Retatrutide Dosage Chart: Week-by-Week Guide

Direct answer: The standard retatrutide dosage chart runs 2 mg → 4 mg → 8 mg → 12 mg, holding four weeks at each tier. The slower Phase 3 TRIUMPH protocol starts at 0.5 mg and reaches up to 15 mg over 36–40 weeks. Both schedules, all draw volumes, and a comparison against tirzepatide are in the tables below.

28.7% Mean body weight loss at 12mg/week over 68 weeks (TRIUMPH-4 Phase 3)

~6 days Half-life — supports once-weekly dosing, steady state in 4–5 weeks per tier

4 weeks Minimum time at each dose before escalating — skipping this causes most GI side effects

Starting dose is 2mg/week (Phase 2 protocol) or 0.5mg/week (Phase 3 TRIUMPH protocol) — both are legitimate depending on your starting point and GI sensitivity
Maximum studied dose is 12mg/week (Phase 2) and 15mg/week (Phase 3 TRIUMPH high arm)
Every dose increase requires a full 4-week hold — rushing is the #1 cause of early dropouts
Your syringe draw volume changes at every dose tier depending on how you reconstituted — the tables below remove all guesswork
Retatrutide outperforms semaglutide and tirzepatide on weight loss endpoints in every head-to-head metric so far
Missed doses have a specific recovery protocol — it's not just "inject when you remember"

The dose range for retatrutide spans 0.5 mg to 15 mg per week depending on the protocol, but the math gets messier once you factor in vial concentrations, syringe units, reconstitution volumes, and what happens when you stall at 8 mg or have a rough week at 4 mg. This page gives you every table you need: week-by-week titration, dose-by-concentration draw volumes, unit conversions, and a head-to-head comparison against semaglutide and tirzepatide. Print it. Bookmark it. Tape it inside your cabinet door.

What Is the Retatrutide Dosage Range?

Retatrutide (LY3437943) is a triple-agonist peptide developed by Eli Lilly. It targets GLP-1, GIP, and glucagon receptors simultaneously — that third receptor (glucagon) is what separates it from tirzepatide and likely explains the additional 4–6% weight loss edge in clinical comparisons.

The dose range for retatrutide studied in humans:

Minimum therapeutic dose: 2mg/week (Phase 2) / 0.5mg/week (Phase 3 initiation)
Common maintenance dose: 8–12mg/week
Maximum studied dose: 12mg/week (Phase 2) / 15mg/week (Phase 3 TRIUMPH)
Initiation dose (never skip this): 2mg/week or lower

There is no approved FDA dose yet. Approval is expected in 2027. Everything below reflects Phase 2 and Phase 3 trial protocols and community experience. For a cross-referenced overview of the retatrutide dosage protocol with reconstitution and syringe-unit tables maintained separately, the PeptideDosage protocol hub is a useful complement.

Phase 2 vs Phase 3 Protocol: What Changed?

Most dosage charts online only show the Phase 2 protocol. Phase 3 (TRIUMPH) uses a slower start and higher ceiling. Both are worth knowing.

Parameter	Phase 2 Protocol	Phase 3 TRIUMPH Protocol
Starting dose	2mg/week	0.5mg/week
Escalation interval	Every 4 weeks	Every 4 weeks
Dose steps	2 → 4 → 8 → 12mg	0.5 → 1 → 2 → 3 → 4 → 5 → 8 → 10 → 12 → 15mg
Maximum dose	12mg/week	15mg/week
Duration to max	~12 weeks	~36–40 weeks
Recommended for	Experienced GLP-1 users	New users, GI-sensitive individuals
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Honestly, most community protocols split the difference — starting at 1mg and escalating every 4 weeks at a pace somewhere between the two. The key principle is the same regardless: slow escalation dramatically reduces GI side effects.

What Indication Is Retatrutide Being Developed For?

Retatrutide is an investigational drug developed primarily for chronic weight management in obesity, and it is not FDA-approved for any use. The landmark Phase 2 trial enrolled adults with a body-mass index of 30 or higher, or a BMI of 27 to under 30 plus at least one weight-related condition (without diabetes), and these obesity-trial criteria are the context behind the body-weight discussion later on this page.

