How does GLP-1 titration work? Semaglutide vs tirzepatide step-up schedules

The two titration schedules, side by side

Both medicines are GLP-1 medications taken as a once-weekly subcutaneous injection, and both follow the same logic: start low, hold for 4 weeks, then increase. The point of titrating is tolerability — nausea and GI side effects are worst when the dose jumps, so a slow climb gives the gut time to adapt. Semaglutide for weight management was studied at a 2.4 mg target in the STEP 1 trial (Wilding et al., NEJM 2021), and tirzepatide at 5, 10 and 15 mg targets in SURMOUNT-1 (Jastreboff et al., NEJM 2022).

The Wegovy escalation in Table 1 of its FDA label runs 0.25, 0.5, 1, 1.7, then 2.4 mg, titrating every 4 weeks. The Zepbound label starts at 2.5 mg for 4 weeks and then increases in 2.5 mg increments — 5, 7.5, 10, 12.5, 15 mg — until the chosen maintenance dose is reached. The 2.5 mg tirzepatide and 0.25 mg semaglutide starting doses are initiation only and are not maintenance doses.

How this is calculated

A titration plan is two pieces of arithmetic stacked together. The first is the calendar: each step lasts 4 weeks, so the week a dose begins is 4 × (step number − 1) + 1. Step 1 begins week 1, step 2 begins week 5, step 3 begins week 9, and so on. That is why Wegovy's 2.4 mg (its fifth value, but fourth increase) lands at week 17, and Zepbound's 15 mg (its sixth value) lands at week 21.

The second piece converts the step's dose into a syringe draw. Prescription pens are pre-set, but compounded vials are dosed by volume, so you divide the dose by the vial concentration to get milliliters, then multiply by 100 for U-100 syringe units:

units = (dose in mg ÷ concentration in mg/mL) × 100

Keep the mass units matched — mg with mg/mL. The dose is what is prescribed; the volume is what you draw, and concentration is the bridge between them. Change the vial strength and the same dose needs a different number of units.

Worked examples for each step

These assume a compounded vial, since that is where the maths actually matters. Pens are pre-dialled. Every example uses units = (mg ÷ mg/mL) × 100.

Planning the calendar and handling slow steps

Map each step to a real date so you know when a vial runs out and when the next strength is needed. If a step is not tolerated, both labels allow staying longer at the current dose before stepping up, and the maintenance dose does not have to be the maximum — many people settle below 15 mg tirzepatide or at 1.7 mg semaglutide. If a weekly dose is missed, follow the missed GLP-1 dose rules rather than doubling up. None of this is medical advice: the pace, the target, and any pause belong to your prescriber.

Once your dates and concentration are set, generate the whole plan at once with the GLP-1 titration calculator, which prints the week-by-week dose and the units to draw for a compounded vial.

So, how does GLP-1 titration work?

GLP-1 titration works by starting at a low dose and stepping up every 4 weeks until you reach your maintenance dose, giving the gut time to adapt and reducing nausea. Semaglutide (Wegovy) follows the path 0.25 → 0.5 → 1 → 1.7 → 2.4 mg, reaching maintenance at week 17; tirzepatide (Zepbound) climbs 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg, reaching its maximum at week 21. To turn any step's dose into the exact syringe units for a compounded vial, use the GLP-1 titration calculator.

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