Carbimazole for overactive thyroid
This leaflet is for parents and carers about how to use this medicine in children. Our information may differ from that provided by the manufacturers, because their information usually relates to adults. Read this leaflet carefully. Keep it somewhere safe so that you can read it again.
Name of medicine
Why is it important for my child to take Carbimazole?
An overactive thyroid gland (also called hyperthyroidism) makes too much thyroid hormone. Thyroid hormone helps to control energy levels and growth. Too much thyroid hormone can affect children's growth and may make them feel tired and anxious. Carbimazole decreases the amount of thyroid hormone released from the thyroid gland.
What is Carbimazole available as?
- Tablets: 5 mg, 20 mg; these may contain lactose
When should I give Carbimazole
Carbimazole may be given once, twice or three times each day. Your doctor will tell you how often to give it.
- Once a day: this can be in the morning OR the evening.
- Twice a day: this should be once in the morning and once in the evening. Ideally, these times are 10–12 hours apart, for example some time between 7am and 8am, and between 7pm and 8pm.
- Three times each day: this should be once in the morning, once in the early afternoon and once in the evening. Ideally, these times are at least 6 hours apart, for example 8am, 2pm and 8pm.
Give the medicine at about the same time(s) each day so that this becomes part of your child’s daily routine, which will help you to remember.
How much should I give?
Your doctor will work out the amount of Carbimazole (the dose) that is right for your child. The dose will be shown on the medicine label.
Your doctor may suggest that your child starts with a low dose. They may then increase the dose as your child gets used to the medicine and depending on how they respond to it. Your doctor will explain what to do. If you are not sure how much to give, check with your doctor, nurse or pharmacist.
It is important that you follow your doctor’s instructions about how much to give.
How should I give Carbimazole?
- Tablets should be swallowed with a glass of water, squash or juice. Your child should not chew the tablets.
- You can crush the tablet and mix it with a small amount of soft food such as yogurt, honey, or mashed potato. Make sure your child swallows it straight away, without chewing.
When should the medicine start working?
The medicine takes a while to work and you may not see any difference in your child. Your doctor will monitor your child to check that the medicine is working.
If you are not sure whether it is helping, discuss this with your doctor but continue to give the medicine.
The medicine will start to work within 1–2 hours but it may be
several weeks before your child’s symptoms start to improve.
However, you may not see much difference in your child if
they didn’t have any obvious symptoms of hyperthyroidism.
Continue to give the medicine to your child during this time.
If you are worried about whether it is helping, contact your
What if my child is sick (vomits)?
- If your child is sick less than 30 minutes after having a dose of Carbimazole, give them the same dose again.
- If your child is sick more than 30 minutes after having a dose of Carbimazole, do not give them another dose. Wait until the next normal dose.
If your child is sick again, seek advice from your family doctor, nurse, pharmacist, or hospital. They will decide what to do based on your child’s condition and the specific medicine involved.
What if I forget to give it?
If you usually give it once a day in the morning: Give the missed dose when you remember during the day, as long as this is at least 12 hours before the next dose is due.
If you usually give it once a day in the evening: If you remember before bedtime, give the missed dose. You do not need to wake a sleeping child to give a missed dose. You can give the missed dose in the morning, as long as this is at least 12 hours before the evening dose is due.
If you usually give it twice a day: If you remember up to 4 hours after you should have given a dose, give your child the missed dose. For example, if you usually give a dose at about 7am, you can give the missed dose at any time up to 11am. If you remember after that time, do not give the missed dose. Give the next dose as usual.
If you usually give it three or four times a day: You do not need to give the missed dose. Give the next dose as normal.
What if I give too much?
You are unlikely to cause harm if you give an extra dose of Carbimazole by mistake. If you are concerned that you may have given too much, contact your doctor or local NHS services (details at end of leaflet). Have the medicine or packaging with you if you telephone for advice.
Are there any possible side effects?
We use medicines to make our children better, but sometimes they have other effects that we don’t want (side effects).
