Carbimazole in Pregnancy and Breastfeeding

Risk Factor: D
Class: Hormones / Antithyroid agents

Contents of this page:
Fetal Risk Summary
Breast Feeding Summary
Questions and Answers

Fetal Risk Summary

Carbimazole is converted in vivo to methimazole (1). See Methimazole.

Breast Feeding Summary

See Methimazole.


  1. Haynes RC Jr, Murad F. Thyroid and antithyroid drugs. In Gilman AG, Goodman LS, Gilman A, eds. The Pharmacological Basis of Therapeutics. 5th ed. New York, NY:MacMillan Publishing Co, 1980:1411.

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Questions and Answers

carbimazole?, for grave's disease - i got a sore throat when on the meds and got told to get a blood test (as one of the bad side effects are sore throats) anyway my results came back and said theres a virus thing that they found in my blood and thats all they said, now i don't know if i should take it or not? i can't get a new doctor as everywhere near me is full i don't know what to do

well like you i was on carbimazole. i was on it for 9 months and my graves disease got worse. although i never suffered with a sore throat?
i was question that with your gp
i then had my thyroid partially removed 10 years ago and im now on thyroxine.

I am on 40mg of carbimazole and have only one mouth ulcer, is it worth mentioning to my doctor?, I do not have a sore throat but mouth ulcer on tip of my tongue is big. I have read that you should tell your doctor about mouth ulcers.

Yes, you should tell your doctor about mouth ulcers.
You will probably need to go in for a white cell count just to be on the safe side.

Will I put a lot of weight on taking 40mg carbimazole every day?, I lost 2 stone before I was diagnosed with Graves Disease and I'm terrified of putting it all back on.

no , but try to aquire a more healthy style

Can you get Anxiety from Carbimazole?, I have been diagnosed with an over active thyroid and after starting My carbimazole tablets i have started getting hot and cold flushes (only today) but have regularly been tapping and generally on edge i never had any of this before and wondered if its the tablets causing this problem.


I have had an overactive thyroid and have been on carbimazole and atenolol. Has anyone had radioactive iodine?, I have an appointment to have radioactive iodine for this but I am unsure whether to go ahead with it or not. Anyone know the pros and cons? Anyone know anyone who has had this treatment?

Yep had to have the capsule on three different occasions before it worked.Have now to take iodine pills fifteen Min's before eating in the morning.I have no trouble at all now,my weight is back to normal no feelings of tiredness or any
of the bad symptoms i have.So go ahead with your
treatment,no side affects with capsules.Good luck.
I am an older guy.
PS sometimes one treatment dose it but my thyroid that big took 3 goes

I was diagnosed with hyperthyroidism.Im treating it with carbimazole.What can i do about the buldging eyes?,

Sometimes an uncommon problem called Grave's ophthalmopathy may affect your eyes.In this disorder your eyeballs protrude beyond their normal protective orbits when tissues and muscles behind your eyes swell.This pushes your eyeballs forward so far that they actually bulge out of your orbits.This can cause the front surface of your eyeballs to become very dry.People with Grave's ophthalmopathy develop eye problems,including bulging,red or swollen eyes,sensitivity to light, and blurring or double vision. You can manage mild signs and symptoms by avoiding wind and bright lights and using artificial tears and lubricating gels.If your symptoms are more severe, your doctor may recommend treatment with corticosteroids, such as prednisone, to reduce swelling behind your eyeballs.In some cases, a surgical procedure may be an option:
-orbital decompression surgery
-eye muscle surgery

Once you begin treatment ,symptoms of hyperthyroidism should subside and you should start feeling much better.The following suggestions also may help:
-ask your doctor about supplementing your diet
-maintain an adequaute intake of calcium
If you have Grave's ophthalmopathy,the following suggestions may help soothe your eyes or skin:
-apply cool compresses to your eyes
-wear sunglasses
-use lubricating eyedrops
-elevate the head of your bed
-try over-the-counter creams for swollen skin

does anyone know the maximum length of time a patient should take carbimazole for an overactive thyroid?, my boyfriend takes 20mg of carbimazole for an overactive thyroid and has been taking it for nearly four years now and im worried that he has been on it for to long as there are many risks in taking the drug. has anyone been on the drug for this long ? or no of the average amount of time a patient is to take the drug? im worried the doctor is not doing enough as ive heard of other patients being given radioactive iodine treatment, and changing medications. if anyone has advice or knows anything about this please let me no. Thanks

4 years is too long. The medical treatment, using antithyroid drugs like carbimazole is 18 months to 2 years and is only 40% affective. It is often used to stabilise the thyroid prior to administering radio active iodine or surgical thyroidectomy...this would render the patient hypothyroid but tends to resolve the problem and the patient would remain on thyroxine for life. Your boyfriend should have attended a endocrinologist and a plan of care should have been made...if not he needs to ask for this.
Good luck. x

after who long from stopping of carbimazole thyroid function test is requested?,

30 days

Which medicines should I take? PTU, carbimazole and thiamazole?, I am being treated for a Hyperthyrodism and am on Thimazol 5mg S.C. tab*(Methimazole) for years.

I have developed some additional side effort.

1995 took PTU
1996~1998 took Carbimazole
2001 I 131
1999~2007 took Thimazol

What should I ask my doctor to treat my Hyperthyrodism?

you better tell your doctor what side effects you are experiencing.. he needs to know your reaction to the drugs before he can prescribe you with anything.. a good medical and in your case drug history will be very helpful in deciding the appropriate drug for your condition..

will carbimazole give a total cure for goiter?,

it suppresses the production of thyroid hormones ,it doesnt cure its reduces uptake of iodine resulting in less thyroid hormone production