Always follow the advice of a doctor, and the instructions that come with your medicine.
Dosage and how to take carbimazole
Dosage and strength
Carbimazole comes as 5mg, 10mg, 15mg and 20mg tablets. You may need to take more than 1 tablet to make up your dose.
Doses vary depending on your symptoms, your thyroid hormone levels and whether you have any other health conditions. Your doctor will tell you how many tablets to take.
The usual starting dose for adults is between 20mg and 60mg a day.
When you first start taking carbimazole, you will take it 2 or 3 times a day. Try to space the doses evenly throughout the day. If you take it 3 times a day, you could take it first thing in the morning, in the middle of the afternoon and at bedtime.
The starting dose for children depends on their age and weight. Children may take it once a day, or divided into 2 or 3 smaller doses.
How to take it
Swallow the tablets whole, with a drink of water.
You can take carbimazole with or without food.
Having blood tests during treatment
You need to have blood tests before you start taking carbimazole and during treatment. These tests are important to check the levels of thyroid hormones in your body.
Depending on the results, your doctor may need to increase or reduce your dose to get these hormones to the right levels. When your levels are stable, you can usually go onto a lower dose, taken once a day.
When you first start treatment, you'll have blood tests every 6 weeks or so. Once your hormone levels are stable, you'll have a blood test every 3 months, for as long as you continue to take carbimazole.
However, you may need blood tests more often if you:
- are pregnant
- have symptoms or side effects that could mean your dose is not quite right
How long to take it for
Once your thyroid hormone levels are under control, your dose of carbimazole may be gradually lowered and then stopped. Depending on your condition, you may need to take carbimazole for 12 to 18 months.
Some people need to continue taking the medicine for several years, possibly for the rest of their life.
However, if carbimazole is not working for you, your doctor may suggest alternatives such as radioactive iodine treatment or surgery to remove part or all of your thyroid.
If you forget to take it
If you forget to take a dose, take it as soon as you remember. If it's time for your next dose, take both doses together.
If you forget doses often, it may help to set an alarm to remind you. You can also ask your pharmacist for advice on other ways to help you remember to take your medicine.
If you take too much
If you take 1 extra dose of carbimazole, it's unlikely you will get more side effects.
Urgent advice: Contact 111 for advice now if:
- you have taken 2 or more extra doses of carbimazole
Call 111 or get help from 111 online.
If you need to go to A&E, do not drive. Ask someone to drive you or call 999 and ask for an ambulance.
Bring the carbimazole packet or leaflet inside it, any remaining medicine, and any other medicines you take.
Stopping carbimazole
Do not stop taking carbimazole without speaking to your doctor first.
If you stop taking your medicine, your thyroid hormone levels will rise and you will start to feel ill again. This may not happen straight away. It can take time for your thyroid hormone levels to become too high and for your symptoms to come back.