The Yellow Card Scheme: Reporting a Mounjaro Side Effect

The Yellow Card scheme is the MHRA's system for reporting suspected side effects of medicines, and both the SmPC and NHS point to it for tirzepatide. Mounjaro is a newer medicine under additional monitoring (the black triangle), so reports are especially valuable. You can report any suspected side effect yourself at the Yellow Card website or app. Reporting does not replace getting medical help; for serious side effects, contact 111 or seek urgent care.

If you have had a side effect on Mounjaro, you can help make the medicine safer for everyone by reporting it through the MHRA's Yellow Card scheme. It takes a few minutes, you can do it yourself, and for a relatively new medicine like this, your report genuinely adds to the safety picture.

This guide explains what the Yellow Card scheme is, why reporting matters for a medicine under additional monitoring, what you can report, how to do it, and how reporting fits alongside getting medical help. It draws on the UK Summary of Product Characteristics and the NHS. Reporting is important, but it does not replace seeking medical advice for a side effect that needs attention.

What is the Yellow Card scheme?

The Yellow Card scheme is run by the MHRA (the UK medicines regulator) to collect reports of suspected side effects and safety issues with medicines ¹. Both the Mounjaro SmPC and the NHS direct people to it for reporting suspected adverse reactions to tirzepatide ¹².

The scheme exists because clinical trials, however large, cannot detect every possible side effect, especially rarer ones or those that only emerge with wider, longer use ¹. Real-world reports fill that gap and help the regulator monitor the balance of benefits and risks ¹.

So the Yellow Card scheme is a core part of how medicine safety is tracked after a product is in use, and patients, carers and healthcare professionals can all contribute ¹².

A useful way to think about it is that licensing a medicine is the beginning of monitoring its safety, not the end ¹. Trials are conducted in selected groups over defined periods, whereas once a medicine is widely used it is taken by far more people, with varied health and other medicines, for longer ¹. The Yellow Card scheme is how that much larger, real-world experience is captured, and it is the same system used for every medicine in the UK, not something specific to weight-loss treatments ¹².

Why reporting matters for Mounjaro

Mounjaro is a relatively new medicine and is subject to additional monitoring, marked by a black triangle symbol in its information, which means the regulator is actively gathering safety data and healthcare professionals are specifically asked to report suspected reactions ¹. So reporting is especially valuable here ¹.

Because weight-loss use of tirzepatide is widespread and still accumulating long-term real-world experience, each report adds to the evolving picture, including for effects that may be uncommon or not yet well characterised ¹. Your report can contribute to that ¹.

This is not a reason for alarm about the medicine; additional monitoring is a normal status for newer treatments, and the point is simply that reporting is encouraged and useful ¹. The black triangle does not mean a medicine is unsafe or under suspicion; it simply flags that it is relatively new and that the regulator is keen to gather data, which is a sensible, routine part of how newer medicines are monitored ¹. Seeing it should reassure rather than worry you, because it means the safety of the medicine is being actively watched ¹.

What you can report

You can report any side effect you suspect may be linked to Mounjaro, whether or not you are certain it was caused by the medicine ¹². You do not need to prove the link; a suspicion is enough, and the regulator assesses the patterns across many reports ¹.

This includes common effects like nausea, less common ones, and anything that worries you or does not go away ². The NHS notes the listed side effects are not exhaustive and points to Yellow Card for reporting any you experience ².

So there is no threshold you have to meet to report; if you suspect a side effect, it is worth reporting, which helps build the fuller safety picture ¹².

People sometimes hold back from reporting because they are not sure the medicine was responsible, or because the effect seems minor, but neither is a reason not to report ¹. The whole point of the scheme is that the regulator, not the individual, works out the patterns: a single uncertain report means little on its own, but many similar reports can reveal a signal that no one person could see ¹. So reporting a suspicion you are unsure about is genuinely useful, and you do not need to second-guess whether it counts ¹².

Considering treatment for weight management? You can start an assessment with a Cloud Pharmacy clinician, who will review your medical history and confirm whether treatment is appropriate.

How to report

Reporting is designed to be straightforward. You can submit a report yourself through the Yellow Card website (yellowcard.mhra.gov.uk) or the Yellow Card app, which you can find by searching for 'MHRA Yellow Card' in the Google Play or Apple App stores ¹. The NHS likewise points to the Yellow Card website for reporting side effects ².

When reporting, it helps to have details to hand such as the medicine name (tirzepatide / Mounjaro), the side effect you experienced, when it started, and any other medicines you take, though you can report with the information you have ¹². Healthcare professionals can also report on your behalf ¹.

If you are unsure how to report or want help, a pharmacist or your prescriber can guide you, and they can submit a report too ². The important thing is that the report is made ¹.

You do not need to be precise or medically expert to file a report ¹. Describing what happened in your own words, when it started in relation to taking the medicine, and how it affected you, is enough; the regulator does not expect you to use clinical terms or to be certain of the cause ¹. If you cannot remember every detail, report what you can, since a partial report still adds to the picture and is far better than not reporting at all ¹².

What happens to your report

Reports are collected and reviewed by the MHRA, which looks for patterns across many reports to monitor the safety of the medicine and identify any new safety signals ¹. A single report contributes to that wider analysis ¹.