Retatrutide Starting Dose Chart

The retatrutide starting dose is 0.5mg, 1mg, or 2mg per week depending on which protocol you follow and your prior GLP-1 history. Hold the starting dose for a full 4 weeks before any escalation — this is non-negotiable and the #1 cause of avoidable GI side effects when ignored.

Starting Dose	Protocol	Who Should Use It	First Escalation	Hold Period
0.5mg/week	Phase 3 TRIUMPH (conservative)	New to GLP-1 class compounds; GI-sensitive; first-time peptide users	→ 1.0mg/week at week 5	4 weeks at 0.5mg
1.0mg/week	Hybrid community standard	Some semaglutide or tirzepatide history; moderate GI tolerance	→ 2.0mg/week at week 5	4 weeks at 1.0mg
2.0mg/week	Phase 2 (aggressive)	Experienced GLP-1 users (≥6 months semaglutide or tirzepatide); high tolerance	→ 4.0mg/week at week 5	4 weeks at 2.0mg

Choosing the Right Retatrutide Starting Dose

If you're new to the GLP-1 class entirely, start at 0.5mg/week. The week-1 GI hit at 2mg without prior tolerance is the most common reason people quit retatrutide. The slower TRIUMPH ramp adds months to the protocol but dramatically reduces dropout.

If you're stepping over from tirzepatide 5–10mg or semaglutide 1–2.4mg with no major side effects in the last 8 weeks, 2mg/week is reasonable. Your GI tract is already adapted to incretin slowing.

If you're in between — some GLP-1 history but you remember nausea on titration — start at 1mg/week. Splitting the difference is what most community protocols actually do.

What "Starting Dose" Doesn't Mean

The starting dose is not your maintenance dose. The therapeutic weight-loss range is 8–12mg/week, reached after 12–40 weeks of titration depending on protocol. Starting low and escalating slowly is how you get to the therapeutic dose without dropping out — not a permanent dose.

Retatrutide Week-by-Week Dosage Chart (Weeks 1–24+)

This is the table most people come here for. Two protocols side by side. Use the Phase 2 column if you've used semaglutide or tirzepatide before. Use the TRIUMPH column if this is your first GLP-1 class compound or you're GI-sensitive.

Week	Phase 2 Dose	TRIUMPH Dose	Phase Name	Expected Effect
1–4	2mg	0.5mg	Initiation	Minimal weight loss; GI adaptation; appetite change by days 2–3
5–8	4mg	1.0mg	Early escalation	First noticeable appetite suppression; 2–5 lbs typical loss
9–12	8mg	2.0mg	Therapeutic range (P2) / continued escalation (P3)	P2: significant suppression; P3: still building tolerance
13–16	12mg (or hold 8)	3.0mg	Maintenance entry (P2) / mid-escalation (P3)	P2: maximum effect; P3: therapeutic range approaching
17–20	12mg	4.0mg	Maintenance	P3: first real therapeutic dose
21–24	12mg	5.0mg	Maintenance	P3: comparable to P2 week 5–8 effect
25–28	12mg or taper	8.0mg	Maintenance / P3 therapeutic	P3: significant suppression begins
29–32	—	10.0mg	P3 high range	Maximum therapeutic benefit for most users
33–36	—	12.0mg	P3 advanced	Approaching maximum studied dose
37–40+	—	15.0mg	P3 maximum	Only if 10–12mg plateau and tolerated

When to Pause Escalation

Do not increase your dose if any of these are happening:

Nausea persisting more than 3 days post-injection
Vomiting more than twice in a week
Rapid weight loss above 3–4 lbs/week for 2+ consecutive weeks
Severe constipation or diarrhea
Signs of dehydration

Stay at your current dose for an additional 4 weeks. If side effects resolve, escalate. If not, consider dropping back one tier.

Missed Dose Protocol

This is missing from almost every chart online. Here's what the trial data supports:

Missed dose < 4 days ago: Inject as soon as you remember. Resume your regular weekly day.
Missed dose 4–7 days ago: Skip the missed dose. Take your next scheduled dose on the regular day.
Missed dose > 7 days ago: Restart at your previous lower dose tier for 2 weeks before resuming your current dose.

Do not double-dose under any circumstances.

