Carbimazole

Anti-thyroid medicine
PRESCRIPTION ONLY IN INDIA

Carbimazole is a anti-thyroid medicine found in 1 medicine sold in India, such as Neo-Mercazole 5. Below: what it is for, how it works, how to take it, side effects, interactions and pregnancy advice.

What it is used for

Reduces thyroid hormone in an overactive thyroid.

How it works

An anti-thyroid medicine that reduces thyroid hormone production in an overactive thyroid (Graves' disease).

How to take it

Usually a higher starting dose, reduced over weeks; courses often last 12 to 18 months with regular blood tests.

Common side effects

  • Rash
  • Itching
  • Nausea
  • Headache
  • Joint pain

Get medical help straight away if

  • Sore throat, mouth ulcers or fever (possible dangerous drop in white cells
  • Get a blood test straight away)
  • Yellow skin

Be careful

Report sore throat or fever at once (rare effect on white blood cells).

Other medicines and interactions

Can change warfarin effect.

Pregnancy and breastfeeding

Avoided in the first three months of pregnancy (propylthiouracil is used instead); low doses acceptable while breastfeeding.

Brands of Carbimazole (1)

Neo-Mercazole 5

Common questions

What is Carbimazole used for?

Reduces thyroid hormone in an overactive thyroid.

How does Carbimazole work?

An anti-thyroid medicine that reduces thyroid hormone production in an overactive thyroid (Graves' disease).

How should I take Carbimazole?

Usually a higher starting dose, reduced over weeks; courses often last 12 to 18 months with regular blood tests.

What are the side effects of Carbimazole?

Common: Rash, itching, nausea, headache, joint pain. Get help straight away for: Sore throat, mouth ulcers or fever (possible dangerous drop in white cells, get a blood test straight away), yellow skin.

Does Carbimazole interact with other medicines?

Can change warfarin effect.

Is Carbimazole safe in pregnancy and breastfeeding?

Avoided in the first three months of pregnancy (propylthiouracil is used instead); low doses acceptable while breastfeeding.

Does Carbimazole need a prescription in India?

Yes. In India it is a prescription (Schedule H) medicine, so a pharmacist should sell it only with a doctor's prescription.

Which brands contain Carbimazole?

Neo-Mercazole 5.

Sources and further reading

NHS (UK National Health Service) and MedlinePlus (US National Library of Medicine) are free, reviewed medicine guides. Brand names and doses there may differ from India.

Last reviewed 31 October 2026. Written by Satya Babu from standard prescribing information.

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For information only, not medical advice. This page is a plain-language summary written from standard prescribing information and the public guides linked below. Brands sometimes change their formula, so always check the composition printed on the pack. Doses here are typical adult doses; yours may differ. Do not start, stop or change a medicine without your doctor or pharmacist, and keep all medicines away from children. In an emergency, call 112 (India) or your local emergency number.