Missed-dose rules: Ozempic vs Mounjaro vs Wegovy
The labeled "missed dose" guidance is different for every once-weekly GLP-1, even between brands of the same molecule. The rescue window is short for a reason: it's tied to the drug's half-life and the maintained plasma threshold for clinical effect.
The labeled windows
| Brand | Molecule | Half-life | Rescue window | Next scheduled dose |
|---|---|---|---|---|
| Ozempic | Semaglutide | ~165 hours | ≤5 days late → take it | If >5 days, skip; resume next regular dose |
| Wegovy | Semaglutide | ~165 hours | ≤48 hours late → take it | If >48 hours, skip; resume next regular dose |
| Mounjaro | Tirzepatide | ~115 hours | ≤4 days late → take it | If >4 days, skip; resume next regular dose |
| Zepbound | Tirzepatide | ~115 hours | ≤4 days late → take it | If >4 days, skip; resume next regular dose |
Wegovy's tighter 48-hour window is conservative because the maintenance dose (2.4 mg) is higher and the GI effects are more sensitive to plasma swings than at Ozempic's smaller doses.
Why the rescue exists
Semaglutide's half-life is roughly a week, so a one- or two-day delay barely changes the area under the curve. At day 5 you're at about 60% of the original trough plasma level, which is still therapeutic. Past day 5, the next dose would land on a half-empty receptor pool, and the resulting spike — back to a fresh peak — is the source of "first-dose nausea" all over again.
What "skip and resume" actually means
If you blow past the rescue window, you do not double the next dose to catch up. You take one scheduled dose, on the original day of the week. Plasma will recover over the next 4–5 weeks as you titrate up or continue maintenance. Doubling the next dose is the most common dosing error and produces severe nausea and vomiting.
Restart vs continue
After a long gap, the question is whether you keep the current dose or step back down the titration ladder. The rule of thumb:
- Gap ≤ 2 weeks: resume current dose.
- Gap 2–4 weeks: drop one step (e.g., 1.0 → 0.5 mg) for 2–4 weeks, then advance back up.
- Gap > 4 weeks: restart titration from 0.25 mg (semaglutide) or 2.5 mg (tirzepatide). Tolerance has decayed.
See the dedicated post on skipping a semaglutide dose for the longer logic.
Compounded GLP-1s inherit the rule, not the label
A compounded semaglutide vial follows the same 5-day rescue window as Ozempic — the active ingredient is identical. A compounded tirzepatide vial follows Mounjaro's 4-day window. The pharmacy's leaflet may or may not state this; the molecule decides. The exception is compounded products with non-standard concentrations: a 5 mg/mL compounded semaglutide can mean a much smaller volume per dose than the 1.34 mg/mL Ozempic pen, but the half-life and rescue window are still the molecule's.
The injection-day discipline that prevents missed doses
One injection day per week, same evening, same alarm. Switching days drift-style is what leads to most missed doses, not actual life events. If you need to shift the day, do it once — by at least 72 hours forward, never backward — and stay on the new day.
FAQ
Can I move my Ozempic injection day every few weeks?
Yes, but only forward, never backward, and never by less than 72 hours. Moving the day backward effectively double-doses through the rescue window.
What if I forget which day was my last injection?
Default to the latest plausible date — take the next dose 7 days after the date you're sure you injected. Underdosing for one week is benign; double-dosing is not. A logged dose history makes this question rare.
Does the rescue window change with the dose?
No. The rescue window is determined by half-life, which is dose-independent. A person on 2.4 mg has the same 5-day window as one on 0.25 mg — but the consequence of a late dose at 2.4 mg is much more uncomfortable.
I missed two consecutive doses. Restart?
Two consecutive doses missed at any maintenance dose = drop at least one step and re-titrate. Three or more = restart from the bottom.
Related reading
Never lose track of your injection day
Peptide Protocol stores every shot, computes plasma decay between doses, and flags whether a late dose is inside the rescue window or needs a skip.
Get the iPhone app →Informational and educational only. Not medical advice. Consult a licensed clinician before starting, changing, or stopping any peptide protocol. Mentions of investigational, compounded, or research-use peptides are for informational purposes; many such substances are not FDA-approved for human use.