Patient leaflets and SmPCs, drug interaction checker, official and paediatric dosages, pregnancy and breastfeeding guidance, and NHS pharmacy opening hours — all in one place.
Patient leaflets and SmPCs, drug interaction checker, official and paediatric dosages, pregnancy and breastfeeding guidance, and NHS pharmacy opening hours — all in one place.
The name of your medicine is Carbimazole 5mg Tablets, Carbimazole 10mg Tablets or Carbimazole 20mg Tablets (called Carbimazole Tablets in this leaflet). Carbimazole Tablets contains the active substance carbimazole. This belongs to a group of medicines called anti-thyroid agents. Carbimazole Tablets are used to reduce the formation of thyroid hormones in adults and children with an over-active thyroid gland. This condition is called hyperthyroidism. Carbimazole is also used in more serious cases, for example, to restore the normal function of the thyroid before its partial removal by surgery. It may also be used together with other treatments for hyperthyroidism.
Do not take Carbimazole Tablets: • If you are allergic to carbimazole or any of the other ingredients of this medicine (listed in section 6). • If you have a serious blood disorder. • If you have a severe liver disorder. • If you had inflammation of the pancreas (acute pancreatitis) after administration of carbimazole or thiamazole in the past.
Warnings and precautions
Carbimazole Tablets can cause harm to an unborn baby. If you could get pregnant, use reliable contraception from the time you start treatment and during treatment. Tell your doctor straight away if you develop fever or abdominal pain, which may be signs of inflammation of the pancreas (acute pancreatitis). Carbimazole Tablets may need to be discontinued.
Take special care with Carbimazole Tablets: • If you have a swelling in your neck called an 'intrathoracic goitre'. • If you have bone marrow depression. • If you are receiving radio-iodine (for thyroid problems). • If you are of child-bearing potential. • If you are allergic to thiamazole, methimazole or propylthiouracil (other thyroid medications). • If you are lactose intolerant or have any other lactose deficiency. • If you are unable to comply with the instructions for use or cannot be monitored regularly.
Talk to your doctor or pharmacist before taking Carbimazole Tablets: • If you are pregnant, think you may be pregnant or are trying to become pregnant. • If you have mild or moderate liver problems.
If you are not sure if the above applies to you, talk to your doctor or pharmacist before taking Carbimazole Tablets.
Children Do not give this medicine to children under the age of two years because it may not be safe or effective.
Other medicines and Carbimazole Tablets Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines. This includes medicines obtained without a prescription, including herbal medicines. This is because Carbimazole Tablets can affect the way some medicines work. Also some medicines can affect the way Carbimazole Tablets work.
In particular tell your doctor or pharmacist if you are taking any of the following: • Theophylline used to treat asthma or breathing problems. • Medicines called anticoagulants, which are used to thin the blood e.g. warfarin. • Steroids such as prednisolone. • An antibiotic called erythromycin. • A medicine for heart failure called digoxin. • Medicines for high blood pressure called beta-blockers. • Any other medicine that could affect your white blood cell count.
Pregnancy and breast-feeding
If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine.
Pregnancy Carbimazole Tablets can cause harm to an unborn baby.
If you could get pregnant, use reliable contraception from the time you start treatment and during treatment. However, to reduce the possibility of any effects on your baby:
• Your doctor should prescribe the lowest dose possible. • Your treatment may be discontinued three to four weeks before you are due to give birth. Your treatment with Carbimazole Tablets may need to be continued during pregnancy if the potential benefit outweighs the potential risk to you and your unborn baby.
Breast-feeding Do not breast-feed if you are taking Carbimazole Tablets. This is because small amounts may pass into the mother's milk.
Driving and using machines You can drive when taking Carbimazole Tablets, but do not drive until you know how it affects you.
Carbimazole Tablets contain lactose and sodium If your doctor has told you that you have an intolerance to some sugars, contact your doctor before taking this medicine.
This medicine contains less than 1 mmol sodium (23 mg) per tablet, that is to say essentially 'sodium-free'.
Always take this medicine exactly as your doctor or pharmacist has told you. Check with your doctor or pharmacist if you are not sure.
• The tablets should be taken by mouth. • You can take the tablets before, during or after meals. • Each day's tablets may be divided into two (morning and evening) or three daily doses (morning, noon and night).
