Missed a Dose of Mounjaro or Wegovy? What to Do

If you are using weight loss injections, there is a good chance that at some point a dose will slip your mind. A busy week, a holiday, a bout of illness or a delayed prescription can all mean your usual injection day comes and goes without your dose. It is one of the most common questions we hear at REX Pharmacy: “I’ve missed my Mounjaro (or Wegovy) dose. What should I do now?”

The good news is that a single missed dose is rarely a cause for alarm. Both Mounjaro and Wegovy have clear, licensed instructions for what to do, and the rules are slightly different for each medicine. This guide walks you through those rules, explains what happens if you have missed more than one dose, and sets out when you may need to restart at a lower dose to stay comfortable and safe.

If you are unsure at any point, please speak to a pharmacist before taking your next dose.

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Why Missed Doses Matter

Mounjaro (tirzepatide) and Wegovy (semaglutide) are both long-acting medicines designed to be taken once a week. They stay in your body for several days after each injection, which is why a weekly schedule works and why a dose taken a little late usually still does its job.

However, the levels of medicine in your body gradually fall between doses. If too much time passes, your body starts to lose some of its tolerance to the medicine. This matters because both treatments are started at a low dose and increased slowly, specifically to help your digestive system adjust. Jumping straight back to a high dose after a long break can bring back side effects such as nausea, vomiting and diarrhoea, sometimes more strongly than when you first started.

Missed doses can also affect your results. You may notice your appetite returning, cravings creeping back or your weight loss slowing down. This is normal and usually settles once you are back on a regular routine, but it is a good reason to get back on track promptly and safely.

• Both medicines work best when taken on the same day each week
• A single late dose is usually manageable if you follow the licensed window
• Longer gaps can reduce your tolerance and increase side effects on restarting
• Appetite and cravings may return temporarily after a missed dose

Missed Dose Rules at a Glance

These rules come from the official UK product information for each medicine, which you can read in full on the electronic medicines compendium: Mounjaro KwikPen, Wegovy FlexTouch and Wegovy tablets.

Missed a Mounjaro Dose? What to Do

If It Has Been 4 Days or Less

If you realise you have missed your Mounjaro injection and no more than 4 days have passed since your usual injection day, take the missed dose as soon as you remember. Then take your next dose on your normal day as usual.

For example, if you normally inject on a Monday and remember on Thursday, you can inject on Thursday and then carry on with your next injection the following Monday. Friday would be the last day you could still take a Monday dose. Be cautious of the time of day, however, as you should inject within 96 hours of the scheduled dose.

If It Has Been More Than 4 Days

If more than 4 days have passed, do not take the missed dose. Skip it completely and take your next dose on your usual day. Using the same example, if you inject on Mondays and only remember on Saturday, wait until Monday and take your normal dose then.

• Never take two doses to make up for the one you missed
• Do not try to dial or draw extra medicine from your KwikPen
• Stay on your current dose strength unless your prescriber tells you otherwise
• Let your pharmacist know if missed doses are becoming a pattern

Mounjaro is supplied in the UK as a multi-dose KwikPen, so a missed week may also leave you with a dose remaining in your pen at the end of the month. That is fine. Simply use it the following week, and let us know so we can adjust the timing of your next supply. It is important to note that the pen must be discarded 30 days after first use, even if medicine remains, so if you are exceeding this 30 day limit, discard the pen. If you are unsure how to use the pen correctly, our guide on how to inject Mounjaro covers the technique step by step.

Missed a Wegovy Injection? What to Do

If It Has Been 5 Days or Less

Wegovy has a slightly longer catch-up window than Mounjaro. If you have missed your weekly injection and no more than 5 days have passed, take the missed dose as soon as you remember, then continue with your next dose on your usual day.

For example, if you normally inject on a Monday and remember on Friday, inject on Friday and take your next dose the following Monday as normal.

If It Has Been More Than 5 Days

If more than 5 days have passed, skip the missed dose and wait until your next scheduled injection day. Do not double up. The UK product information for Wegovy also states that if more doses are missed, reducing the starting dose should be considered when treatment is restarted. We cover this in more detail below.

• Take the missed dose within 5 days, or skip it if the window has passed
• Return to your normal weekly injection day afterwards
• Never take two doses in one week to catch up
• If you have missed more than one dose, speak to a pharmacist before injecting

Missed a Wegovy Tablet? What to Do

The oral version of semaglutide works differently when it comes to missed doses. Because it is taken every day rather than once a week, there is no catch-up window. If you forget to take your tablet in the morning, skip it and take your next tablet the following day as normal.

You should never take two tablets on the same day to make up for one you missed. It is also important to keep following the usual instructions for taking the tablet: on an empty stomach, with a small amount of water, and waiting at least 30 minutes before eating, drinking or taking other oral medicines. If you have missed several days in a row, speak to your pharmacist before carrying on, as you may need to restart at a lower strength. You can read more about the oral version in our Wegovy pill guide.

• Skip the missed tablet, do not take it later in the day
• Take the next tablet the following morning as normal
• Never take two tablets in one day
• Several days missed? Check with your pharmacist before continuing

What If You Have Missed More Than One Dose?

Missing a single dose and following the licensed window is usually straightforward. Missing two or more doses in a row is different, and this is where professional advice becomes important.

The UK product information does not set one fixed rule for exactly how many missed weeks means you must restart from a lower dose. Instead, your prescriber will make a decision based on your individual situation. The aim is to get you back on treatment at a dose that is effective but that your body can tolerate comfortably.

