Missing a weekly dose of Mounjaro (tirzepatide) is a common concern for people managing type 2 diabetes. Whilst occasional missed doses are unlikely to cause serious harm, understanding the correct approach to resuming treatment is essential for maintaining optimal blood glucose control. The guidance depends on how much time has passed since your scheduled injection. This article explains when it may be acceptable to skip a dose, the potential risks of missing treatment, and how to safely resume your medication schedule in line with UK prescribing information approved by the MHRA.

Understanding Mounjaro and Its Dosing Schedule

Mounjaro (tirzepatide) is a prescription medicine licensed in the UK for the treatment of type 2 diabetes mellitus in adults. It belongs to a class of medications known as dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonists. By mimicking these naturally occurring hormones, Mounjaro helps regulate blood glucose levels by stimulating insulin secretion when blood sugar is elevated, suppressing glucagon release, and slowing gastric emptying.

The medication is administered as a once-weekly subcutaneous injection, typically on the same day each week. This consistent dosing schedule is designed to maintain steady therapeutic levels of tirzepatide in the body, ensuring optimal glycaemic control throughout the week. Treatment begins with a 2.5 mg dose, which is an initiation dose for tolerability and not intended for glycaemic control. The dose is then gradually increased every four weeks according to individual response and tolerability, with maintenance doses ranging from 5 mg to a maximum of 15 mg weekly.

If needed, you can change your weekly injection day, provided there are at least 72 hours (3 days) between doses.

Adherence to the prescribed weekly schedule is important for achieving the best therapeutic outcomes. The pharmacokinetics of tirzepatide—how the drug is absorbed, distributed, and eliminated from the body—have been specifically designed around this seven-day dosing interval. The medication reaches steady-state concentrations after approximately four weeks of consistent weekly dosing, which is why maintaining regularity is emphasised in treatment protocols.

Understanding your dosing schedule and the importance of consistency helps you manage your diabetes effectively. However, life circumstances occasionally interfere with even the most carefully planned medication routines, which raises important questions about what to do when a dose is missed.

What Happens If You Miss a Dose of Mounjaro

Missing a dose of Mounjaro can affect your blood glucose control, though the extent depends on several factors including how long you've been on treatment, your current dose, and how late the missed dose is administered. When you skip a weekly injection, the therapeutic levels of tirzepatide in your bloodstream gradually decline, which may result in reduced glycaemic control over the following days.

According to the prescribing information approved by the Medicines and Healthcare products Regulatory Agency (MHRA), if you miss a dose of Mounjaro, the recommended action depends on timing. If fewer than four days (96 hours) have passed since your scheduled injection day, you should administer the missed dose as soon as you remember. You can then resume your regular weekly schedule from that point forward. For example, if your usual injection day is Monday and you remember on Wednesday, you should take the dose immediately and then continue with your next injection the following Monday.

However, if more than four days have elapsed since your missed dose, you should skip that dose entirely and wait until your next regularly scheduled injection day.

It's important to note that missing a single dose occasionally is unlikely to cause serious harm for most patients, but your blood glucose levels may be less well controlled during this period. You should monitor your blood sugar more frequently if you miss a dose, particularly if you're also taking other diabetes medications. Never take two doses together to make up for a missed injection, as this significantly increases the risk of adverse effects including nausea, vomiting, and hypoglycaemia.

When It May Be Acceptable to Skip a Week

There are limited circumstances where skipping a week of Mounjaro might be considered acceptable, though this should ideally be discussed with your healthcare provider beforehand. Acute illness is one scenario where temporarily pausing treatment may be appropriate. If you're experiencing severe vomiting, diarrhoea, or dehydration from an unrelated illness, continuing Mounjaro—which can cause gastrointestinal side effects—might worsen these symptoms. If you're unable to maintain adequate hydration, contact your diabetes team for advice on managing your medication during illness.

If you're scheduled for surgery or certain medical procedures, discuss your Mounjaro treatment with both your diabetes team and surgical/anaesthetic team well in advance. Current UK guidance generally recommends continuing GLP-1 receptor agonists in most cases, with individualised risk assessment and management. The medication slows gastric emptying, which can be relevant for procedures requiring anaesthesia or bowel preparation.

If you experience symptoms such as severe abdominal pain (which could indicate pancreatitis), you should stop taking Mounjaro immediately and seek urgent medical attention. Do not restart the medication if pancreatitis is confirmed. Similarly, if you develop signs of a severe allergic reaction (such as difficulty breathing, severe rash, or swelling), seek emergency medical help immediately (call 999) and do not take further doses without medical advice.

