Retatrutide Dosage Chart (2026): Weekly Schedule, Titration and Syringe Units

Retatrutide is newer than semaglutide and tirzepatide and the human data is still emerging. What follows is what the phase 2 trial established, what protocols are in use off-label, and where the two diverge, which on an investigational compound is a wider gap than usual.

What Is Retatrutide and How It Works

Retatrutide is a triple GLP-1, GIP, and glucagon receptor agonist. Translation: it activates three different metabolic pathways related to weight loss and blood sugar control. This triple mechanism is why early data suggests it might be more effective than semaglutide or tirzepatide.

The clinical trials were originally run for diabetes, but the weight loss results were so pronounced that interest exploded for weight loss applications.

Clinical Trial Dosing Protocols

The Phase 2 obesity trial (Jastreboff et al., NEJM 2023) used weekly subcutaneous injections with dose escalation over 48 weeks. The trial tested four target maintenance doses: 1 mg, 4 mg, 8 mg, and 12 mg weekly. The 8 mg and 12 mg arms used a stepwise escalation. The 12 mg titration arm went 2 mg → 4 mg → 8 mg → 12 mg, with each step held for several weeks.

• 1 mg weekly (low-dose arm, no escalation)
• 4 mg weekly (titrated from 2 mg starting dose)
• 8 mg weekly (titrated 2 → 4 → 8 mg)
• 12 mg weekly (titrated 2 → 4 → 8 → 12 mg)

These doses are for weekly subcutaneous injection. Retatrutide has a long half-life that supports once-weekly dosing.

Weight Loss Results by Dose

At 48 weeks in the Phase 2 obesity trial, mean weight loss was approximately 17% on the 4 mg arm, 23% on the 8 mg arm, and 24% on the 12 mg arm. The 1 mg arm produced approximately 8% loss. These are mean changes from baseline (placebo lost 2.1%) over the full 48-week trial, not 12 to 16 weeks (Jastreboff et al., NEJM 2023). Earlier reports from the press cycle that conflated short-window loss with the 48-week endpoint should be treated skeptically; the high-percentage figures took the better part of a year of weekly dosing to reach.

For context, semaglutide (Wegovy) at 2.4 mg weekly produced approximately 15% mean loss in STEP 1 over 68 weeks, and tirzepatide (Zepbound) at 15 mg produced approximately 21% mean loss in SURMOUNT-1 over 72 weeks. Retatrutide at the high-dose arm appears modestly more effective than tirzepatide, but the trials use different timeframes and populations, so direct comparison is approximate.

Phase 3 (the TRIUMPH program) is ongoing. FDA approval is most likely 2027 or 2028 based on typical timelines from Phase 3 readout to approval.

Current Off-Label Dosing Approaches

Retatrutide is not FDA approved as of April 2026. Off-label dosing is emerging through telehealth-affiliated compounding pharmacies and from research peptide sources. Community protocols vary, and they do not necessarily mirror the published trial titration. Some users start at 1-2 mg weekly and escalate; others follow the trial's stepwise approach. There is no validated short-cycle protocol, the published efficacy figures come from the 48-week trial window, and shorter cycles will produce proportionally smaller results.

If you are following the Phase 2 trial as a reference, the conservative path is to start at 2 mg weekly, hold each step for at least four weeks, and escalate only if tolerated. Pushing past 12 mg has no published trial support.

Side Effects at Different Doses

The most common side effects in the trial were gastrointestinal, nausea, diarrhea, and vomiting, and they were dose-dependent. The 12 mg arm had higher GI adverse-event rates than the 1 mg arm, which is consistent with the broader GLP-1 literature. Nausea typically peaks shortly after a dose escalation step and improves over the following one to two weeks as tolerance develops.

At 1-2 mg weekly: GI side effects are usually mild. Many participants report little or nothing.

At 4-8 mg weekly: Nausea is common, especially in the days following a step up. Most people adapt within a week.

At 12 mg weekly: Nausea, diarrhea, and reduced appetite are more pronounced. A subset of trial participants discontinued at this dose for tolerability.

As with semaglutide and tirzepatide, the boxed warning on the GLP-1 class flags personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) as contraindications. Pancreatitis and gallbladder events are also class-level concerns.

Appetite Suppression

The central mechanism of weight loss is reduced caloric intake driven by appetite suppression and slower gastric emptying. Hunger and food cravings drop; meals feel satisfying at smaller volumes.

At trial doses above 4 mg, appetite suppression can be substantial enough that protein intake becomes a deliberate decision rather than a hunger-driven one. The standard recommendation in obesity-medicine practice is 1.6 grams of protein per kilogram of body weight per day during a GLP-1 cycle, both to preserve lean mass and to maintain a sense of meal satisfaction.

Comparing to Semaglutide and Tirzepatide

Semaglutide is a GLP-1 receptor agonist. Effective weight-loss dose is 2.4 mg weekly (Wegovy), reached by titrating through 0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg over roughly 16 weeks.

Tirzepatide is a dual GLP-1 / GIP receptor agonist. Effective weight-loss doses are 5, 10, or 15 mg weekly (Zepbound), reached by titrating in 2.5 mg steps every four weeks.

