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The Dual Agonist

Tirzepatide

Also known as Zepbound · Mounjaro

Prescription · work with your prescriberSummary coverage

At a glance

What it is
Dual GLP-1 and GIP agonist: approximately 22.5% loss, FDA-approved.
Evidence
Clinical trialsHow the tiers workSURMOUNT-1 enrolled 2,539 participants and the compound has been FDA-approved since 2023, though post-market data is still accumulating relative to semaglutide. Why this tier
Half-life
About 5 to 6 days
From Zepbound prescribing information, section 12.3, April 2026
Routes
Subcutaneous
Category
Metabolic
FDA
FDA-approved
As of 3 August 2026. What that means
WADA
Monitoring Program

Putting Tirzepatide on a schedule, with the vial it comes from and a log of each dose, happens in the app: Claritide for iPhone.

Evidence

Why this tier

SURMOUNT-1 enrolled 2,539 participants and the compound has been FDA-approved since 2023, though post-market data is still accumulating relative to semaglutide.

Overview

What it is

Tirzepatide is a dual GLP-1 and GIP receptor agonist, FDA-approved in 2023 as Zepbound for weight loss and as Mounjaro for type 2 diabetes. The SURMOUNT-1 trial showed approximately 22.5% mean body weight loss at 72 weeks on 15 mg weekly. It sits between semaglutide and retatrutide on both efficacy and evidence maturity.

Mechanism

How it works

Tirzepatide activates two incretin receptors instead of one. The GLP-1 half does what semaglutide does: reduces appetite, slows gastric emptying, improves insulin secretion. The GIP half adds a second appetite-regulating route through brain receptors distinct from GLP-1, enhances insulin sensitivity, and modulates fat metabolism, possibly reducing lipid storage. GIP and GLP-1 together account for roughly 50–70% of the insulin secreted after a meal, so hitting both produces a more complete incretin response than either alone. Our sources also note it may improve the ratio of fat loss to lean mass loss compared with GLP-1 alone.

Dosing

Commonly researched ranges

These are figures reported in published literature and practitioner protocols: a commonly researched range, not a recommendation. Claritide does not tell you what to take.
  • Trial maximum15 mg

    Once weekly · Same day each week

    SURMOUNT-1 studied doses up to 15 mg weekly. Our sources do not publish the full titration schedule. This is prescription-directed dosing.

Cycle guidance
Not cycled. Prescribed as ongoing therapy; weight regain is expected on discontinuation.
Goals
Fat loss
Legal standing

Where this sits with the FDA

Dated, sourced, and separate from whether it works. Removal from a warning list is not permission to compound.
FDA-approvedas of 3 August 2026 · US

FDA-approved drug product; compounded tirzepatide is not permitted

The approved products are legitimate; the compounded route is closed. 503A enforcement discretion ended 5 March 2025 and 503B ended 19 March 2025, and tirzepatide is on neither the 503B bulks list nor the shortage list.

Last change · 30 April 2026 · FDA proposed permanently excluding tirzepatide from the 503B bulks list. The comment period closed 29 June 2026 and a final determination is pending.

Primary source

How it got here

  1. 5 March 2025

    FDA enforcement discretion for 503A compounded tirzepatide ended.

  2. 19 March 2025

    FDA enforcement discretion for 503B compounded tirzepatide ended.

  3. 1 January 2026

    January 2026 label revisions to the Mounjaro Important Administration Instructions and a new “Never Share a MOUNJARO KwikPen” warning (5.10); Severe Gastrointestinal Adverse Reactions (5.6) was added in December 2025.

  4. 30 April 2026

    FDA proposed excluding semaglutide, tirzepatide and liraglutide from the 503B bulks list permanently; comments closed 29 June 2026.

Sport

WADA status

The 2026 Prohibited List entered force on 1 January 2026.
Monitoring Program

Not prohibited. Tirzepatide sits on WADA’s 2026 Monitoring Program, item 6, in and out of competition. Monitoring Program data is collected to detect patterns of misuse; it does not itself trigger a sanction.

Reconstitution

There is nothing to mix

Not applicable. None of the published routes for this compound take a diluent, so there is no concentration to calculate and no beyond-use window to track.

Expectations

Week by week

What our material describes people reporting. Individual responses vary widely.
  1. 1
    Week 72

    SURMOUNT-1 showed 22.5% mean body weight loss at 72 weeks on 15 mg, with the curve still declining. Our sources note the maximum effect may not have been reached.

