GLP-1 Instructions: How to Take Your Medicine (October 2026)

01 · Start here

Which GLP-1 instructions apply to you?

The instructions that apply are the ones in the leaflet for the exact medicine on your label. Mounjaro (tirzepatide) is a once-weekly injectable prescription medicine made by Eli Lilly, supplied as a pre-filled multi-dose pen (KwikPen).¹ Our Mounjaro instructions for use guide goes through the leaflet step by step.

02 · Weekly pen

How to take a Mounjaro pen

Mounjaro is injected under the skin (subcutaneously) once a week, on the same day each week, at any time of day, with or without food.¹ Licensed injection sites are the stomach area (at least 5cm from the belly button), the front of the thigh, or the back of the upper arm if someone else gives the injection. Rotate the site with each dose. Each KwikPen contains four weekly doses.

You set the dose by turning the dose knob until the dose indicator shows the correct dose in the window. For the full walkthrough see our Mounjaro injection pen instructions and how to use the pen. Needles, a sharps bin and injection guidance come with every order.

Ready to start? You can begin with a free consultation on the Mounjaro pen page, where current prices are shown.

03 · Doses and timing

Dose steps and time of day to inject

Everyone starts Mounjaro on 2.5mg once a week. This starting dose is about letting your body adjust, not about weight loss itself. After at least 4 weeks the dose increases to 5mg, and can then step up by 2.5mg at a minimum of 4-week intervals (7.5mg, 10mg, 12.5mg) up to a maximum of 15mg weekly, depending on how you respond and tolerate it.¹¹ Each strength has its own guide, such as our Mounjaro 5mg pen instructions.

There is no "best" time of day. Mounjaro works the same morning or evening, with or without food, so taking it at night is fine. What matters is the same day each week.¹ Many people choose a weekend morning so early side effects fall on days off.

04 · Missed doses and storage

Missed doses, changing day and storage

If you miss a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time, then carry on with your usual day.¹ If more than 4 days have passed, skip it and take the next one on your normal day. Never take two doses within 3 days of each other. You can change your injection day as long as at least 3 days (72 hours) have passed since your last dose.

Keep Mounjaro pens in a fridge at 2–8°C and never freeze them. Once in use, a pen can be kept out of the fridge at a temperature not above 30°C for up to 30 days after first use, and must then be thrown away. Do not use a pen that has been above 30°C or has been frozen. Keep the cap on to protect it from light.¹³ If an unopened pen has been out of the fridge, check with the pharmacy before using it. Our UK injection guide covers travel as well.

05 · GLP-1 tablets

How to take GLP-1 tablets

Wegovy tablets contain semaglutide and are taken as one tablet once a day. The tablet must be taken on an empty stomach after fasting for at least 8 hours, swallowed whole with a sip of water (up to half a glass, about 120ml), and you then wait at least 30 minutes before eating, drinking or taking other tablets.²⁰ If a dose is missed, skip it and take the next tablet the following day.

Foundayo (orforglipron) can be taken at any time of day, with or without food and without water restrictions; the tablet is swallowed whole. If a dose is missed, take it as soon as possible, but never more than one tablet a day.²¹ Foundayo may make oral contraceptive pills less effective: switch to a non-oral method or add a barrier method for 30 days after starting and for 30 days after each dose increase. Mounjaro can also reduce how well oral contraceptive pills are absorbed: switch to a non-oral method, or add a barrier method such as condoms, for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase. There is no tablet form of Mounjaro.¹ For current Wegovy options see the Wegovy pen page.

06 · Early effects and results

Side effects and how fast results come

Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle.¹ They tend to appear within the first few days after a dose, and again after a dose increase.

Tell your prescriber about any new or lasting symptom, and report suspected side effects through the Yellow Card scheme.¹⁹

Weight loss is gradual by design. The early weeks are an adjustment phase and losses are usually modest, so think in months, not days. Trials measured results at 72 weeks, and your prescriber reviews your response along the way.¹

07 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. Seek immediate medical help for: severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis); pain in the upper right abdomen, fever or yellowing of skin/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion) — your prescriber may need to adjust those medicines.¹