Carbimazole Propylthiouracil (PTU) Warning

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To the patient: warning- please read this now

Carbimazole/PTU treatment and sore mouth/throat

You have been started on carbimazole treatment for an overactive thyroid. This is a very safe treatment that has been used for over 50 years.

However, very rarely, a patient reacts to the drug with a sudden loss of white blood cells (‘neutrophils’) from the blood.

If you suspect this may have happened:

•  Do not take any more doses of the tablet
• Contact an emergency doctor or a casualty department the same day (even if it is a weekend) and show them this letter and or the tablets

To the doctor:

This patient is on Carbimazole or PTU. If he/she has a sore throat or mouth it may indicate agranulocytosis, a very rare side effect.

Please:

• Stop carbimazole/PTU immediately
• Check neutrophil count urgently, NOT just the total white cell count (which may be normal). If the neutrophil count is < 1.0 do NOT recommence treatment and admit patient for neutropaenia. If the neutrophil count is 1.0 – 2.0, measure it again the next day off treatment. If it is >2.0, it is safe to continue treatment
• Carbimazole/PTU and thyrotoxicosis also cause a mild reduction in white cell count which is of no significance. A skin rash on carbimazole/PTU is also common and does not indicate neutropaenia

Useful contact details

There is more information about thyroid treatment on our website.

This information is intended for patients receiving care in Brighton & Hove or Haywards Heath.

The information in this leaflet is for guidance purposes only and is in no way intended to replace professional clinical advice by a qualified practitioner.