Tolerability

Side effects

Grouped by how often our sources report them. Percentages appear only where a published trial figure exists.

Common

  • NauseaGI effects may be slightly more intense during escalation than with semaglutide.
  • Vomiting
  • Diarrhea
  • Constipation
  • Lean mass lossResistance training and adequate protein are the standard countermeasures. In the BMJ network meta-analysis tirzepatide reduced fat mass most (−25.7%) and also lean mass most (−8.3%).

Uncommon

  • Gallbladder eventsAssociated with rapid weight loss from any cause.
  • Alopecia (hair loss)Listed under postmarketing experience on the Mounjaro label. Postmarketing reports come from a population of uncertain size, so no rate can be calculated from them.
Safety

Contraindications and interactions

Do not use if

  • Personal or family history of medullary thyroid carcinoma (MTC) or MEN2: boxed warning across the GLP-1 class
  • Pregnancy: discontinue well before a planned pregnancy
  • History of pancreatitis (class-wide monitoring concern)
  • Severe gastroparesis: Severe Gastrointestinal Adverse Reactions was added to the label as Warnings 5.6 in December 2025
  • Planned general anaesthesia or deep sedation: retained gastric contents raise the risk of pulmonary aspiration. Tell the anaesthetist you are on a GLP-1

Interactions

  • Oral hormonal contraceptivescaution

    This instruction is tirzepatide-specific and does not transfer to semaglutide. The Mounjaro label directs switching to a non-oral contraceptive method, or adding a barrier method, for 4 weeks after starting and for 4 weeks after each dose escalation.

  • Warfarin and other narrow-therapeutic-index oral drugsmonitor

    Delayed gastric emptying lowers peak concentration and delays time to peak. The label names warfarin and directs increased clinical or laboratory monitoring for drugs with a narrow therapeutic index; it does not direct a dose change.

  • Insulin and sulfonylureascaution

    Hypoglycemia risk.

Absence from this list does NOT mean safety. It means lack of research.

Handling

Storage and cost

Storage
Prescription pens follow the manufacturer storage instructions. The pen arrives as a solution, so there is nothing to reconstitute, no concentration to calculate and no beyond-use window to track.
Cost
$1060 per month (list price, coverage expanding)
Deep dive

Tirzepatide in full

Limited coverage

Tirzepatide appears in our comparison and guide content rather than as a dedicated guide. This record covers what our sources state.

What it is

A dual GLP-1 and GIP receptor agonist. FDA-approved in 2023 as Zepbound for weight loss, and as Mounjaro for type 2 diabetes. It sits between semaglutide and retatrutide on both potency and evidence maturity.

The second receptor

GLP-1 activation does the familiar work: appetite reduction, slowed gastric emptying, improved insulin secretion. GIP activation adds enhanced insulin sensitivity, modulated fat metabolism, and a second appetite-regulating route through brain receptors distinct from the GLP-1 ones.

Together, GIP and GLP-1 account for roughly 50–70% of the insulin secreted after a meal, so engaging both produces a more complete incretin response than either alone. Our sources also note tirzepatide may improve the ratio of fat loss to lean mass loss compared with GLP-1 monotherapy, relevant if body composition rather than scale weight is the goal.

What the trial showed

SURMOUNT-1, 2,539 participants: approximately 22.5% mean body weight loss at 72 weeks on 15 mg weekly. Notably, the curve was still declining at 72 weeks, suggesting the maximum effect had not been reached.

For comparison, semaglutide's STEP 1 produced 14.9% at 68 weeks, and retatrutide's TRIUMPH-1 Phase 3 reported 28.3% at 80 weeks on 12 mg, a conference presentation with no registry results posted, against a published trial.

Discontinuation rates were around 6–14%.

Dosing

Our sources state a maximum studied dose of 15 mg once weekly by subcutaneous injection. They do not publish the full titration schedule, so we do not either. This is a prescription medication with prescriber-directed titration.

The cautions our sources raise

Same class warnings as semaglutide: the MTC and MEN2 boxed warning, gallbladder events with rapid weight loss, pancreatitis as a monitored class concern, lean mass loss alongside fat, and altered absorption of oral medications. GI side effects may be slightly more intense during escalation than with semaglutide. Post-market safety data is still accumulating given the 2023 approval.

References

Sources

  1. 1
    Jastreboff et al., 2022 · Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1), NEJM 387

Every record in this library is free to read, and it stays free. Your own schedule, vials and log live in the app: Claritide for iPhone.