Dose by Vial Concentration: Draw Volume Reference

This is where errors happen. The same 4mg dose requires completely different syringe volumes depending on how you reconstituted your vial. These tables cover the four most common setups. If you're reconstituting differently, use the formula: Volume (mL) = Target Dose (mg) ÷ Concentration (mg/mL).

10mg Vial — Common Reconstitution Options

Reconstitution	Concentration	2mg dose	4mg dose	8mg dose	12mg dose
10mg + 1mL BW	10mg/mL	0.20 mL	0.40 mL	0.80 mL	1.20 mL*
10mg + 2mL BW	5mg/mL	0.40 mL	0.80 mL	1.60 mL*	2.40 mL*
10mg + 4mL BW	2.5mg/mL	0.80 mL	1.60 mL*	3.20 mL*	—

*Volumes over 1mL may require split injection into two sites. Preferred max single-site volume is 1mL.

5mg Vial — Conservative Start Protocol

Reconstitution	Concentration	0.5mg dose	1mg dose	2mg dose	4mg dose
5mg + 1mL BW	5mg/mL	0.10 mL	0.20 mL	0.40 mL	0.80 mL
5mg + 2mL BW	2.5mg/mL	0.20 mL	0.40 mL	0.80 mL	1.60 mL*

5mg vials are best for the initiation phase if you're going with the TRIUMPH protocol — they'll get you through weeks 1–8 on the 0.5mg/1mg schedule without waste.

Unit Conversion Table: mg to mcg to Insulin Syringe Units

People trip on this constantly. Milligrams, micrograms, and insulin syringe units are three different scales. Here's the complete conversion reference for retatrutide's dosing range.

Dose (mg)	Dose (mcg)	Volume at 5mg/mL (mL)	U-100 Syringe Units	Volume at 10mg/mL (mL)	U-100 Syringe Units
0.5mg	500mcg	0.10 mL	10 units	0.05 mL	5 units
1.0mg	1,000mcg	0.20 mL	20 units	0.10 mL	10 units
2.0mg	2,000mcg	0.40 mL	40 units	0.20 mL	20 units
3.0mg	3,000mcg	0.60 mL	60 units	0.30 mL	30 units
4.0mg	4,000mcg	0.80 mL	80 units	0.40 mL	40 units
5.0mg	5,000mcg	1.00 mL	100 units	0.50 mL	50 units
8.0mg	8,000mcg	1.60 mL*	160 units*	0.80 mL	80 units
10.0mg	10,000mcg	2.00 mL*	200 units*	1.00 mL	100 units
12.0mg	12,000mcg	2.40 mL*	240 units*	1.20 mL*	120 units*
15.0mg	15,000mcg	3.00 mL*	300 units*	1.50 mL*	150 units*

*Split into two injection sites if volume exceeds 1mL.

How to read this: U-100 insulin syringes have markings from 10–100 units, where 100 units = 1.00 mL. A 10mg/mL concentration at 4mg requires 0.40mL = 40 units on the syringe. Simple once you get it. Draw to the 40-unit mark, not 0.40 on the barrel — your syringe probably only shows unit markings, not mL.

Retatrutide vs Tirzepatide vs Semaglutide: Dosage Comparison Chart

People ask this all the time. Here's how the three leading GLP-1 class compounds compare side by side on dosing parameters and clinical outcomes.

Parameter	Retatrutide	Semaglutide (Ozempic/Wegovy)	Tirzepatide (Mounjaro/Zepbound)
Receptor targets	GLP-1 + GIP + Glucagon	GLP-1 only	GLP-1 + GIP
Starting dose	0.5–2mg/week	0.25mg/week	2.5mg/week
Maximum studied dose	15mg/week	2.4mg/week	15mg/week
Escalation interval	Every 4 weeks	Every 4 weeks	Every 4 weeks
Time to max dose	12–40 weeks	16 weeks	20 weeks
Half-life	~6 days	~7 days	~5 days
Best weight loss (48–68 weeks)	24.2–28.7%	~15–17%	~20–22%
FDA approval status	Phase 3 / Expected 2027	Approved (Wegovy 2.4mg)	Approved (Zepbound 15mg)
Route	Subcutaneous injection	Subcutaneous injection	Subcutaneous injection
Frequency	Once weekly	Once weekly	Once weekly

The weight loss edge for retatrutide is real and consistent across trials — roughly 4–8 percentage points better than tirzepatide, and 10–13 points better than semaglutide. That gap widens further at the 68-week mark.

