• Keep your regular appointments with your doctor so that your condition can be monitored and any dose adjustments made.
  • Important: if you develop an infection, a sore throat, mouth ulcers, a high temperature, unusual bruising, or if you generally feel unwell while you are taking carbimazole, contact your doctor immediately.

About carbimazole

Type of medicine Antithyroid
Used for Hyperthyroidism
Also called Neo-Mercazole®
Available as Tablets

An overactive thyroid gland produces too much thyroid hormone which causes a condition known as hyperthyroidism. This can lead to symptoms such as changes in weight, sweating, irritability, shaking, diarrhoea, tiredness, intolerance of hot temperatures, worry and menstrual problems.

Carbimazole works by reducing the amount of thyroid hormones made by your thyroid gland.

Carbimazole may be used alone or together with other treatments for hyperthyroidism. It is also used in preparation for thyroidectomy (part or total removal of the thyroid gland) and before radioiodine treatment.

Before taking carbimazole

Before taking carbimazole make sure your doctor or pharmacist knows:

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have been told by a doctor that you have problems with your blood cell counts.
  • If you have liver problems.
  • If you are taking other medicines, including those available to buy without a prescription, herbal or complementary medicines.
  • If you have ever had an allergic reaction to this or to any other medicine.

How to take carbimazole

  • Before starting carbimazole, read the manufacturer's printed information leaflet.
  • Take carbimazole tablets exactly as your doctor has told you to. Make sure you know how many tablets to take each day.
  • Try to take your dose at the same time(s) each day to avoid missing any doses. Swallow the tablets with a drink of water.
  • You can take carbimazole tablets before, during or after meals.
  • If you miss a dose, take it as soon as you remember. If your next dose is due, you may take both doses together. If you have missed more than one dose, or if you are having problems remembering to take your tablets at the correct time, speak with your doctor or pharmacist for further advice.
  • In order to maintain control of the thyroid gland, you may need to take carbimazole tablets for several months, although your doctor may reduce your dose after a month or so. Your doctor will decide when treatment can be stopped.
  • You may need to have blood tests from time to time to check how you are responding to treatment.

Getting the most from your treatment

  • You must keep your regular appointments with your doctor so that your condition can be monitored and any dose adjustments to carbimazole can be made.
  • Do not change the dose of carbimazole you are taking without consulting your doctor first.
  • Before having any kind of medical treatment, including dental or emergency treatment, tell the person carrying out the treatment that you are taking carbimazole.

Can carbimazole cause problems?

Along with their useful effects, all medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Side-effects What can I do if I experience this
Feeling sick, stomach upset Eat little and often. Stick to simple foods
Headache Ask your pharmacist to recommend a suitable painkiller. If the headache continues, speak with your doctor
Skin rash, itching Let your doctor know about this, as treatment with an antihistamine may be recommended for you
Other possible side-effects: changes to your taste, fever, tiredness, painful joints If any of these become troublesome, let your doctor know

Important: if you develop either of the following contact your doctor straight away:

  • An infection, sore throat, mouth ulcers, high temperature, unusual bruising or bleeding, or if you generally feel unwell.
  • Jaundice (yellowing of the skin and whites of the eyes).

If you experience any other symptoms, which you think may be due to this medicine, discuss them with your doctor or pharmacist.

How to store carbimazole

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.