Retatrutide Dosing Schedule: Complete Guide to Weekly Doses and Titration

The retatrutide dosing schedule starts at 1 mg weekly and increases every 4 weeks until reaching 8 to 12 mg. Most people begin with 1 mg for the first month, then move to 2 mg, 4 mg, 8 mg, and finally 12 mg as their maintenance dose. This gradual increase helps your body adjust and reduces side effects like nausea.

Below you'll find the full breakdown: weekly dose amounts, how long each phase lasts, what results to expect at different doses, and practical tips for managing side effects.

Quick Reference: Retatrutide Titration Chart

Weeks	Weekly Dose	Notes
1-4	1 mg	Starting dose; body adjusts to medication
5-8	2 mg	First increase; watch for GI symptoms
9-12	4 mg	Noticeable appetite suppression begins
13-16	8 mg	Significant weight loss typically observed
17+	12 mg	Maximum dose; maintenance phase

Some protocols use slightly different schedules. Clinical trials tested various escalation patterns, including jumping from 4 mg directly to 8 mg. The table above reflects the most gradual approach, which tends to produce fewer side effects.

Why Gradual Dose Increases Matter

Jumping straight to higher doses causes problems. In Phase 2 trials, participants who started at 4 mg instead of 2 mg experienced nearly double the rate of GI symptoms. Nausea, vomiting, diarrhea, and stomach pain all increased.

The gradual approach works because your gut needs time to adapt. Retatrutide activates three different hormone receptors: GLP-1, GIP, and glucagon. Each one affects digestion. Flooding your system with high doses before it adjusts leads to miserable side effects and higher dropout rates.

Four weeks per dose level is the standard pace. If side effects hit hard, your provider might keep you at the same dose for an extra two to four weeks before moving up.

Weight Loss Results by Dose Level

Not all doses produce equal results. The Phase 2 trial data showed a clear pattern: higher doses meant more weight loss.

At 24 weeks:

• 1 mg group: 7.2% body weight reduction
• 4 mg group: 12.9% reduction
• 8 mg group: 15.7% reduction
• 12 mg group: 17.5% reduction
• Placebo: 1.6% reduction

At 48 weeks:

• 1 mg group: 8.7% reduction
• 12 mg group: 24.2% reduction
• Placebo: 2.1% reduction

The 12 mg group stood out. Every single participant in that group lost at least 5% of their body weight. 93% lost 10% or more. 83% hit the 15% threshold.

For context, losing 24% of your body weight in under a year represents dramatic results. Someone weighing 250 pounds at baseline would drop roughly 60 pounds on average.

Starting Your First Dose

Week one feels different for everyone. Some people notice appetite changes immediately. Others feel nothing for the first few weeks.

The 1 mg starting dose isn't designed to produce major weight loss. It primes your body for what's coming. Think of it as letting your digestive system get familiar with the medication before ramping up.

Common experiences during the first month include mild nausea (usually passes within days), slight reduction in appetite, occasional fatigue, and some people report nothing at all. All of these are normal.

The Middle Doses: 2 mg Through 8 mg

This is where most of the adjustment happens. Between weeks 5 and 16, your body goes through the biggest changes.

The 2 mg to 4 mg transition often brings the first real appetite suppression. Meals feel more satisfying. Cravings drop. Many people find they simply forget to eat.

Moving to 8 mg typically marks a turning point. Trial data showed this dose produced significant reductions in body weight while remaining tolerable for most participants. Some providers consider 8 mg the "sweet spot" for balancing results against side effects.

If you're doing well at 8 mg without major side effects, pushing to 12 mg may or may not be worth it. That's a conversation to have with your healthcare provider.

Reaching and Maintaining 12 mg

The maximum studied dose delivers the strongest results. But it also carries the highest rate of side effects.

Once you reach 12 mg, the titration phase ends. This becomes your maintenance dose for as long as you continue treatment. Phase 2 trials lasted 48 weeks, so we have solid data on that timeframe.

Questions remain about longer-term use. Phase 3 trials running now will provide more answers. Some participants have now been on the medication for well over a year.

Managing Side Effects During Dose Increases

GI symptoms hit hardest during the first few weeks after each dose bump. Here's what helps.

Timing your injection: Try injecting at night before bed. You sleep through the worst of any initial nausea. Some people find this makes a significant difference.

Eating around the medication: Don't inject on a completely empty stomach. A small meal beforehand seems to help. After the injection, stick to bland foods for a day or two.