Adults and the elderly: The recommended starting dose for the 5mg tablets is between 4 and 12 tablets each day. The recommended starting dose for the 10mg tablets is between 2 and 6 tablets each day. The recommended starting dose for the 20mg tablets is between 1 and 3 tablets each day. Once control is achieved your doctor will gradually reduce your dose to one to three 5mg tablets each day.
Use in children The recommended starting dose is three 5mg tablets daily.
The dosage will be decided by your doctor according to your individual needs, and may be changed at intervals during treatment.
Do not change your dose without talking to your doctor first.
Your doctor may decide to add an additional tablet (l-thyroxine), to help control your condition.
Some improvement is usually felt within one to three weeks. However, full beneficial effects usually take four to eight weeks.
In order to maintain control of the thyroid gland, you may need to continue to take Carbimazole Tablets for several months. Your doctor will decide when treatment can be stopped. Your doctor may ask you to have occasional blood tests to see how you are responding to treatment.
Radio-iodine is another treatment for hyperthyroidism. If you need radio-iodine treatment your doctor will tell you to stop taking Carbimazole Tablets temporarily.
If you take more Carbimazole Tablets than you should If you take more Carbimazole Tablets than you should, contact your doctor or nearest hospital emergency department immediately. Take the medicine pack or any remaining tablets with you.
If you forget to take Carbimazole Tablets If you forget a dose, take it as soon as you remember. If it is time for your next dose, take both doses together.
If you have any further questions on the use of this medicine, ask your doctor or pharmacist.
Like all medicines, this medicine can cause side effects, although not everybody gets them.
Allergic reactions If you have an allergic reaction, stop taking Carbimazole Tablets and see a doctor straight away. The signs may include: sudden rash, swelling or difficulty in breathing.
Stop taking Carbimazole Tablets and see a doctor straight away, if you notice any of the following side effects:
• Sore throat, • Mouth ulcers, • High temperature or fever, • Significant tiredness, • Increased bruising or bleeding tendency, • You are feeling generally unwell or think that you may have an infection. • Stevens-Johnson syndrome, a serious illness with blistering of the skin, mouth, eyes and genitals • Angioedema, a serious allergic reaction with symptoms that may include swollen tongue, lips, face or throat.
In addition, if you experience any of these symptoms while taking Carbimazole Tablets you should also contact your doctor immediately:
• Muscle pain or weakness, • Nerve pain • Swelling of lymph nodes, • Swelling of glands in your mouth, • Feeling faint (low blood sugar). • Yellowing of your skin or white of your eyes (jaundice). • Kidney problems, with symptoms that include a reduction in the amount of urine passed, fluid retention, blood in the urine.
These could be signs of muscle problems, jaundice or inflammation of the liver and under medical supervision your doctor may want you to stop taking the medicine and carry out some blood tests on you.
Do not stop taking Carbimazole Tablets until you have consulted your doctor.
Carbimazole Tablets can sometime cause bone marrow depression which 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. Your doctor should carry out tests to check for bone marrow depression before restarting your treatment.
The following side effects are reported with a not known frequency (frequency cannot be estimated from the available data): • Feeling sick, • Headache • Skin rashes, including urticaria (nettle rash), • Hair loss, • Loss of taste, • Itching, • Stomach upset, • Lung problems, with symptoms that include shortness of breath or a cough, • Painful joints. • Inflammation of the pancreas (acute pancreatitis).
Reporting of side effects If you get any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme, website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.
Keep this medicine out of the sight and reach of children.
Do not use this medicine after the expiry date which is stated on the carton after EXP. The expiry date refers to the last day of that month.
PVC-Alu pack: Do not store above 25°C. Alu-Alu pack (Carbimazole 20mg Tablets only): This medicinal product does not require any special storage conditions.
Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment.
What Carbimazole Tablets contain
The active substance is carbimazole. Each 5mg tablet contains 5mg carbimazole. Each 10mg tablet contains 10mg carbimazole. Each 20mg tablet contains 20mg carbimazole.
The other ingredients are lactose monohydrate, citric acid monohydrate, croscarmellose sodium, spray aragum and magnesium stearate.
What Carbimazole Tablets look like and contents of the pack
Carbimazole 5mg Tablets are white to off-white, circular, biconvex tablets debossed 'C5' on one side and plain on the other side.
