Weight Loss  /  Retatrutide
For Adults · Compounded · Investigational

Retatrutide

An investigational triple-agonist peptide.

An investigational medicine that acts on three hormone receptors — GIP, GLP-1 and glucagon — and is still in Phase 3 clinical trials. Not FDA-approved for any use. Prescribed online only at a licensed provider's discretion and dispensed with vitamin B12 (cyanocobalamin), at the strength your provider prescribes.

1 mg2 mg4 mg6 mg8 mg12 mg15 mg

$499/mo

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ForbiddenRx Retatrutide
At a glance
Cadence
Set by your prescriber
Status
Investigational · Phase 3
Form
Subcutaneous injection
Class
GIP + GLP-1 + glucagon
Prescription
Provider discretion
For
Adults
The basics

What is retatrutide?

What it is
A compounded prescription injection
FDA status
Investigational · not FDA-approved for any use
Drug class
GIP + GLP-1 + glucagon receptor agonist
Made by
U.S. 503A compounding pharmacy
Branded product
None exists
Dosing
Set by your prescriber
Prescription
Provider discretion · no insurance required
Shipping
Discreet, unmarked · most U.S. states
Start your online visit →

Retatrutide is an investigational peptide that acts on three hormone receptors at once — GIP, GLP-1 and glucagon — which is why it is often called a triple agonist. It is being developed for weight management and related metabolic conditions and is currently in Phase 3 clinical trials.

Retatrutide is not FDA-approved for any use, and no branded retatrutide product exists. What is dispensed here is a compounded preparation made by a U.S. 503A pharmacy for an individual patient, and compounded drugs are not reviewed by the FDA for safety or effectiveness. Because it is still being studied, far less is known about it than about approved medicines such as tirzepatide or semaglutide.

It is prescribed only where a licensed provider determines it is appropriate after reviewing your health history. The strength and schedule are set by your prescriber. Individual results are not guaranteed.

Understanding the interest

Why does retatrutide come up so often?

Appetite, fullness and energy use are governed by gut and pancreatic hormones, and the medicines that mimic them have changed weight care. Retatrutide adds a third pathway — glucagon — to the GIP and GLP-1 signals that tirzepatide targets, which is why it draws attention. The research is still under way, and it remains an investigational medicine.

✔Weight is biology, not a lack of discipline

Appetite hormones, metabolism, and set-point all work against sustained weight loss — which is why so many people plateau despite real effort.

✔Newer means less is known

Retatrutide has not completed the trials that approved medicines have. A provider weighs that against your history before deciding whether it is appropriate.

Know the difference

Prescribed retatrutide vs. "research" peptides vs. diet alone — what's the difference?

The short answer: diet and exercise address behavior, "research use only" peptides sold online carry no prescription, no pharmacy and no accountability, and prescribed retatrutide is compounded by a licensed 503A pharmacy against a provider's order written for you.

 Diet & exercise alone"Research" peptides onlinePrescribed retatrutide (Rx)
SourceNot applicableUnlicensed sellersU.S. 503A compounding pharmacy
PrescriptionNoNo — "not for human use"Yes — written for you
Provider involvedNoNoYes — reviews your health history first
Your name on the labelNot applicableNoYes, with Rx number and pharmacy
FDA-approvedNot applicableNoNo — investigational, compounded

Retatrutide is not FDA-approved in any form. If you are going to take it, take one a licensed provider prescribed and a 503A pharmacy compounded with your name on it.

How it works

How does retatrutide work?

It is designed to act on three hormone receptors — GIP, GLP-1 and glucagon — that together influence appetite, digestion, blood sugar and energy use. How that translates into effects in people is what the ongoing trials are studying.

I

GLP-1 receptor

The same pathway semaglutide targets, involved in fullness and appetite signaling.

II

GIP receptor

The second pathway tirzepatide adds, involved in how the body handles nutrients after a meal.

III

Glucagon receptor

The third pathway, studied for its role in energy expenditure and liver fat. This is what makes retatrutide a triple agonist.

Who it's for

Who is retatrutide for?

It's for adults working on their weight under the guidance of a licensed provider who has reviewed their history and decided an investigational option is appropriate.

✔Adults ready to work on their weight

Those pairing medication with real nutrition and lifestyle change, under a provider who reviews their history first.

✔You understand it is investigational

You know retatrutide is still in clinical trials and not FDA-approved, and want it prescribed properly rather than bought from a grey market.

✔You want the dosing decided for you

Strength and schedule are set by your prescriber, not selected here.

✔Already familiar with GLP-1 medicines

On a GLP-1 elsewhere? A provider can review your history and decide what fits.

✕When it's not the right fit

Retatrutide is not for those with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN2), a history of pancreatitis, or who are pregnant or planning pregnancy. If you would rather use an FDA-approved active ingredient, Tirzepatide or Semaglutide may fit better — mention your goals and full history in your visit.

How to get it

How do I get retatrutide online?

You complete a private online visit, a licensed provider reviews it, and — if they determine it is appropriate — your prescription ships to your door. No insurance required, no in-person appointment, no waiting room.

Complete your online visit

Answer a short set of health questions and share your height and weight — on your own time, no appointment.

