Retatrutide (20 mg Vial) Dosage Protocol

Triple-agonist peptide for substantial weight loss and metabolic health.

Dose range
2-12 mg weekly
Route
Subcutaneous
Frequency
Once weekly
Cycle length
12-48 weeks

Retatrutide is a triple-agonist peptide used in educational protocols for significant weight loss and metabolic improvements. It is dosed once weekly via subcutaneous injection, starting at a low dose and gradually increasing over several weeks to minimize potential side effects.

  • Triple-agonist targeting GLP-1, GIP, and glucagon receptors.
  • Leads to significant weight loss (up to 24%) and improved glycemic control.
  • Administered once weekly via subcutaneous injection.
  • Dose escalation is critical to minimize gastrointestinal side effects.
  • Not FDA-approved; currently for research and educational use only.

Reconstitution

Vial strength

20 mg

Bacteriostatic water

2 mL

Concentration

10 mg/mL

1 unit = 0.01 mL = 100 mcg

  1. 1Draw 2.0 mL bacteriostatic water with a sterile syringe.
  2. 2Inject slowly down the vial wall; avoid foaming.
  3. 3Gently swirl/roll until dissolved (do not shake).
  4. 4Label with date and refrigerate at 2–8 °C (35.6–46.4 °F), protected from light.
  5. 5Use within 4 weeks of reconstitution.

Dosing schedule

PhaseDoseOn a U-100 syringe
Weeks 1–42 mg20 units (0.20 mL)
Weeks 5–84 mg40 units (0.40 mL)
Weeks 9–126 mg60 units (0.60 mL)
Weeks 13+8 mg80 units (0.80 mL)

Protocol detail

Start2 mg weekly for 4 weeks to assess tolerance.
EscalateIncrease by 2–4 mg every 4 weeks as tolerated.
Target6–8 mg weekly (standard); 12 mg weekly (advanced/aggressive).
FrequencyOnce per week (subcutaneous), same day each week.
Cycle LengthMinimum 24 weeks; trials extended to 48 weeks.
TimingAny consistent day/time; rotate injection sites with each dose.

Overview at a glance

GoalSupport significant weight reduction and metabolic improvements through triple-receptor activation.
ScheduleWeekly subcutaneous injections for 12–48 weeks.
Dose Range2–12 mg weekly with gradual 4-week titration steps.
Reconstitution2.0 mL per 20 mg vial (~10.0 mg/mL).
StorageLyophilized frozen at −20 °C; reconstituted refrigerated at 2–8 °C for up to 4 weeks.

How it works

Retatrutide functions as a triple-agonist, simultaneously activating GLP-1, GIP, and glucagon receptors. This multi-pronged approach enhances insulin secretion in the presence of glucose and curbs appetite, similar to GLP-1/GIP therapies. Unique to Retatrutide, glucagon receptor activation also boosts metabolic rate and energy expenditure, further promoting fat loss and countering the body's metabolic slowdown often seen during weight reduction. Its extended half-life, due to a fatty-acid modification, permits convenient once-weekly dosing. This combined hormonal action leads to decreased calorie intake, increased satiety, improved fat oxidation, potent weight loss, and better glycemic control.

Reported effects

  • Exceptional weight loss (up to 24% body weight)
  • Significant glycemic control (HbA1c reductions)
  • Cardiometabolic improvements (reduced blood pressure, LDL, waist circumference)
  • Effective resolution of liver fat content (hepatic steatosis)
  • High response rate, with 100% achieving at least 5% weight reduction

Reported side effects

  • Mild-to-moderate gastrointestinal symptoms (nausea, vomiting, diarrhea)
  • Side effects are dose-dependent and typically transient
  • Primarily occur during dose escalation
  • Severity is minimized with gradual titration schedules

Storage

Lyophilised (unmixed)

Freeze at -20 °C (-4 °F) or colder in dry, dark conditions; stable for up to 24 months.

After reconstitution

Refrigerate at 2–8 °C (35.6–46.4 °F) for up to 4 weeks. Can be aliquoted and frozen at -20 °C for extended storage (thaw only once).

Supplies

Peptide vialsRetatrutide (20 mg each): 3 vials for 12 weeks (standard to 6mg); 8 vials for 24 weeks (standard to 8mg).
Insulin SyringesU-100, 1 mL capacity: 1-2 syringes per week (12-24 for 12 weeks; 24-48 for 24 weeks).
Bacteriostatic Water10 mL bottles: ~2.0 mL per vial for reconstitution. (1x10mL bottle for 12 weeks; 2x10mL bottles for 24 weeks).
Alcohol Swabs2-4 swabs per week (approx. 50 per 12 weeks; 100 per 24 weeks).

Important notes

  • Use a new sterile insulin syringe for each injection and dispose of it properly.
  • Rotate injection sites (abdomen, thighs, upper arms) to minimize irritation.
  • For injection volumes over 1.0 mL, split into two separate injections at different sites.
  • Inject slowly and gently to ensure full dose delivery.
  • Document weekly doses and injection sites for consistency.
  • Gradual titration is essential to reduce gastrointestinal side effects.

Frequently asked questions

What makes Retatrutide different from other weight loss peptides?

Retatrutide is a triple-agonist, meaning it activates three different receptors (GLP-1, GIP, and glucagon). This unique combination allows it to significantly suppress appetite, enhance insulin secretion, and boost metabolism more effectively than peptides that target only one or two pathways, leading to superior weight loss and metabolic benefits identified in research.

How crucial is the titration schedule for Retatrutide?

Titration is very crucial. Starting with a low dose and gradually increasing it over several weeks (typically 4-week intervals) is essential to help the body adjust and minimize common gastrointestinal side effects like nausea and vomiting. Skipping these gradual escalation steps can lead to more severe discomfort.

What are the common storage guidelines for Retatrutide before and after reconstitution?

Before reconstitution, lyophilized Retatrutide should be stored frozen at -20 °C (-4 °F) or colder, in a dry and dark environment. After reconstitution with bacteriostatic water, the solution must be refrigerated at 2-8 °C (35.6-46.4 °F) and used within 4 weeks. For longer storage of the reconstituted solution, it can be aliquoted and frozen, but should only be thawed once before use.

Can I split a high-volume Retatrutide injection into multiple sites?

Yes, for injection volumes exceeding 1.0 mL, it is recommended to split the dose into two separate subcutaneous injections at different sites. This practice helps ensure proper absorption and can minimize discomfort or irritation at the injection site.

Educational reference only. These figures summarise how Retatrutide is commonly described in research literature and supplier documentation, including the Retatrutide listing at peptidesuk4u.co.uk. They are not a prescription, not medical advice, and not a recommendation to self-administer anything.

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