything sold today is unapproved.

Does a newer compound mean a better one?

No. A newer drug often has less evidence, a shorter safety record, and no approved label. The strength of the evidence above is more useful than age alone.

Can someone switch between them?

A clinician decides that based on the reason for treatment, the current dose, and how the first drug felt. A prescribing clinician should advise on any treatment change.

2primary sources, each with the day we read it — open the documents used on this page