Why Restarting at a Lower Dose May Be Needed

After a longer break, your digestive system may no longer be used to the medicine. Restarting directly at a high dose, such as 10mg or 15mg of Mounjaro or 2.4mg of Wegovy, can cause significant nausea, vomiting and diarrhoea. Severe or prolonged vomiting and diarrhoea can lead to dehydration, which in some people can affect kidney function. Restarting at a lower dose and building back up gradually helps reduce this risk.

What Your Pharmacist Will Consider

When you get in touch, your pharmacist or prescriber will usually want to know:

• Which medicine you use and your current dose strength
• The date of your last injection or tablet
• How many doses you have missed in total
• How well you tolerated your current dose before the break
• Whether you have been unwell, for example with vomiting or diarrhoea
• Any new medicines or changes to your health since your last review

Based on this, they may advise you to continue at your current dose, step down to a previous dose for a few weeks, or in some cases restart from the lowest starting dose and build back up. Restarting at a lower dose does not mean you are starting from scratch with your weight loss. Many people find they can return to their previous dose relatively quickly once their body has readjusted, but the pace will always depend on how you feel.

What to Expect When You Restart

Even at a lower dose, it is common to feel some mild digestive side effects in the first few days after restarting. Eating smaller meals, avoiding rich or fatty foods, and drinking plenty of fluids can help. If you notice that side effects are stronger than you expected, contact us before your next dose. Our article on Mounjaro side effects covers how to manage the most common symptoms.

Mounjaro, Missed Doses and Contraception

If you take an oral contraceptive pill and use Mounjaro, there is an extra point to be aware of. Mounjaro’s product information advises that it may reduce how well oral contraceptives work in people who are overweight. People in this situation are advised to switch to a non-oral method of contraception, or add a barrier method such as condoms, for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.

This matters if you have missed doses, because restarting at a lower dose and then stepping back up means you will go through dose increases again. Each of those increases may mean another 4-week period where extra contraception is recommended. This advice applies to Mounjaro rather than Wegovy. You can read more in our guide to Mounjaro and contraception.

Neither Mounjaro nor Wegovy should be used during pregnancy, while trying to conceive or while breastfeeding. If you think you might be pregnant, stop treatment and speak to a healthcare professional.

Things You Should Never Do After a Missed Dose

It is natural to want to “catch up” after missing a dose, but some well-meant actions can do more harm than good. To stay safe:

• Do not take a double dose, either on the same day or within a few days of each other
• Do not try to draw or dial extra medicine from your pen
• Do not move up to the next dose strength to make up for lost time
• Do not restart at a high dose after a long break without speaking to a pharmacist
• Do not borrow or share pens or tablets with anyone else
• Do not buy medicine from unregulated online sellers or social media if your supply has run out

Changing Your Injection Day

Sometimes a missed dose is a sign that your current injection day simply does not suit your routine. Both Mounjaro and Wegovy allow you to change your weekly injection day if needed, as long as there are at least 3 days between two doses. For example, if you usually inject on a Monday but your weekends are calmer, you could take your next dose on Thursday and then continue on Thursdays from then on. If you would like to make a permanent change, let your pharmacist know so we can help you plan it and keep your prescription supply on schedule.

If You Have Accidentally Taken Too Much

If you think you have injected twice in a week or taken more than your prescribed dose, contact your pharmacist or NHS 111 for advice. Taking too much can cause severe nausea, vomiting and diarrhoea, and because these medicines are long-acting, the effects can last for several days. Bring the pen or packaging with you if you need to be seen.

When to Seek Urgent Medical Advice

Most problems around missed doses are about timing and tolerance rather than emergencies. However, you should seek urgent medical help if, at any point during treatment, you experience:

• Severe, persistent abdominal pain, which may spread to your back, with or without vomiting, as this can be a sign of pancreatitis
• Vomiting or diarrhoea that stops you keeping fluids down
• Signs of dehydration, such as dizziness, very dark urine or passing very little urine
• Symptoms of low blood sugar, such as shaking, sweating or confusion, particularly if you also take insulin or a sulfonylurea for diabetes
• Signs of a serious allergic reaction, such as swelling of the face or throat or difficulty breathing

If you are unwell with a stomach bug or another illness around your injection day, speak to a pharmacist before taking your dose. In some cases it may be sensible to wait until you are feeling better.

Practical Tips to Avoid Missing a Dose

The easiest missed dose to deal with is the one that never happens. A few simple habits can help you stay on track:

• Set a weekly phone reminder for your injection day and time
• Choose an injection day that fits your routine, such as a quieter weekend morning
• Keep a simple log or calendar to tick off each dose
• Order your next supply early, so you never run out before your injection day
• Plan ahead for holidays and travel, and take your medicine with you if needed
• For Wegovy tablets, keep your pack next to something you see every morning

If you are thinking about changing treatment because the routine does not suit you, our guide on switching from Mounjaro to Wegovy explains what that process involves.

Frequently Asked Questions

Getting Back on Track With Confidence

Missing a dose of Mounjaro or Wegovy happens to many people, and in most cases it is easy to manage. The key is knowing your medicine’s window: 4 days for Mounjaro, 5 days for Wegovy injections, and no catch-up for Wegovy tablets. If you have missed more than one dose, the safest step is to speak to a pharmacist before restarting, so your dose can be adjusted to keep side effects to a minimum.

• Follow the licensed missed-dose window for your medicine
• Never double up or increase your dose to catch up
• Seek advice before restarting after multiple missed doses
• Remember the extra contraception advice if you use Mounjaro and the pill

Our team at REX Pharmacy is here to help you stay on track with your treatment and answer any questions about missed doses, restarting or adjusting your routine.

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You can also get in touch with us if you need advice about a missed dose before your next injection.