Retatrutide and Blood Sugar: Dosing Context for Type 2 Diabetes

Beyond the obesity program, retatrutide was also studied in a separate Phase 2 trial in people with type 2 diabetes, where it showed glucose-lowering as well as weight-lowering effects across a range of doses. Because the glucagon-receptor arm is what sets retatrutide apart from semaglutide and tirzepatide and can influence glycemic markers, anyone with type 2 diabetes or prediabetes should discuss dose escalation and glucose monitoring with their care team rather than self-managing it. This is trial-context information only; retatrutide is not FDA-approved as a diabetes treatment.

Retatrutide Dosage for Adults Chart: Body Weight Context

Here's something almost no dosage chart for adults addresses: should a 180-pound person and a 350-pound person follow the exact same titration? Honestly, probably not — though the trials didn't stratify dosing by bodyweight in Phase 2.

What the data shows: dose-dependent response is steep. The jump from 4mg to 8mg produces roughly 6–8 additional percentage points of weight loss. The jump from 8mg to 12mg adds another 4–5 points. Staying at 8mg is reasonable if you're already losing 1–2 lbs/week with manageable side effects. See our full retatrutide dosage guide for individualized protocol guidance.

Dose Decision Framework by Response

Current Dose	Response at Week 4	Recommendation
2mg	Losing <1 lb/week, mild GI	Escalate to 4mg on schedule
2mg	Losing <1 lb/week, severe GI	Hold 4 more weeks at 2mg
4mg	Losing 1–2 lbs/week	Escalate per schedule
4mg	Losing 2+ lbs/week, GI rough	Hold at 4mg — consider 4mg as maintenance
8mg	Weight loss plateau 3+ weeks	Escalate to 12mg
8mg	Losing 1+ lb/week, manageable	Consider 8mg as maintenance — no need to push to 12mg
12mg	Intolerable GI effects	Drop back to 8mg for 4–8 weeks, retry escalation

GI Side Effect Rates by Dose Tier

This data from Phase 2 trials fills a gap almost no other chart covers. These are approximate rates from the NEJM Phase 2 publication:

Dose (mg/week)	Nausea (%)	Vomiting (%)	Diarrhea (%)	Constipation (%)
2mg	~15%	~5%	~12%	~8%
4mg	~30%	~10%	~18%	~12%
8mg	~45%	~20%	~22%	~15%
12mg	~55%	~25%	~25%	~18%
Placebo	~16%	~4%	~13%	~7%

Key insight: most GI effects are transient. They peak in weeks 1–2 at each new dose tier and typically resolve by week 3–4. Slow titration — not dose reduction — is the primary management tool.

For a detailed breakdown of side effect management strategies, see our retatrutide side effects guide.

How to Inject Retatrutide: Dose Administration Basics

The dosage chart is only useful if the administration is right. Short version:

Site: Subcutaneous injection — abdomen (2 inches from navel), upper thigh, or outer upper arm
Rotation: Rotate injection sites weekly to prevent lipodystrophy
Temperature: Remove from refrigerator 15–20 minutes before injecting
Pinch: Pinch 1–2 inches of skin, inject at 45–90 degrees
Day: Same day every week — set a recurring calendar reminder

Full step-by-step injection protocol including reconstitution is covered in our retatrutide injection guide.

Storage and Reconstitution Quick Reference

Condition	Lyophilized (powder)	Reconstituted (liquid)
Temperature	Store at room temp or refrigerate	Refrigerate at 2–8°C
Shelf life	12–24 months (sealed)	28–30 days after reconstitution
Light sensitivity	Keep away from direct light	Keep away from direct light
Freeze?	Avoid repeated freeze-thaw	Do not freeze

Retatrutide Dosage Calculator: Manual Method

No interactive tool here — just the math you need to run it yourself:

Formula: Volume (mL) = Target Dose (mg) / Concentration (mg/mL)

Concentration formula: Concentration (mg/mL) = Vial Size (mg) / Bacteriostatic Water Added (mL)

Example: 10mg vial + 2mL bacteriostatic water = 5mg/mL. Target dose = 8mg. Volume = 8 / 5 = 1.6mL. Split into two 0.8mL injections.