Retatrutide adds glucagon receptor activation as a third pathway. Phase 2 data shows it produces somewhat greater mean weight loss than tirzepatide at the upper-dose arm, but it is not yet approved and the long-term safety profile beyond 48 weeks is still being characterized in Phase 3.

Pricing and Availability

Retatrutide isn't available through mainstream pharmacies yet. Telehealth clinics are starting to offer it, often through compounding arrangements. Pricing varies wildly.

Reported clinic pricing runs roughly $300 to $800 a month depending on dose and provider, which is higher than semaglutide or tirzepatide through the same channels, reflecting that retatrutide is investigational rather than approved.

From Limitless Life Peptides' resources, the consensus is that as retatrutide becomes more available, pricing should normalize lower.

Important Considerations Before Using

You need to be realistic about side effects. Retatrutide will likely suppress your appetite significantly. If you don't like that feeling or if you struggle to eat enough with suppressed appetite, this might not be right for you.

You need adequate protein intake. The appetite suppression can lead to muscle loss if you're not intentional about protein. Some people do high-protein drinks even when not hungry to protect muscle.

You need to be consistent. Weekly injections need to happen on schedule. Missing doses reduces effectiveness.

Realistic Expectations

The Phase 2 trial averaged its weight-loss endpoints at 24 weeks and 48 weeks. Translating to a personal trajectory: visible appetite suppression starts within the first one to two weeks, but the bulk of weight loss accumulates over months, not weeks. In the trial, mean weight loss at 24 weeks was already about 17% on the 8 mg and 12 mg arms (17.3% and 17.5%, against 1.6% on placebo) and reached about 23% and 24% by 48 weeks (22.8% and 24.2%, against 2.1% on placebo), per the phase 2 trial in the New England Journal of Medicine.

Plateau is real. After the appetite-suppression window stabilizes, further loss generally requires deliberate caloric awareness rather than relying on hunger reduction alone.

The Future of Retatrutide

Phase 3 trials (the TRIUMPH program) are ongoing. Based on standard Phase 3 timelines, FDA approval is most plausible in 2027 or 2028 rather than 2026. Once approved, retatrutide will move to mainstream pharmaceutical channels, which historically increases supply and pulls cash prices down over the first year.

Key Takeaways

• Phase 2 obesity-trial doses were 1, 4, 8, and 12 mg weekly, titrated stepwise, not 0.25 → 2.5 mg
• Mean weight loss at 48 weeks was approximately 8% (1 mg), 17% (4 mg), 23% (8 mg), and 24% (12 mg)
• Side effects (nausea, diarrhea, vomiting) are dose-dependent and broadly similar to other GLP-1 class drugs
• Retatrutide is not FDA approved as of April 2026; FDA approval is most likely 2027-2028
• Boxed-warning contraindications (personal or family history of MTC or MEN 2) apply across the GLP-1 class
• Adequate protein intake (≈1.6 g/kg/day) is the standard recommendation to preserve lean mass during a GLP-1 cycle
• The dramatic weight-loss figures in headlines come from 48-week trial endpoints, not short-window outcomes

Frequently Asked Questions

How many units is 4 mg of retatrutide on an insulin syringe?

It depends on the concentration. A 10 mg vial mixed with 2 mL of bacteriostatic water is 5 mg/mL, so 4 mg is 0.8 mL, which reads as 80 units on a U-100 syringe. The same vial in 1 mL is 10 mg/mL and 4 mg reads as 40 units. The chart at the top of this page lists every step of the trial ladder at both concentrations.

What is the typical retatrutide dosage per week?

Retatrutide is a once weekly subcutaneous injection. The Phase 2 obesity trial tested four weekly maintenance doses: 1 mg, 4 mg, 8 mg and 12 mg. Nobody starts at a maintenance dose. The higher arms were reached by stepwise escalation, and the 12 mg arm climbed 2 mg, then 4 mg, then 8 mg, then 12 mg, holding each step for several weeks. There is no approved dose because retatrutide is not an approved drug.

What is the standard retatrutide dosage schedule?

The trial schedule started at 2 mg weekly and doubled at fixed intervals, holding each step long enough for gastrointestinal side effects to settle before the next increase. That stepwise shape, rather than any single number, is the part worth copying. Escalating faster than the trial did is the most common way people generate nausea severe enough to make them stop.

How do I convert a retatrutide dose into syringe units?

Work out the concentration first, then read the barrel. Concentration equals vial strength divided by the bacteriostatic water you added. On a U-100 insulin syringe, 100 units is 1 mL, so units equals your dose in mg divided by the concentration in mg per mL, multiplied by 100. A 10 mg vial in 2 mL gives 5 mg/mL, at which a 4 mg dose reads as 80 units.

Is there a retatrutide dosage calculator?

Yes. The Bureau runs a free retatrutide calculator that takes vial strength, water volume and target dose and returns the exact mark on the syringe, which removes the arithmetic step where most dosing errors happen. It is linked from this page.

Can women use the same retatrutide dosage as men?

The published trial protocols did not set separate dose schedules by sex, and the escalation steps were the same for all participants. Body weight and tolerance drive far more of the practical difference than sex does. Retatrutide is an unapproved compound sold for research use only, so any use sits outside a supervised clinical setting and carries that risk.