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Generic Name: carbimazole
Product Name: Neo-Mercazole

Indication: What Neo-Mercazole is used for

This medicine is used to treat hyperthyroidism or overactive thyroid gland (a condition where the thyroid gland produces too much thyroid hormone).

Ask your doctor if you have any questions about why this medicine has been prescribed for you. Your doctor may have prescribed it for another reason.

This medicine is not addictive.

This medicine is available only with a doctor’s prescription.

Action: How Neo-Mercazole works

Neo-Mercazole contains the active ingredient carbimazole.

This medicine belongs to a group of medicines called antihyperthyroidism agents. These medicines work by reducing the production of thyroid hormones.

It is believed to exert its antithyroid effect by ‘blocking’ the organic binding of iodine through inhibition of the iodination of tyrosine. It is also thought to have some action on peroxidase which is required as a catalyst in the synthesis of thyroxine by the thyroid gland. It does not affect the uptake of iodine by the thyroid gland and this is of vital importance in the treatment of thyrotoxicosis with radioactive iodine or with a combination of radioiodine and Neo-Mercazole, and also in preparation of patients for operation.

Neo-Mercazole contains 5 mg of carbimazole as the active ingredient.
It also contains lactose monohydrate, maize starch, sucrose, magnesium stearate, purified talc, acacia, iron oxide red, gelatin.

This medicine does not contain gluten.

Dose advice: How to use Neo-Mercazole

Before you take NeoMercazole

When you must not take it

Do not take Neo-Mercazole if you have an allergy to:

  • Any medicine containing carbimazole;
  • Any of the ingredients listed here.

Some of the symptoms of an allergic reaction may include:

  • Shortness of breath;
  • Wheezing or difficulty breathing;
  • Swelling of the face, lips, tongue or other parts of the body;
  • Rash, itching or hives on the skin.

Do not take Neo-Mercazole if you have had any of the following medical conditions:

  • Growth of the thyroid gland downwards from the neck into the chest (retrosternal goitre);
  • Serious blood disorder;
  • Severe liver disorder;
  • Airway obstruction.

Do not take this medicine after the expiry date printed on the pack or if the packaging is torn or shows signs of tampering. If it has expired or is damaged, return it to your pharmacist for disposal.

If you are not sure whether you should start taking this medicine, talk to your doctor.

Before you start to take it

Tell your doctor if you have allergies to any other medicines, foods, preservatives or dyes.

Tell your doctor if you have had any of the following:

  • Mild or moderate liver disorder;
  • Allergic reaction to thiamazole or propylthiouracil (medicines used to treat thyroid disorders).

Tell your doctor if you are pregnant or plan to become pregnant or are breastfeeding. Neo-Mercazole crosses the placenta and passes into breast milk. Your doctor can discuss with you the risks and benefits of using Neo-Mercazole if you are pregnant or breastfeeding.

If you have not told your doctor about any of the above, tell them before you start taking NeoMercazole.

Taking other medicines

Tell your doctor or pharmacist if you are taking any other medicines, including any that you get without a prescription from a pharmacy, supermarket or health food shop.

Some medicines and Neo-Mercazole may interfere with each other. These include:

  • Iodine or any preparation containing iodine;
  • Theophylline, used to treat asthma or breathing problems;
  • Medicines called anticoagulants, which are used to thin blood e.g. warfarin;
  • Prednisolone, used to treat allergic disorders, skin conditions, ulcerative colitis, arthritis, lupus, psoriasis or breathing disorders;
  • Erythromycin, used to treat bacterial infections;
  • Digitalis, used to treat heart conditions;
  • Beta-blockers, used to treat heart conditions and high blood pressure.

These medicines may be affected by Neo-Mercazole or may affect how well it works. You may need to use different amounts of your medicines, or you may need to take different medicines.

Your doctor and pharmacist have more information on medicines to be careful with or avoid while taking this medicine.

How to take NeoMercazole

Follow all directions given to you by your doctor or pharmacist carefully. They may differ from the information contained here.

How much to take

Take Neo-Mercazole exactly as your doctor has prescribed. Your doctor will tell you how many Neo-Mercazole tablets to take each day.

Be sure to keep your appointments with your doctor so that your progress can be checked. Your dose of Neo-Mercazole may change from time to time according to your progress.

How to take it

Swallow the tablets whole with a glass of water.

Do not chew the tablets.

When to take it

Take your medicine at about the same time each day. Taking it at the same time each day will have the best effect. It will also help you remember when to take it.