Carbimazole 10mg Tablets are white to off-white, circular, biconvex tablets debossed 'C10' on one side and plain on the other side.
Carbimazole 20mg Tablets are white to off-white, circular, biconvex tablets debossed 'C20' on one side and plain on the other side.
Carbimazole 5mg and 10mg Tablets are available in PVC- Alu blisters. Carbimazole 20mg Tablets are available in PVC-Alu or Alu-Alu blisters. Packs containing 7, 10, 14, 21, 28, 30, 56, 60, 84, 90, 100 or 112 tablets are available. Not all pack sizes may be marketed.
Marketing Authorisation Holder Morningside Healthcare Ltd. Unit C, Harcourt Way, Leicester, LE19 1WP, UK
Manufacturer Morningside Pharmaceuticals Ltd. 5 Pavilion Way Castle Business Park Loughborough, LE11 5GW, UK
This leaflet was last revised in July 2024.
Carbimazole 20mg Tablets comes as tablet containing 20mg. Always follow the dose your doctor or pharmacist has given you, and read the leaflet that comes with the medicine.
The active substance in Carbimazole 20mg Tablets is carbimazole.
Medicines with the same active substance, strength and form include: Carbimazole 20 mg Tablets, Carbimazole 20 mg tablets, Carbimazole 20 mg tablets. In total there are 4 equivalent products. They are interchangeable only if your prescriber or pharmacist says so.
This leaflet reproduces the patient information leaflet approved for Carbimazole 20mg Tablets, as published on the electronic medicines compendium (emc). The version printed inside your medicine’s packaging is the one that applies to you.
Whether a medicine is available over the counter or on prescription only depends on its licence. Check the leaflet, or ask your pharmacist — they can tell you straight away.
The text above reproduces the patient information leaflet approved for this medicine, restructured for easier reading.
Carbimazole is an anti-thyroid agent. It is indicated in adults and children in all conditions where reduction of thyroid function is required.
Such conditions are:
1. Hyperthyroidism.
2. Preparation for thyroidectomy in hyperthyroidism.
3. Therapy prior to and post radio-iodine treatment.
Carbimazole should only be administered if hyperthyroidism has been confirmed by laboratory tests.
Posology
Elderly
No special dosage regimen is required, but care should be taken to observe the contraindications and warnings as it has been reported that the risk of a fatal outcome to neutrophil dyscrasia may be greater in the elderly (aged 65 or over).
Paediatric population
Use in children and adolescents (3 to 17 years of age):
The usual initial daily dose is 15 mg per day adjusted according to response.
Use in children (2 years of age and under):
Safety and efficacy of carbimazole in children 2 years of age and under have not been evaluated systematically. Use of carbimazole in children 2 years of age and under is therefore not recommended.
Adults
The initial dose is in the range 20 mg to 60 mg, taken as two to three divided doses. The dose should be titrated against thyroid function until the patient is euthyroid in order to reduce the risk of over-treatment and resultant hypothyroidism.
Subsequent therapy may then be administered in one of two ways.
Maintenance regimen: Final dosage is usually in the range 5 mg to 15 mg per day, which may be taken as a single daily dose. Therapy should be continued for at least six months and up to 18 months. Serial thyroid function monitoring is recommended, together with appropriate dosage modification in order to maintain a euthyroid state.
Blocking-replacement regimen: dosage is maintained at the initial level, i.e. 20 mg to 60 mg per day, and supplemental L-thyroxine, 50 mcg to 150 mcg per day, is administered concomitantly, in order to prevent hypothyroidism. Therapy should be continued for at least six months and up to 18 months. Where a single dosage of less than 20 mg is recommended, it is intended that 5 mg or 10 mg tablets should be taken.
Method of administration
Oral.
Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.
Serious, pre-existing haematological conditions.
Severe hepatic insufficiency.
Patients with a history of acute pancreatitis after administration of carbimazole or its active metabolite thiamazole.
Bone marrow depression including neutropenia, eosinophilia, leucopenia and agranulocytosis has been reported. Fatalities with carbimazole-induced agranulocytosis have been reported.
Rare cases of pancytopenia/aplastic anaemia and isolated thrombocytopenia have also been reported. Additionally, very rare cases of haemolytic anaemia have been reported.