Provider review

A provider licensed in your state reviews your information and decides whether retatrutide is appropriate. Approval is never guaranteed.

Shipped to your door

If prescribed, your medication ships discreetly from a U.S. 503A pharmacy, with ongoing provider support.

Pricing is shown at checkout — no insurance needed, no hidden fees.

Using it & safety

How do I take it, and is it safe?

You take it exactly as your label directs. The strength and schedule are set by your prescriber — we deliberately do not publish a dosing regimen here, because that is a clinical decision about you.

How to take retatrutide

Form
A subcutaneous injection from a compounded vial.
Schedule
Set by your prescriber and printed on your label.
Strength
Chosen by your provider and adjusted based on how you respond.
Support
Questions? Email or call our support team; anti-nausea support is available if needed.
Missed dose
Ask your provider about timing before your next injection.
InjectionInvestigationalProvider-set

Safety & side effects

⚠ Investigational — not FDA-approved

Retatrutide is still in clinical trials and its long-term safety profile is not yet established. It is a compounded preparation, not an FDA-approved medication, and is not for those with a personal or family history of MTC or MEN2, a history of pancreatitis, or who are pregnant. Tell your provider about your full medical history and every medication you take.

In clinical trials the most commonly reported effects were gastrointestinal, similar to other medicines in this family. Possible side effects include:

  • Nausea
  • Diarrhea
  • Vomiting
  • Constipation
  • Reduced appetite
  • Increased heart rate
  • Injection-site reactions

Contact our support team if side effects persist or worsen. Seek immediate care for severe or persistent abdominal pain (possible pancreatitis), a racing or irregular heartbeat, or signs of an allergic reaction.

Compare your options

Which treatment fits you?

A side-by-side look at the weight-loss options available through ForbiddenRx. Your provider helps you choose what's right.

TreatmentWhat it isReceptorsRouteStatusRx required
Retatrutide
This page		Triple agonistGIP + GLP-1 + glucagonInjectionInvestigationalYes
TirzepatideDual agonistGIP + GLP-1InjectionApproved ingredient, compoundedYes
SemaglutideGLP-1 receptor agonistGLP-1InjectionApproved ingredient, compoundedYes
Oral SemaglutideGLP-1 in daily tablet formGLP-1TabletApproved ingredient, compoundedYes
Questions, answered

Retatrutide FAQ

Is retatrutide FDA-approved?

No. Retatrutide is an investigational medicine still in Phase 3 clinical trials. It is not FDA-approved for any use and no branded retatrutide product exists. What is dispensed here is a compounded preparation, prescribed only at a licensed provider's discretion.

How is retatrutide different from tirzepatide or semaglutide?

Semaglutide acts on the GLP-1 receptor, tirzepatide on GIP and GLP-1, and retatrutide on three receptors — GIP, GLP-1 and glucagon. It is often called a triple agonist. Much less is known about it than about the approved medicines, which is why your provider decides whether it is appropriate for you.

What does the research show?

Retatrutide has been studied in clinical trials, including a Phase 2 obesity trial published in the New England Journal of Medicine in 2023 (Jastreboff et al.), and larger Phase 3 trials are under way. Trial results are not a promise of what any individual will experience, and the long-term safety profile is still being established.

How is it taken?

In clinical trials retatrutide has been given as a once-weekly subcutaneous injection. Your provider sets the strength and schedule; we do not publish a dosing regimen here.

Who should not take it?

It is not appropriate for people with a personal or family history of medullary thyroid cancer (MTC) or MEN2, a history of pancreatitis, or who are pregnant or planning pregnancy, among other conditions. Share your full medical history so your provider can decide whether it is safe for you.

Do I need insurance?

No. ForbiddenRx works without insurance — you complete an online visit and, if a provider prescribes it, your medication ships directly to you. A prescription is not guaranteed and is subject to provider review of your health history.

Credibility you can verify

Care held to a higher standard

Licensed Providers

U.S. board-certified clinicians

503A Pharmacies

U.S.-based compounding partners

Most U.S. States

We confirm your state during intake

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Injection · GLP-1

Semaglutide

A single-receptor GLP-1 — a weekly injection.

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Category

Weight Loss

Compare every medically-supervised weight-loss option available through ForbiddenRx.

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Ask about retatrutide

Complete a private online visit and a licensed provider reviews your history and decides whether retatrutide, or another option, is appropriate for you.

Start your online visit →

  • Discreet, unmarked packaging
  • 503A-compounded, your name on the label
  • Questions? Email or call our support team
  • Licensed providers in most U.S. states
Medically reviewed

Sources & references

Medically reviewed by ForbiddenRx Medical Affairs — Independent, licensed medical providers · Last reviewed October 2026. This page was written and is periodically reviewed for medical accuracy in line with clinical guidance followed by the independent, licensed medical providers in the ForbiddenRx network. It is provided for general educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Always talk with a licensed provider about your individual health.

  1. Jastreboff AM et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. New England Journal of Medicine, 2023.
  2. ClinicalTrials.gov (U.S. National Library of Medicine). Studies of retatrutide.
  3. U.S. Food & Drug Administration. Compounding and the FDA: Questions and Answers.
For further reading

Clinical references

This page is educational and is not medical advice.