Side effects you must do something about
If your child is short of breath or is wheezing, or their face, lips or tongue start to swell, or they develop a rash, they may be allergic to Carbimazole. Take your child to hospital or phone for an ambulance straight away.
If your child has a fever (temperature above 38°C), sore throat or mouth ulcers, or unusual bruising or bleeding, or feels unusually tired, contact your doctor straight away.
If your child has muscle pains, or yellowing of their skin or eyes, contact your doctor.
Other side-effects you need to know about
Your child may get some of the following side effects when they first start taking Carbimazole. These usually wear off after a few days as your child gets used to the medicine. If they are still a problem after a week, or you are worried, contact your doctor but continue to give Carbimazole.
Your child may feel sick or be sick (vomit) when they first start taking Carbimazole. Giving the medicine with some food may help. This effect should wear off after a few days as your child’s body gets used to the medicine. If it is still a problem after a week, contact your doctor for advice.
Your child may get painful joints.
They may get headaches.
Your child may develop itchiness or a mild skin rash – try applying a moisturising cream or itch relief cream. If this doesn’t help, contact your doctor, in case your child is allergic to Carbimazole.
Your child’s hair may become thinner and some may fall out. It should grow back when the medicine is stopped. Discuss this with your doctor at your next visit.
There may sometimes be other side effects that are not listed above. If you notice anything unusual and are concerned, contact your doctor. You can report any suspected side effects to a UK safety scheme at www.mhra.gov.uk/yellowcard
Can other medicines be given at the same time as Carbimazole?
- You can give your child medicines that contain paracetamol or ibuprofen, unless your doctor has told you not to.
- Carbimazole should not be taken with some medicines. Tell your doctor or pharmacist about any other medicines your child is taking before giving Carbimazole.
- Check with your doctor or pharmacist before giving any other medicines to your child. This includes herbal and complementary medicines.
Is there anything else I need to know about this medicine?
Your doctor will monitor your child to make sure the medicine is working properly. It is important to take your child for these check-ups.
- If your daughter thinks she may be pregnant, she should see her doctor as soon as possible but continue taking Carbimazole in the meantime.
General advice about medicines
- Try to give medicines at about the same times each day, to help you remember.
- Only give this medicine to your child. Never give it to anyone else, even if their condition appears to be the same, as this could do harm.
- If you think someone else may have taken the medicine by accident, contact your doctor for advice.
- Make sure that the medicines you have at home have not reached the ‘best before’ or ‘use by’ date on the packaging. Give old medicines to your pharmacist to dispose of.
- Make sure that you always have enough medicine. Order a new prescription at least 2 weeks before you will run out.
Where should I keep this medicine?
- Keep the medicine in a cupboard, away from heat and direct sunlight.
- Make sure that children cannot see or reach the medicine.
- Keep the medicine in the container it came in.
Who to contact for more information?
Your child’s doctor, pharmacist or nurse will be able to give you more information about Carbimazole and about other medicines used to treat overactive thyroid.
England: NHS 111
Scotland: NHS 24
Northern Ireland: NI Direct
Wales: NHS Direct
Tel 111 (free) or 0845 46 47 (2p per minute)111.wales.nhs.uk/
British Thyroid Foundation
01423 810 093www.btf-thyroid.org/
The Thyroid Trust (TTT, Thyroid Friends Network)
Version . © NPPG, RCPCH and WellChild, all rights reserved. Review by July 2016.
The primary source for the information in this leaflet is the British National Formulary for Children. For details on any other sources used for this leaflet, please contact us through our website, www.medicinesforchildren.org.uk.
We take great care to make sure that the information in this leaflet is correct and up-to-date. However, medicines can be used in different ways for different patients. It is important that you ask the advice of your doctor or pharmacist if you are not sure about something. This leaflet is about the use of these medicines in the UK, and may not apply to other countries. The Royal College of Paediatrics and Child Health (RCPCH), the Neonatal and Paediatric Pharmacists Group (NPPG), WellChild and the contributors and editors cannot be held responsible for the accuracy of information, omissions of information, or any actions that may be taken as a consequence of reading this leaflet.