U-100 syringe conversion: Units = Volume (mL) x 100

So 0.8mL = 80 units. 0.4mL = 40 units.

Run this calculation before every single injection at a new dose tier. Errors compound across a protocol.

Where to Source Retatrutide

Retatrutide is currently not FDA-approved. Availability is through research supply vendors with third-party lab verification. Always verify:

HPLC testing certificate (purity ≥98%)
Certificate of Analysis from independent lab
Batch-specific documentation

Recommended source: Ascension Peptides — lab-verified supply, ships promptly.

Frequently Asked Questions

What is the starting dose for retatrutide?

The starting dose is either 2mg/week (Phase 2 protocol, used for experienced GLP-1 users) or 0.5mg/week (Phase 3 TRIUMPH protocol, used for new users or those sensitive to GI effects). Both are correct — the choice depends on your prior experience. Either way, stick with the starting dose for a full 4 weeks before escalating.

How long does it take to reach the maintenance dose?

Using the Phase 2 protocol (2mg start), you reach 12mg in approximately 12–16 weeks. Using the TRIUMPH protocol (0.5mg start), reaching 10–15mg takes 28–40 weeks. The slower approach significantly reduces GI dropout rates. If you're coming from tirzepatide, the Phase 2 ramp is probably fine.

How do I convert my retatrutide dose to insulin syringe units?

Multiply your draw volume in mL by 100 to get U-100 syringe units. First, calculate draw volume: divide your target dose in mg by your concentration in mg/mL. Example: 4mg dose at 5mg/mL concentration = 0.80mL = 80 units on a U-100 syringe. The conversion table above covers every standard dose at both 5mg/mL and 10mg/mL concentrations.

Can I stay at 8mg instead of going to 12mg?

Yes — and this is probably underappreciated in most dosing guides. If you're losing 1+ lb per week at 8mg with manageable side effects, there's no compelling reason to push to 12mg. The Phase 2 data shows roughly 20–22% body weight loss at 8mg over 48 weeks versus 24.2% at 12mg. That extra 2–4% might not be worth harsher GI effects for every user. Maintenance doses are individualized, not fixed.

What happens if I miss a dose?

The recovery depends on timing. If you missed less than 4 days ago, inject as soon as possible and resume your weekly schedule. If it's been 4–7 days, skip the missed dose entirely and take the next one on your regular day. If more than 7 days have passed, drop back to your previous dose tier for 2 weeks before returning to your current dose. Never double-dose to compensate for a missed injection.

How does retatrutide dosage compare to tirzepatide?

Milligram for milligram, retatrutide and tirzepatide have similar dose ranges (both top out around 12–15mg weekly). The key difference is outcome: retatrutide produces roughly 4–8% greater weight loss at comparable doses due to the added glucagon receptor activation. Tirzepatide is FDA-approved; retatrutide is not yet. The titration protocols are nearly identical — 4-week escalation intervals, similar starting doses.

How much bacteriostatic water should I add to reconstitute retatrutide?

The most common approach for a 10mg vial is 2mL of bacteriostatic water, giving a 5mg/mL concentration. This makes dosing math simple: 1mg = 0.20mL, 2mg = 0.40mL, 4mg = 0.80mL. Some prefer 1mL for a 10mg/mL concentration (smaller volumes per injection, useful at higher doses). Avoid diluting too much — very low concentrations mean large injection volumes at therapeutic doses.

What does the retatrutide dosage chart include?

The retatrutide dosage chart on this page covers all three published protocols (Phase 2 fast-ramp, TRIUMPH-1 obesity, TRIUMPH-4 maintenance), starting doses from 0.5mg to 2mg, weekly escalation from week 1 through week 24+, draw volumes for 5mg and 10mg vial concentrations, and U-100 insulin syringe unit conversions. If you searched "dose chart", "dosing chart for retatrutide", or "dosage chart for retatrutide" — it's all the same chart, just different phrasings of the same dosing protocol.

Is there a retatrutide vs tirzepatide dosage chart side by side?

Yes — the comparison table in the "Retatrutide vs Tirzepatide vs Semaglutide" section above places all three peptides side by side at every escalation step. The short version: starting doses run 0.5–2mg for retatrutide vs 2.5mg for tirzepatide, maintenance tops out at 12mg vs 15mg, and 4-week escalation intervals are identical. The dose chart is similar; the outcome diverges because retatrutide adds glucagon receptor activation.

