DOSING & TITRATION
GLP-1 Dosing and Titration — Schedules, Reconstitution, and Reading the Syringe
By G1 Peptides · Medically reviewed by the G1 Peptides clinical team · Updated September 24, 2026 · 3 min read
THE SHORT ANSWER
All three major GLP-1 drugs are injected once weekly and escalated in steps held for about four weeks each — semaglutide 0.25 → 2.4 mg, tirzepatide 2.5 → 15 mg, retatrutide 1 → 12 mg. Compounded versions are lyophilized vials dosed in milligrams; the water you add sets the mg per mL, and a calculator converts each step to syringe units.
The schedules
Each step is typically held for four weeks before increasing; a provider can hold longer if side effects are active.
Semaglutide (labelled schedule): 0.25 mg → 0.5 mg → 1 mg → 1.7 mg → 2.4 mg weekly. Sixteen weeks to reach the maintenance dose.
Tirzepatide (labelled schedule): 2.5 mg → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mg weekly, each step optional; the 5 mg and 10 mg steps are common maintenance doses (SURMOUNT-1).
Retatrutide (trial-based): 1 mg → 2 mg → 4 mg → 8 mg → 12 mg weekly, with the pace set by tolerance. Many people maintain at 4–8 mg.
The first step of each schedule is intentionally too low to cause much weight loss. It is there to let the gut adapt. Skipping it to "get going faster" is the most common cause of severe nausea.
Reconstituting a compounded vial
Compounded GLP-1s arrive as freeze-dried powder. The steps are the same as any peptide — full guide here — with one thing to get right: the water volume sets the concentration, and the concentration decides your syringe units at every step.
Typical choices:
| Vial | Water | Concentration | 0.25 mg | 1 mg | 2.4 mg |
|---|---|---|---|---|---|
| 5 mg semaglutide | 2 mL | 2.5 mg/mL | 10 U | 40 U | 96 U |
| 10 mg tirzepatide | 2 mL | 5 mg/mL | — | 2.5 mg = 50 U | 10 mg = 200 U |
| 10 mg retatrutide | 2 mL | 5 mg/mL | — | 1 mg = 20 U | 8 mg = 160 U |
Notice the high steps overflow a 100-unit syringe. Solutions: reconstitute in less water (10 mg in 1 mL is 10 mg/mL, so 10 mg of tirzepatide is 100 units), use a larger vial, or split the dose into two injections. Your pharmacy's instructions specify the volume; the calculators show the units for any combination.
Converting a dose to units
concentration (mg/mL) = vial mg ÷ water mL
volume (mL) = dose mg ÷ concentration
units (U-100) = volume × 100
For a 5 mg semaglutide vial in 2 mL at the 0.5 mg step: 2.5 mg/mL → 0.2 mL → 20 units. The semaglutide, tirzepatide, and retatrutide calculators do this live and show doses per vial so you can time refills.
Handling each step
- Start of a step: expect a few days of increased nausea or fullness; eat smaller meals, avoid greasy food, stay hydrated.
- Mid-step: effects fade; appetite suppression stays.
- Before stepping up: if nausea is still daily, hold another two to four weeks rather than escalating.
- Missed dose: take it within about three days (semaglutide: five); otherwise skip and resume on schedule. Never double.
- Long gap (two or more weeks): ask your provider about restarting at a lower step.
Vial life and refills
Reconstituted GLP-1s are commonly usable for 28 days refrigerated — check your label. At low steps a vial lasts many weeks and will expire before it is empty; at high steps it holds only a dose or two. Plan refills around the step you are on, not the vial size.
Next: managing GLP-1 side effects.
FREQUENTLY ASKED
Can I stay on a lower dose if it is working?
Yes. The escalation schedule is a maximum pace, not a requirement. Many people maintain on an intermediate dose; the right dose is the lowest one that gives the result with acceptable side effects.
What day should I inject?
Any day, at any time, with or without food — just keep the same day each week. Some people choose a day when nausea would be least disruptive (a Friday evening, for example).
Does the injection site matter?
Abdomen, thigh, or upper arm all work; absorption is equivalent. Rotate sites week to week.
SOURCES
This article is educational and is not medical advice. Peptides are prescription medications; whether any of them is appropriate for you is a decision for a licensed provider who knows your history.