Short answer: Weekly weight-loss injections (Mounjaro, Ozempic, Wegovy) can be given on any day of the week, but they should be given on the same day each week; the time of day is up to you. Many users prefer Friday or Sunday in case of nausea.

Key takeaways

  • There is no required day; you can choose the fixed day that suits your lifestyle best.
  • If you want to change your dose day, there must be at least 3 days (72 hours) between two doses.
  • For a missed dose, the window depends on the active ingredient: 4 days (96 hours) for tirzepatide (Mounjaro, Zepbound), 5 days for semaglutide (Ozempic, Wegovy). After that, skip the dose and carry on with your usual day.
  • Never take a double dose to make up for a missed one.

Weekly GLP-1 injections are given on the same day every week. You choose the day; the product information does not impose a particular one. The time is also up to you and does not depend on meals. The day can be changed later if needed, but there is a minimum gap that must be left between two injections.

This page is for general information only and does not replace medical advice. The injection day, dose and duration are decisions for your GP or prescriber alone. The patient information leaflet for your own medicine takes priority over the general information on this page.

How should you choose the day?

Medically, no day is better than another. In practice, two things decide it: the day should be easy to remember, and the first day or two, when side effects are most noticeable, should fit around your schedule.

Digestive side effects usually come to the fore in the first days after an injection and after each dose increase. That is why a common choice is to avoid lining them up with a busy working day. This is not medical advice, just what users do day to day.

Can you change the day?

Yes. According to the product information for products containing tirzepatide (Mounjaro, Zepbound), the weekly injection day can be changed when needed; the only condition is that there are at least 3 days (72 hours) between two doses. In other words, when moving to a new day, the two injections must not be brought closer than three days apart.

The weekly day can also be changed with products containing semaglutide; because the conditions vary by product, check your own patient information leaflet and let your GP or prescriber know about the change.

What should I do if I miss a dose?

The answer depends on the active ingredient, and this is one of the most commonly confused points about missed doses.

  • Tirzepatide (Mounjaro, Zepbound): take the missed dose within 4 days (96 hours). If more than four days have passed, skip that dose and take the next one on its usual day.
  • Semaglutide (Ozempic, Wegovy): take the missed dose within 5 days. If more than five days have passed, skip it and go back to your normal schedule.

Never take two doses close together to make up for a missed one. If you have missed doses two weeks in a row, speak to your GP or prescriber.

Same day but a different time?

That is fine. With weekly products, what matters is the gap in days, not the time. Taking a dose in the evening the week after a morning dose is not a problem, as long as the minimum-gap rule between two injections is followed.

Keeping track of the day

In a weekly routine, the hardest part is not remembering the day but remembering what happened last week. Haftra sets up the plan automatically from your first dose, reminds you on your dose day and the day before, and recalculates the calendar when you change the day. It is free, can be used without creating an account and does not suggest doses.

iPhone, iPad and Apple Watch. Free.

Frequently asked questions

Which day should a weight-loss injection be given?

With weekly products there is no set day; you choose the day, provided it is the same day every week. Common choices are to pick a day that is easy to remember and to avoid lining up the side effects of the first two days with a busy schedule.

Can I change my injection day?

With products containing tirzepatide, the injection day can be changed; the condition is that there are at least 3 days (72 hours) between two doses. It can also be changed with products containing semaglutide, but the conditions vary by product, so check your patient information leaflet.

What should I do if I miss a dose?

With tirzepatide (Mounjaro, Zepbound), a missed dose is taken within 4 days (96 hours); after that, it is skipped and the next dose is taken on the usual day. With semaglutide (Ozempic, Wegovy), this window is 5 days. In no case are two doses taken close together to make up.

Should I inject at the same time every week?

No. With weekly products, what matters is the gap in days, not the time. The time is up to you and the injection does not depend on meals.

Sources

  • EMA: Mounjaro (tirzepatide)
  • EMA: Ozempic (semaglutide)
  • EMA: Wegovy (semaglutide)
  • NHS: Obesity treatment
  • MHRA (Medicines and Healthcare products Regulatory Agency)

Last reviewed: 4 August 2026