Patients should always be warned about the onset of sore throats, bruising or bleeding, mouth ulcers, fever and malaise and should be instructed to stop the drug and to seek medical advice immediately. In such patients, white blood cell counts should be performed immediately, particularly where there is any clinical evidence of infection.
Following the onset of any signs and symptoms of hepatic disorder (pain in the upper abdomen, anorexia, general pruritus) in patients, the drug should be stopped and liver function tests performed immediately. Early withdrawal of the drug will increase the chance of complete recovery.
Carbimazole should be used with caution in patients with mild-moderate hepatic insufficiency. If abnormal liver function is discovered, the treatment should be stopped. The half-life may be prolonged due to the liver disorder.
Carbimazole should be stopped temporarily at the time of administration of radio-iodine (to avoid thyroid crisis).
Patients unable to comply with the instructions for use or who cannot be monitored regularly should not be treated with carbimazole.
Regular full blood count checks should be carried out in patients who may be confused or have a poor memory.
Precaution should be taken in patients with intrathoracic goitre, which may worsen during initial treatment with carbimazole. Tracheal obstruction may occur due to intrathoracic goitre.
The use of carbimazole in non-pregnant women of childbearing potential should be based on individual risk/benefit assessment (see section 4.6).
There is a risk of cross-allergy between carbimazole, the active metabolite thiamazole (methimazole) and propylthiouracil.
There have been post-marketing reports of acute pancreatitis in patients receiving carbimazole or its active metabolite thiamazole. In case of acute pancreatitis, carbimazole should be discontinued immediately. Carbimazole must not be given to patients with a history of acute pancreatitis after administration of carbimazole or its active metabolite thiamazole. Re-exposure may result in recurrence of acute pancreatitis, with decreased time to onset.
Women of childbearing potential and pregnancy
Women of childbearing potential have to use effective contraceptive measures during treatment.
The use of carbimazole in pregnant women must be based on the individual benefit/risk assessment. If carbimazole is used during pregnancy, the lowest effective dose without additional administration of thyroid hormones should be administered. Close maternal, foetal and neonatal monitoring is warranted (see section 4.6).
This medicine contains lactose and sodium
Patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption should not take this medicine.
This medicine contains less than 1 mmol sodium (23 mg) per tablet, that is to say essentially 'sodium-free'.
Little is known about interactions.
Particular care is required in case of concurrent administration of medication capable of inducing agranulocytosis.
Since carbimazole is a vitamin K antagonist, the effect of anticoagulants could be intensified. Additional monitoring of PT/INR should be considered, especially before surgical procedures.
The serum levels of theophylline can increase and toxicity may develop if hyperthyroidic patients are treated with antithyroid medications without reducing the theophylline dosage.
Co-administration of prednisolone and carbimazole may result in increased clearance of prednisolone.
Carbimazole may inhibit the metabolism of erythromycin, leading to reduced clearance of erythromycin.
Serum digitalis levels may be increased when hyperthyroid patients on a stable digitalis glycoside regimen become euthyroid; a reduced dosage of digitalis glycosides may be needed.
Hyperthyroidism may cause an increased clearance of beta-adrenergic blockers with a high extraction ratio. A dose reduction of beta blockers may be needed when a hyperthyroid patient becomes euthyroid.
Paediatric population
Interaction studies have not been performed in paediatric patients.
Women of childbearing potential
Women of childbearing potential have to use effective contraceptive measures during treatment (see section 4.4).
Pregnancy
Carbimazole crosses the placenta but, provided the mother's dose is within the standard range, and her thyroid status is monitored; there is no evidence of neonatal thyroid abnormalities.
Studies have shown that the incidence of congenital malformations is greater in the children of mothers whose hyperthyroidism has remained untreated than in those who have been treated with carbimazole.
However, cases of congenital malformations have been observed following the use of carbimazole or its active metabolite methimazole during pregnancy.
A causal relationship of these malformations, especially choanal atresia and aplasia cutis congenita (congenital scalp defects), to transplacental exposure to carbimazole and methimazole cannot be excluded.
Therefore, the use of carbimazole in non-pregnant women of childbearing potential should be based on individual risk/benefit assessment (see section 4.4).
Cases of renal, skull, cardiovascular congenital defects, exomphalos, gastrointestinal malformation, umbilical malformation and duodenal atresia have also been reported.
