# Your first weeks on a GLP-1

> Every leaflet and label here starts on a low dose for about a month before the first step up. Mounjaro’s says feeling sick, diarrhoea and being sick are most common when first starting, and decrease over time in most patients. Wegovy’s and Ozempic’s say learn the pen from your doctor or nurse first.

Canonical: https://jabwise.app/guides/your-first-weeks. Sources checked 12 October 2026. General information, not medical advice: follow your prescriber.

## Starting doses

Each source’s first dose, quoted as written. Rybelsus’s older tablets start on 3mg and its newer ones on 1.5mg, each for one month before the first step up.

- **Mounjaro**: Starts on: "The starting dose is 2.5 mg once a week for four weeks." ([Mounjaro KwikPen patient leaflet](https://www.medicines.org.uk/emc/product/15481/pil))
- **Zepbound**: Starts on: "The recommended starting dosage is 2.5 mg injected subcutaneously once weekly for 4 weeks." ([Zepbound prescribing information](https://uspl.lilly.com/zepbound/zepbound.html))
- **Wegovy**: Starts on: "When you first start using wegovy®, the starting dose is 0.25 mg once weekly." ([Wegovy FlexTouch patient leaflet](https://www.medicines.org.uk/emc/product/13800/pil))
- **Ozempic**: Starts on: "The starting dose is 0.25 mg once a week for four weeks." ([Ozempic patient leaflet](https://www.medicines.org.uk/emc/product/9748/pil))
- **Rybelsus**: Starts on: "The starting dose is one 3 mg tablet once a day for one month." ([Rybelsus 3, 7 and 14mg patient leaflet](https://www.medicines.org.uk/emc/product/11507/pil))

## Early on

- **Stomach side effects**: Mounjaro’s leaflet says feeling sick, diarrhoea and being sick are most common at first, then ease in most patients.
- **Fluids**: When starting Mounjaro, its leaflet says, some people lose fluids; it says drink plenty of fluids to avoid dehydration.
- **Dizziness**: Wegovy’s leaflet says some people feel dizzy, mainly in the first 3 months, and not to drive until they feel better.
- **Contraception**: On tirzepatide, the NHS says use extra barrier contraception, like condoms, for 4 weeks after starting and each increase.

## Before the first jab

- **Learning the pen**: Wegovy’s and Ozempic’s leaflets say your doctor or nurse will show you, or to ask them.
- **What to raise first**: The leaflets list things to tell your doctor first, such as pancreatitis or a slow-emptying stomach.
- **The same day each week**: Mounjaro, Wegovy and Ozempic ask for the same day each week, where you can.
- **New pens in the fridge**: Mounjaro’s, Wegovy’s and Ozempic’s leaflets say keep new pens in the fridge, at 2 to 8°C, never frozen.

## Questions

### Will the side effects last?

Mounjaro’s leaflet says feeling sick, diarrhoea and being sick decrease over time in most patients, and Ozempic’s says feeling sick and diarrhoea usually go away. None gives a timescale.

### How long until the level settles?

Mounjaro’s product information says after 4 weeks of weekly doses, and Ozempic’s says 4 to 5. Our guide to how a weekly jab builds up shows it.

### What if I miss a dose?

Mounjaro’s leaflet and Zepbound’s label say use it within 4 days, Wegovy’s and Ozempic’s within 5, and otherwise skip it. None covers a missed first dose; your prescriber can advise.

## In Jabwise: Mood trends

See how your first weeks feel. Check in morning, afternoon or evening. Mood shows the answer you log most over 7, 30 or 90 days, and once one part of the day leads, when you feel best.

## Getting real advice

- **A pharmacist, your doctor or NHS 111**: If you’re not sure how to use your medicine, or a side effect bothers you or won’t go away. NHS 111 if you think you might be having serious side effects, or you’ve used too much. [NHS: Semaglutide](https://www.nhs.uk/medicines/semaglutide/), [NHS: Tirzepatide](https://www.nhs.uk/medicines/tirzepatide/), [NHS 111 online](https://111.nhs.uk/)
- **Report a side effect**: Anyone can, not only doctors. [Yellow Card (UK)](https://yellowcard.mhra.gov.uk/), [MedWatch (US)](https://www.fda.gov/safety/medwatch-fda-safety-information-and-adverse-event-reporting-program)

## Sources

- [Mounjaro KwikPen patient leaflet](https://www.medicines.org.uk/emc/product/15481/pil)
- [Zepbound prescribing information](https://uspl.lilly.com/zepbound/zepbound.html)
- [Wegovy FlexTouch patient leaflet](https://www.medicines.org.uk/emc/product/13800/pil)
- [Ozempic patient leaflet](https://www.medicines.org.uk/emc/product/9748/pil)
- [Rybelsus 3, 7 and 14mg patient leaflet](https://www.medicines.org.uk/emc/product/11507/pil)
- [Rybelsus 1.5, 4 and 9mg patient leaflet](https://www.medicines.org.uk/emc/product/101229/pil)
- [Mounjaro product information (SmPC)](https://www.medicines.org.uk/emc/product/15481/smpc)
- [Ozempic product information (SmPC)](https://www.medicines.org.uk/emc/product/9750/smpc)
- [NHS: Semaglutide](https://www.nhs.uk/medicines/semaglutide/)
- [NHS: Tirzepatide](https://www.nhs.uk/medicines/tirzepatide/)