What to do if your GLP-1 pen looks wrong

Before you inject — the immediate action ladder

1. Stop. Don’t inject. The next scheduled dose can wait until you’ve worked out what you have.
2. Don’t damage the pen or the packaging. Keep everything — the carton, the PIL (or its absence), the pen itself, any shipping label.
3. Photograph everything. All sides of the carton, the PIL, the pen body, the cartridge if visible. Good lighting, in focus, multiple angles.
4. Contact the supplier in writing. If it was a GPhC-registered UK pharmacy, they need to know and can initiate their own incident process. If it was an unlicensed online seller, your written contact is potential evidence.
5. Report to MHRA via Yellow Card. yellowcard.mhra.gov.uk covers both adverse events and fake medicines.
6. Report via the GOV.UK supply form. Report a problem with a medicine or medical device. Include the URL, payment evidence, and shipping route.
7. If purchased via unlicensed supply, report to Action Fraud. actionfraud.police.uk.
8. Talk to your prescriber. They need to know, and you may need an interim supply through a verified UK channel.

If you've already injected

1. Don’t inject again.
2. Contact your prescriber. Or NHS 111 if your prescriber isn’t reachable.
3. Watch for these:
   • Unusual injection-site reactions, abscess, persistent redness/pain — possible infection from non-sterile product.
   • Severe nausea or vomiting out of proportion to your usual response.
   • Severe abdominal pain (possible pancreatitis).
   • Hypoglycaemia (sweating, shaking, confusion) — especially relevant if the counterfeit pen may have contained insulin instead of semaglutide / tirzepatide. Eat fast-acting carbohydrate immediately and seek urgent care.
   • Allergic reaction symptoms — swelling, hives, difficulty breathing — emergency.
4. Complete the Yellow Card report — it now includes the adverse event as well as the suspect-product element.

What to include in the report

• Product name and strength as printed on the pen.
• Batch number and expiry from box and pen.
• Photos of everything.
• Source (URL of seller, name of pharmacy, name of intermediary).
• Payment route and payment date.
• Shipping route and arrival date.
• Whether you injected and any symptoms.
• Your contact details (or a way to anonymously contact you if you prefer).

Why this matters

Individual reports feed the pattern that triggers MHRA investigations and public alerts. The February 2026 falsified Mounjaro 15 mg KwikPen alert was built on patient and pharmacy reports. The next alert depends on the next report — yours could be it.