Smaller, frequent meals: Big portions trigger more nausea when retatrutide is active. Eating smaller amounts more often puts less strain on your digestive system.

What to avoid: Greasy food, heavily spiced dishes, and large meals all tend to worsen symptoms. Alcohol can make nausea worse too.

When symptoms persist: If nausea or vomiting doesn't improve after two weeks at a new dose, talk to your provider. Anti-nausea medication like ondansetron can help bridge the adjustment period. Your doctor might also extend your current dose phase before moving up.

Most GI symptoms fade substantially after 8 to 12 weeks, especially with gradual dose increases.

How to Administer the Injection

Retatrutide goes under the skin, not into muscle. This is called subcutaneous injection. You do it once weekly on the same day each week.

Where to inject: The abdomen works best for most people because of the fat layer there. The thigh and upper arm are alternatives. Pick a spot with some padding.

Rotating sites: Don't use the same exact spot every week. Move at least an inch away from your last injection. Staying in one area causes lumps under the skin over time, which can affect absorption and become uncomfortable.

The process: Clean the area with an alcohol swab first. Let it dry completely. Pinch the skin, insert the needle at a 45 to 90 degree angle, push the plunger slowly, then remove straight out. Apply light pressure with gauze if needed.

Temperature matters: Take the medication out of the fridge 30 minutes before injecting. Room temperature feels more comfortable going in.

Comparing Retatrutide Doses to Other Medications

Retatrutide uses much higher milligram doses than semaglutide. This doesn't mean it's "stronger" milligram for milligram. The compounds are simply different.

Semaglutide (Wegovy, Ozempic) starts at 0.25 mg and maxes out at 2.4 mg. Tirzepatide (Mounjaro, Zepbound) starts at 2.5 mg and goes up to 15 mg. Retatrutide's range of 1 mg to 12 mg falls between these.

The key difference is mechanism. Semaglutide hits one receptor. Tirzepatide hits two. Retatrutide hits three. That triple action on GLP-1, GIP, and glucagon receptors appears to explain why it produces the highest weight loss percentages seen in trials so far.

What If You Miss a Dose?

Clinical trial protocols provide some guidance here. If you miss your scheduled injection day, take it as soon as you remember, as long as at least 3 days remain before your next scheduled dose. If less than 3 days remain, skip the missed dose and resume your normal schedule.

Don't double up. Taking two doses close together won't improve results and will likely make side effects worse.

Adjusting the Schedule If Needed

Not everyone follows the standard 4-week escalation. Reasons to slow down include severe nausea or vomiting that doesn't improve, significant diarrhea or constipation, weight loss happening faster than desired, or doctor recommendation based on your response.

Stretching each dose phase to 6 or 8 weeks is completely reasonable. The goal is reaching an effective maintenance dose while staying comfortable enough to continue treatment.

Going faster than 4 weeks per phase isn't typically recommended. Faster titration correlates with worse side effects and higher dropout rates in trial data.

Current Availability and Important Warnings

Retatrutide has not received FDA approval. It remains in Phase 3 clinical trials through Eli Lilly's TRIUMPH program. The only legitimate way to access it currently is through enrollment in an active clinical trial.

Analysts project FDA approval could happen in 2026 or 2027 if trials succeed.

The FDA has issued explicit warnings about compounded or "research" versions of retatrutide sold online. These products are not legal for human use and carry unknown safety risks. Multiple companies have received warning letters for selling such products.

Any website claiming to sell prescription retatrutide in 2025 is not operating within FDA guidelines.

Disclaimer

This article is for informational purposes only and does not constitute medical advice. Retatrutide is not FDA-approved and is currently available only through clinical trials. Dosing information comes from published Phase 2 trial data and may change based on Phase 3 results and eventual prescribing guidelines. Consult a qualified healthcare provider before starting any weight loss medication.

Sources

• Triple-Hormone-Receptor Agonist Retatrutide for Obesity - New England Journal of Medicine
• Retatrutide Dosage Guide & Titration Schedule 2025 - BodySpec
• Retatrutide Dosing: Weekly Injections, Clinical Trials & Weight Loss Results - Swolverine
• Retatrutide Dosage: a Guide - IAPAM
• How to Inject Retatrutide - NowPatient
• Retatrutide Side Effects: Safety and Management Guide - BodySpec
• FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss - FDA