How long to take it

Continue taking your medicine for as long as your doctor tells you.

If you forget to take it

If it is almost time for your next dose, skip the dose you missed and take your next dose when you are meant to.

Otherwise, take it as soon as you remember and then go back to taking your medicine as you would normally.

If you are not sure what to do, ask your doctor or pharmacist.

If you have trouble remembering your dose, ask your pharmacist for some hints.

If you take too much (overdose)

Immediately telephone your doctor, or the Poisons Information Centre (telephone 13 11 26) for advice, or go to Accident and Emergency at your nearest hospital, if you think you or anyone else may have taken too much Neo-Mercazole. Do this even if there are no signs of discomfort or poisoning. You may need urgent medical attention.

The following are some symptoms which may or may not occur:

  • Skin rash;
  • Fever;
  • Extreme tiredness.

While you are taking Neo-Mercazole

Things you must do

If you are about to be started on any new medicine, remind your doctor and pharmacist that you are taking Neo-Mercazole.

Tell any other doctors, dentists and pharmacists who treat you that you are taking this medicine.

If you become pregnant while taking this medicine, tell your doctor immediately.

Tell your doctor if, for any reason, you have not taken your medicine exactly as prescribed. Otherwise, your doctor may think that it was not effective and change your treatment unnecessarily.

Tell your doctor if you feel the tablets are not helping your condition.

Be sure to keep all of your appointments with your doctor so that your progress can be checked. Your doctor may want to do some blood and other tests from time to time to check on your progress and detect any unwanted side effects.

Things you must not do

Do not take Neo-Mercazole to treat any other complaints unless your doctor tells you to.

Do not give your medicine to anyone else, even if they have the same condition as you.

Do not stop taking your medicine or change the dosage without checking with your doctor.

Do not let yourself run out of medicine over the weekend or on holidays.

After taking NeoMercazole


Keep your tablets in the bottle until it is time to take them. If you take the tablets out of the bottle they may not keep well.

Keep your tablets in a cool dry place where the temperature stays below 25°C. Do not store Neo-Mercazole or any other medicine in the bathroom or near a sink. Do not leave it in the car or on window sills. Heat and dampness can destroy some medicines.

Keep it where children cannot reach it. A locked cupboard at least one-and-a-half metres above the ground is a good place to store medicines.


If your doctor tells you to stop taking this medicine, or the expiry date has passed, ask your pharmacist what to do with any medicine that is left over.

Schedule of Neo-Mercazole

Neo-Mercazole is a prescription only medicine – Schedule 4 .

Side effects of Neo-Mercazole

Tell your doctor or pharmacist as soon as possible if you do not feel well while you are taking Neo-Mercazole. This medicine helps most people with hyperthyroidism but it may have unwanted side effects in a few people. All medicines can have side effects. Sometimes they are serious, most of the time they are not. You may need medical treatment if you get some of the side effects.

Do not be alarmed by the following list of side effects. You may not experience any of them.

Ask your doctor or pharmacist to answer any questions you may have.

Tell your doctor or pharmacist if you notice any of the following and they worry you:

These are the more common side effects of Neo-Mercazole.

Tell your doctor as soon as possible if you notice any of the following:

The above list includes serious side effects that may require medical attention.

Tell your doctor immediately or go to Accident and Emergency at your nearest hospital if you notice any of the following:

  • Liver pain, or yellowing of your skin or the whites of your eyes;
  • Sore throat, mouth ulcers, high temperature or fever, increased tendency for bruising or bleeding, extreme tiredness.

You may have to stop taking NeoMercazole.

Some tests should be performed to check for liver function or bone marrow depression before restarting your treatment. Bone marrow depression causes a reduction in the number of blood cells and reduces the ability to fight infection. If it is not treated as soon as it is detected the condition can become life-threatening.

Tell your doctor if you notice anything else that is making you feel unwell. Other side effects not listed above may also occur in some people.

Ask your doctor or pharmacist if you don’t understand anything in this list.

Do not be alarmed by this list of possible side effects. You may not experience any of them.

For further information talk to your doctor.


  1. Neo-Mercazole Consumer Medicine Information (CMI). North Sydney, NSW: Amdipharm Mercury (Australia) Pty Ltd. February 2017. [PDF]
  2. Neo-Mercazole Product Information (PI). North Sydney, NSW: Amdipharm Mercury (Australia) Pty Ltd. February 2017. [PDF]

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Posted On: 22 July, 2003
Modified On: 29 March, 2018
Reviewed On: 29 March, 2018


Created by: myVMC