A weekly injection is easy to miss and easy to misremember. The internet answers the question with one rule for the whole drug class, and the labels do not support that. There are four approved injectables here, their missed-dose instructions differ, and the two that share a molecule differ from each other.
Semaglutide has two different rules
The Ozempic label measures forward from the dose that was missed. It instructs administering the drug as soon as possible within 5 days after the missed dose; if more than 5 days have passed, the missed dose is skipped and the next one is given on the regularly scheduled day.[1]
The Wegovy injection label measures backward from the dose that is next. If one dose is missed and the next scheduled dose is more than 2 days away, it instructs administering as soon as possible. If the next scheduled dose is less than 2 days away, it instructs not administering the missed dose and resuming on the regular day.[2]
Both products contain semaglutide. They were approved separately, for different indications, at different dose ranges, and each carries its own labeling. That is why the rule you were given depends on which box the drug came in — the same reason the dose ladders differ between them.
Tirzepatide is four days on both products
Zepbound and Mounjaro agree with each other. Each instructs administering the drug as soon as possible within 4 days — stated as 96 hours — after the missed dose, and skipping it if more than 4 days have passed.[3][4] The regular weekly schedule then resumes either way.
Both tirzepatide labels also permit changing the day of the week, as long as at least 3 days (72 hours) separate two doses. Ozempic permits the same change at a minimum of 2 days (more than 48 hours). Those sentences are not incidental: they are the floor that the missed-dose rules sit on, and they say plainly how close together two injections may fall.
The practical effect is that a late dose usually costs nothing beyond the inconvenience of moving the schedule. A person who injects on Sunday and remembers on Wednesday is inside every one of these windows. The rules only start to bite in the second half of the week, and they bite one day earlier on tirzepatide than on Ozempic.
The window is not simply the half-life
Semaglutide has an elimination half-life of approximately 1 week, and its labeling states the drug remains in the circulation for about 5 weeks after the last dose.[1] Tirzepatide’s elimination half-life is approximately 5 days, reported as 5 to 6 days in patients with overweight or obesity.[3][4]
Read those alongside the windows and the intuition breaks. The molecule that clears faster carries the shorter catch-up window, which is the opposite of what a half-life argument predicts. The windows are dosing instructions rather than pharmacokinetic deductions, and they exist to keep the weekly rhythm intact without letting two doses land on top of each other.
Doubling up appears on none of the four labels
Every one of these products offers exactly two options: give the missed dose inside the window, or skip it and resume. None of them describes making up a missed dose by giving two, and the minimum-interval sentences above are the reason. Two injections separated by less than 72 hours of tirzepatide, or less than 48 hours of Ozempic, sits outside what the labels permit.
The tolerability argument points the same way. Gastrointestinal effects in the pivotal trials were concentrated around dose increases rather than spread evenly through treatment.[5][6] Stacking doses reproduces an increase without gaining anything, and nausea has a shape that makes that a bad trade.
A long gap is a different question from a late dose
One label addresses the longer interruption directly. Wegovy instructs that if 2 or more consecutive doses are missed, dosage escalation should be reinitiated at a lower dosage, to reduce the risk of gastrointestinal adverse reactions.[2] That is a labeled instruction about restarting, and it belongs to a prescriber to apply.
The other three labels carry no equivalent sentence in their missed-dose sections. Absence is not permission to resume at the top of the ladder after a month away; it means the question has no labeled answer and lands on the person who wrote the prescription. Anyone whose plan re-prices at each rung should also read what a second climb costs.
The oral rule is a daily rule
Wegovy tablets are taken once daily, and the missed-dose instruction is correspondingly short: skip the missed dose and take the next dose the following day.[2] A daily product forgives a lapse differently from a weekly one, which is one of the practical differences between the oral options and an injection.
What a compounded vial inherits, and what it does not
None of these four inserts ships with a compounded vial. What arrives is a pharmacy label and whatever instructions the seller chose to write, which may or may not reproduce the window for the molecule inside. The windows above were set for specific approved products at specific strengths, and a compounded preparation is neither.
That makes the missed-dose instruction a fair thing to ask a seller for before the first shipment, alongside the dose the price buys. How forthcoming each one is on questions of that kind is part of what the provider reviews record.
A late dose is a common event with a labeled answer, and the answer depends on the product. Which one applies to a particular vial, and what to do after a gap longer than a week, is a conversation for the prescriber or the dispensing pharmacist rather than a search result.