Mounjaro and Wegovy at Christmas: Should You Skip or Pause a Dose?

For most people, the best plan is to carry on injecting over Christmas. If the day is awkward, you can move it by a day or two. You can also ask your prescriber whether a planned dose increase should wait. Skipping a single week will not undo your progress, but a long pause is a different matter.

This article covers the once-weekly injection pens: Mounjaro and Wegovy. The weekly missed-dose, day-shifting and pen-storage rules below do not apply to daily medicines such as Wegovy tablets or Foundayo. If you take a daily medicine, follow the leaflet in your box and ask your prescriber what to do if you miss a dose.

Moving a dose is better than skipping it#

Mounjaro (tirzepatide) and Wegovy (semaglutide) injection pens are both used once a week. The UK leaflets say you can change your injection day, as long as there are at least 3 days (72 hours) between two doses.

Say your usual day is Christmas Day. You could take it a day or two early or late, then stay on the new day. You do not need to change anything else.

If you are due to step up to a higher dose in Christmas week, ask your prescriber whether to step up as planned or stay on your current dose for longer. This is a decision for your prescriber, based on your dose and how you are coping with treatment. A new dose often brings more nausea and reflux, which is a poor match for a rich dinner or a long journey.

Missed dose windows#

These come from the UK product information. Check your own leaflet too.

Never take two doses close together to "catch up". If you cannot remember whether you injected this week, do not guess. Check your calendar or app. If you still cannot tell, ask your prescriber or pharmacist before injecting.

If the gap is 2 weeks or longer#

The leaflets give exact rules for one missed dose. After that, it is down to your prescriber. After 2 or more missed doses, many prescribers restart at a lower dose. This is more likely if you are on a high dose. The reason is simple: your body gets used to the medicine, and a full dose after a break can cause strong nausea and vomiting.

So do not restart at your old dose on your own. Message your prescriber and tell them how many doses you missed.

What pausing does to your weight#

The stone-in-a-few-days claim does not hold up. A stone is about 6.3kg. Gaining that much fat would take roughly 46,000 extra calories. Most people cannot eat that in a few days.

What you may see on the scales after a big meal is 1 to 2kg. That is mostly food still in your gut, salt and water. It settles within days.

The real risk is a long break. In the STEP 1 extension study, people who stopped semaglutide regained about two thirds of the weight they had lost within a year. In SURMOUNT-4, people who switched from tirzepatide to placebo regained about 14% of their body weight over 52 weeks. People who stayed on it kept losing.

One skipped week is small by comparison. The medicines stay in your body for days, so the effect fades slowly.

Pens, deliveries and bank holidays#

GP surgeries and most pharmacies close on 25 and 26 December and 1 January. Scotland also has 2 January. Substitute days apply when these fall at a weekend.

Check your current pen. Count how many doses you have left, then add a spare week. Order your next supply well before the last working days of December. Check your provider's last order and delivery dates, because couriers are slower over the holidays.

If you buy privately, only use a GPhC-registered pharmacy. Fake and unlicensed weight loss jabs are sold online. NHS patients can still call NHS 111 for advice when the surgery is shut. If you take a medicine from Totiva, you can find our weight loss service here.

Travelling with your pens#

Check these figures against the leaflet in your box.

• Keep pens in your hand luggage. The hold can get cold enough to freeze them, and a frozen pen must be thrown away.
• Carry a letter or prescription label from your prescriber. Airport security usually allows injectable medicines and needles, but staff may ask.
• Keep the pen in its carton with the cap on, away from heat and sunlight.
• If you cross time zones, inject when it suits your new day, as long as you leave at least 3 days since the last dose.
• Take travel insurance, and a GHIC for the EU, in case you need care abroad.

Eating and drinking at Christmas on a jab#

These medicines slow how fast your stomach empties. Rich, fatty food and big portions are what tend to cause nausea, reflux and bloating.

• Start with a small plate and wait 15 to 20 minutes before seconds.
• Eat the foods you love and leave the ones you do not. Skipping the pigs in blankets is easier than skipping the whole meal.
• Do not save up calories by not eating all day. Under-eating then overeating tends to make you feel worse.
• Drink water between festive drinks.

The UK advice is to keep to 14 units a week or fewer. A large glass of mulled wine can be 3 units. Heavy drinking also raises the risk of pancreatitis. If you also take insulin or a sulfonylurea for diabetes, alcohol can cause low blood sugar, so ask your diabetes team for advice before the party season.

Get urgent help if you have severe, constant stomach pain that spreads to your back, with or without vomiting. Do not take your next dose. Call 999 or go to A&E. This can be a sign of pancreatitis. Report any side effects through the MHRA Yellow Card scheme.

If you are ill, or use the pill#

If you are vomiting or have diarrhoea, drink small, frequent sips of fluid. Dehydration can harm your kidneys, and being sick is no time to take a higher dose. If you cannot keep fluids down for more than a day, speak to a clinician. You may need to delay your injection.

If you take metformin, an SGLT2 inhibitor, an ACE inhibitor or a diuretic, ask your prescriber, GP or pharmacist about sick-day rules. Some of these medicines may need to be paused while you are dehydrated, but do not stop any of them without advice.

Mounjaro can make the contraceptive pill less effective. Use a barrier method such as condoms for 4 weeks after you start and after every dose increase. Vomiting or severe diarrhoea can also stop the pill working, so use extra protection until you have been well for a week.

If food has become something to fear#

Some people use these medicines to stop eating, or swing between strict days and big binges. That pattern is not what the medicine is for. Food at Christmas is part of life.

If you recognise it, speak to your prescriber or GP. The eating disorder charity Beat offers free support on 0808 801 0677.

If Christmas week is coming up, message your prescriber now. Ask about your dose day, your next order and any planned dose increase.