How does the retatrutide peptide dosage chart compare to commercial GLP-1s?

The retatrutide peptide dosage chart runs in the same milligram range as compounded semaglutide and tirzepatide — 0.5mg to 12mg weekly. The functional difference is that retatrutide hits three receptors (GLP-1, GIP, glucagon) while semaglutide hits only one, so per-milligram weight loss is roughly 4–8% higher. Vial concentrations and draw volumes follow the same insulin-syringe logic as other research peptides.

Is there a retatrutide weight loss chart by dose?

The Phase 2 weight loss chart by dose: approximately 8% body weight loss at 1mg, 14–17% at 4mg, 20–22% at 8mg, and 24.2% at 12mg over 48 weeks. The relationship is dose-dependent but not perfectly linear — the gain from 8mg to 12mg is smaller than the gain from 4mg to 8mg, which is why many users hold maintenance at 8mg rather than push to the ceiling dose.

What's the quick-reference retatrutide dose chart for each week?

Week 1–4: starting dose (0.5mg or 2mg). Week 5–8: first escalation (1mg or 4mg). Week 9–12: 2mg or 6mg. Week 13–16: 4mg or 8mg. Week 17–20: 6mg or 10mg. Week 21–24: 8mg or 12mg. The full retatrutide dose chart in the "Week-by-Week" section above includes draw volumes alongside each dose tier.

Is there a retatrutide dosage chart in syringe units?

Yes — see the "Unit Conversion Table" section above. The retatrutide dosage chart in units maps every standard dose (0.5mg, 1mg, 2mg, 4mg, 6mg, 8mg, 10mg, 12mg) to U-100 insulin syringe units at both common concentrations (5mg/mL and 10mg/mL). Shortcut: at 5mg/mL, multiply mg by 20 to get units; at 10mg/mL, multiply mg by 10.

Is "retaglutide dosage for adults" the same as retatrutide?

Yes — "retaglutide" is a common misspelling of retatrutide. Both refer to Eli Lilly's triple-agonist peptide (LY3437943). The retaglutide dosage for adults is the same dosage chart as retatrutide: 0.5mg or 2mg starting dose, 4-week escalation intervals, maintenance typically 6–12mg weekly.

What is the retatrutide dosing schedule week by week?

The retatrutide dosing schedule is once-weekly subcutaneous injection, escalating every 4 weeks. The full week-by-week table is in the "Week-by-Week Dosage Chart" section above. What is the dosing schedule for retatrutide in one sentence: hold each dose for 4 weeks before escalating, never skip a step, pause escalation if GI side effects exceed your tolerance, and stop escalating when continued weight loss is acceptable at a tolerable side-effect level.

Is there a retatrutide dosage chart PDF I can download?

No retatrutide dosage chart PDF is published at this time. The chart on this page is built to be readable on mobile and desktop without download. If you need a portable version, screenshotting the "Week-by-Week Dosage Chart" and "Unit Conversion Table" sections captures the same information a PDF would.

Is the GLP-3 retatrutide dosage chart different from regular retatrutide?

No — "GLP-3" is an informal nickname for retatrutide because it acts on three receptors (GLP-1, GIP, and glucagon), making it a triple agonist rather than a single GLP-1 agonist. The GLP-3 retatrutide dosage chart is the same dosage chart as retatrutide: same molecule (LY3437943), same protocol, same escalation intervals.

What is a 0.1mg retatrutide dose in syringe units?

A 0.1mg retatrutide dose is 2 units on a U-100 insulin syringe at 5mg/mL concentration, or 1 unit at 10mg/mL concentration. Note: 0.1mg is far below any clinical retatrutide dose — the smallest standard starting dose is 0.5mg. If you're calculating 0.1mg dose in units for microdosing purposes, double-check your math, because at 5mg/mL it's only 0.02mL of solution, which is hard to draw accurately.

The information on this page is based on published Phase 2 and Phase 3 clinical trial data and is provided for educational purposes. Retatrutide is not FDA-approved. Consult a licensed healthcare provider before beginning any peptide protocol. Individual responses to dosing vary significantly.

Retatrutide Dosage Chart: Week-by-Week Schedule