If the regulator identifies a concern, it can take action, such as updating the product information, issuing safety advice, or other regulatory steps ¹. This is how the real-world safety of medicines is kept under review after they are licensed ¹.

So your report is not just logged and forgotten; it feeds into ongoing safety monitoring that benefits everyone using the medicine ¹. That is the value of taking a few minutes to submit it ¹.

For a medicine under additional monitoring like Mounjaro, this feedback loop is particularly active, because the regulator is specifically looking to build the safety picture for a relatively new and widely used treatment ¹. That is also why the product information carries the black triangle and why healthcare professionals are asked directly to report ¹. Patient reports complement those professional ones, capturing experiences that might not otherwise reach the regulator ¹². Both kinds of report feed the same system, and yours counts alongside a clinician's rather than being a lesser version of it ¹.

Reporting and getting medical help

It is important to understand that reporting a side effect is not the same as getting medical help for it². The Yellow Card scheme is for safety monitoring; if a side effect needs attention, you still need to seek care ².

So for side effects that bother you or do not go away, the NHS advises speaking to a pharmacist or doctor, and for anything you think might be a serious side effect, calling 111 or seeking urgent help ². Severe, persistent abdominal pain, for example, is a red flag that needs immediate attention regardless of any report ².

So do both where relevant: get the care you need first, and report the side effect through Yellow Card to help the wider safety picture ¹². Our guide on Mounjaro side effects covers what is normal and what needs attention ².

Thinking of them as two separate jobs avoids a common mistake ². Some people delay getting help because they assume reporting through Yellow Card has somehow alerted a clinician, but it has not: the scheme is for regulatory monitoring, and it does not summon medical care ². So if a side effect is worrying you, contact a pharmacist, your prescriber or 111 for the care, and treat the Yellow Card report as the separate, valuable contribution to safety that it is ¹².

Frequently asked questions

What is the Yellow Card scheme?

It is the MHRA's system for reporting suspected side effects and safety issues with medicines, and both the Mounjaro SmPC and the NHS direct people to it for tirzepatide ¹². Real-world reports help the regulator monitor a medicine's benefits and risks beyond what clinical trials can detect ¹.

Why should I report a Mounjaro side effect?

Mounjaro is a newer medicine under additional monitoring (the black triangle), so the regulator actively wants suspected-reaction reports, and weight-loss use is still building long-term real-world experience ¹. Each report adds to the safety picture, including for uncommon or not-yet-characterised effects ¹.

What can I report on a Yellow Card?

Any side effect you suspect may be linked to Mounjaro, whether or not you are certain it was caused by the medicine ¹². You do not need to prove the link, and the NHS notes the listed side effects are not exhaustive, pointing to Yellow Card for any you experience ².

How do I report a Mounjaro side effect?

Submit a report yourself at the Yellow Card website (yellowcard.mhra.gov.uk) or the Yellow Card app (search 'MHRA Yellow Card' in the app stores), and the NHS also points there ¹². Have details like the medicine name, the side effect, when it started and your other medicines to hand; a pharmacist or prescriber can also report for you ¹².

What happens after I submit a Yellow Card report?

The MHRA collects and reviews reports, looking for patterns across many to monitor safety and identify new signals ¹. If a concern is found, it can act, for example by updating the product information or issuing safety advice ¹. Your report feeds into ongoing safety monitoring ¹.

Does reporting a side effect replace seeing a doctor?

No. Reporting through Yellow Card is for safety monitoring, not treatment ². For side effects that bother you or do not go away, speak to a pharmacist or doctor, and for suspected serious side effects call 111 or seek urgent help ². Get the care you need first, then report to help the wider picture ¹².

Your next step

The Yellow Card scheme is the MHRA's system for reporting suspected side effects, and both the SmPC and NHS point to it for tirzepatide. Mounjaro is a newer medicine under additional monitoring, so reports are especially valuable, and you can report any suspected side effect yourself at the Yellow Card website or app, whether or not you are certain of the link.

If you have a side effect, get the care you need first, speaking to a pharmacist or doctor, or calling 111 for anything you think might be serious, and then report it through Yellow Card to help keep the medicine's safety picture current. A pharmacist or prescriber can also submit a report for you, and you do not need to be certain of the cause or use medical terms; describing what happened in your own words, with what you can remember, is enough, and even an uncertain report adds to the wider safety picture for a medicine still building its long-term real-world record, so it is always worth taking the few minutes to do.

Disclaimer

This guide is for general information only and does not constitute medical advice, diagnosis or treatment. The information here describes general clinical context based on UK regulatory sources cited above; it is not a recommendation for any specific medicine or treatment, which can only be made by a prescriber following individual assessment.

If you are considering treatment, speak to your GP or pharmacist, or arrange a consultation with a Cloud Pharmacy clinician. Prescription-only medicines are issued only after clinical assessment and where appropriate.

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

References

1. 4.8 Undesirable effects (additional monitoring / black triangle; report suspected adverse reactions via the MHRA Yellow Card scheme)
2. Tirzepatide (report side effects on the Yellow Card website; listed side effects not exhaustive; speak to a pharmacist or doctor; call 111 for serious side effects)