It's worth noting that there is no official guidance suggesting it's acceptable to routinely skip doses for convenience or non-medical reasons. Some patients may wonder about skipping doses due to cost concerns, travel difficulties, or side effect management, but these situations should be discussed with your prescriber. Your healthcare team can help address barriers to adherence and may be able to suggest solutions such as dose adjustments, additional anti-nausea medication, or alternative treatment approaches that better suit your circumstances. Self-directed treatment interruptions without medical guidance can compromise your diabetes control and overall health outcomes.

Risks and Considerations of Missing Doses

Missing doses of Mounjaro carries several potential risks that patients should understand. The most immediate concern is loss of glycaemic control. When therapeutic drug levels decline, your blood glucose may rise above target ranges, potentially leading to hyperglycaemia symptoms such as increased thirst, frequent urination, fatigue, and blurred vision. For individuals with type 2 diabetes, even short periods of poor glucose control can contribute to long-term complications if this becomes a pattern.

Inconsistent dosing may also affect the tolerability of Mounjaro when you resume treatment. The medication is initiated at a low dose and gradually increased specifically to minimise gastrointestinal side effects such as nausea, vomiting, diarrhoea, and decreased appetite. When you skip doses and then restart, you may experience a recurrence or worsening of these side effects, similar to when you first began treatment. This can create a cycle where side effects lead to missed doses, which then cause worse side effects upon resumption.

From a clinical effectiveness standpoint, irregular adherence may undermine the medication's ability to provide sustained benefits. Research suggests that consistent use of GLP-1 receptor agonists is associated with better HbA1c reduction and weight management outcomes.

There are also considerations regarding medication storage and waste. Mounjaro pens should be stored in a refrigerator (2°C to 8°C) before first use. Once in use, the pen can be kept at room temperature (below 30°C) for up to 21 days. Never freeze the medication, and discard if it has been frozen. If you're frequently missing doses, you may end up discarding unused medication, which represents both financial waste and environmental concerns.

Additionally, if you're taking other diabetes medications—particularly insulin or sulfonylureas—missing Mounjaro doses without adjusting these other treatments could potentially affect your blood glucose control. Those taking insulin or sulfonylureas should seek advice from their diabetes team about possible dose adjustments if Mounjaro is interrupted. Always inform your diabetes care team about missed doses so they can provide appropriate guidance on managing your other medications during this period.

If you experience any side effects from Mounjaro, you can report them via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk.

How to Resume Treatment After a Missed Dose

Resuming Mounjaro after a missed dose requires careful attention to timing and proper technique. As outlined in the MHRA-approved prescribing information, the approach depends on how much time has passed. If fewer than four days have elapsed since your scheduled injection, administer the missed dose as soon as possible, then return to your regular weekly schedule. For instance, if you normally inject on Thursdays but remember on Saturday, take the dose on Saturday and then resume your Thursday schedule the following week.

If more than four days have passed, skip the missed dose entirely and wait for your next regularly scheduled injection day. Do not attempt to "catch up" by taking extra doses or injecting more frequently than once weekly. When you resume on your regular day, continue with the same dose you were taking before the missed injection.

If you've missed multiple consecutive doses or have been off treatment for a prolonged period, consult your prescriber before resuming, as they may recommend restarting at a lower dose to minimise side effects.

When administering your injection after a gap, follow proper injection technique: rotate injection sites between your abdomen, thigh, or upper arm; ensure the medication has reached room temperature; and check that the solution is clear and colourless. Follow the Instructions for Use provided with your Mounjaro pen for detailed guidance on proper administration.

Remember that you can change your weekly injection day if needed, provided there are at least 72 hours (3 days) between doses.

Monitoring is essential after resuming treatment. Check your blood glucose levels more frequently for several days, particularly before meals and at bedtime. Be alert for signs of hypoglycaemia if you're taking other glucose-lowering medications, and watch for gastrointestinal symptoms which may be more pronounced. If you experience severe or persistent side effects, contact your healthcare provider promptly. To prevent future missed doses, consider setting phone reminders, using a medication tracking app, or linking your injection to a regular weekly activity. If you find yourself frequently missing doses, discuss this openly with your diabetes team—they can help identify barriers and develop strategies to improve adherence, which is crucial for achieving the best possible outcomes from your treatment.

Frequently Asked Questions