Therefore, carbimazole should be used in pregnancy only when propylthiouracil is not suitable. If Carbimazole is used in pregnancy the dose of Carbimazole must be regulated by the patient's clinical condition. The lowest dose possible should be used, and this can often be discontinued three to four weeks before term, in order to reduce the risk of neonatal complications.
The blocking-replacement regimen should not be used during pregnancy since very little thyroxine crosses the placenta in the last trimester.
Hyperthyroidism in pregnant women should be adequately treated to prevent serious maternal and foetal complications.
Carbimazole is able to cross the human placenta.
Based on human experience from epidemiological studies and spontaneous reporting, carbimazole is suspected to cause congenital malformations when administered during pregnancy, particularly in the first trimester of pregnancy and at high doses.
Reported malformations include aplasia cutis congenita, craniofacial malformations (choanal atresia; facial dysmorphism), exomphalos, oesophageal atresia, omphalo-mesenteric duct anomaly, and ventricular septal defect.
Carbimazole must only be administered during pregnancy after a strict individual benefit/risk assessment and only at the lowest effective dose without additional administration of thyroid hormones. If carbimazole is used during pregnancy, close maternal, foetal and neonatal monitoring is recommended (see section 4.4).
Breast-feeding
Carbimazole is secreted in breast milk and, if treatment is continued during lactation, the patient should not continue to breast-feed her baby.
Fertility
No fertility data available
Not relevant.
Adverse reactions usually occur in the first eight weeks of treatment. The most frequently occurring reactions are nausea, headache, arthralgia, mild gastric distress, skin rashes and pruritus. These reactions are usually self-limiting and may not require withdrawal of the drug.
The undesirable effects are listed below by system organ class and the following frequency convention: Not known (cannot be estimated from the available data).
Blood and lymphatic system disorders
Bone marrow depression including neutropenia, eosinophilia, leucopenia and agranulocytosis has been reported. Fatalities with carbimazole-induced agranulocytosis have been reported.
Rare cases of pancytopenia/aplastic anaemia and isolated thrombocytopenia have also been reported. Additionally, very rare cases of haemolytic anaemia have been reported.
Patients should always be warned about the onset of sore throats, bruising or bleeding, mouth ulcers, fever and malaise and should be instructed to stop the drug and to seek medical advice immediately. In such patients, white blood cell counts should be performed immediately, particularly where there is any clinical evidence of infection.
Generalised lymphadenopathy.
Immune system disorders
Angioedema and multi-system hypersensitivity reactions such as cutaneous vasculitis, liver, lung and renal effects occur.
Endocrine disorders
Insulin autoimmune syndrome (with pronounced decline in blood glucose level).
Nervous system disorders
Headache, neuritis, polyneuropathy.
Vascular disorders
Bleeding.
Gastrointestinal disorders
Nausea, mild gastrointestinal disturbance.
Loss of sense of taste has been observed.
Acute salivary gland swelling,
Acute pancreatitis.
Hepatobiliary disorders
Hepatic disorders, including abnormal liver function tests, hepatitis, cholestatic hepatitis, cholestatic jaundice and most commonly jaundice, have been reported; in these cases carbimazole tablets should be withdrawn.
Skin and subcutaneous tissue disorders
Skin rashes, pruritus, urticaria. Hair loss has been occasionally reported.
Severe cutaneous hypersensitivity reactions have been reported in both adult and paediatric patients, including Stevens-Johnson syndrome (very rare including isolated reports: severe forms, including generalised dermatitis, have only been described in isolated cases).
Musculoskeletal and connective tissue disorders
Isolated cases of myopathy have been reported. Patients experiencing myalgia after the intake of carbimazole should have their creatine phosphokinase levels monitored.
General disorders and administration site conditions
Fever, malaise.
Injury, poisoning and procedural complications
Bruising
Paediatric population
Frequency, type and severity of adverse reactions in children appear to be comparable with those in adults.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme, website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
Symptoms
No symptoms are likely from a single large dose.
Treatment
No specific treatment is indicated.
Ask anything about Carbimazole 20mg Tablets. The assistant answers only from this leaflet — if the leaflet does not cover it, it will say so. It does not give medical advice.
Answers come from the patient leaflet published on the electronic medicines compendium (emc). They are not medical advice. Ask a pharmacist or your GP if you are unsure. For urgent help call NHS 111, or 999 in an emergency.
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