Information Living with thyroid disorders Antithyroid drugs FAQs My child has missed a dose. Is this dangerous? Although it’s important to make sure your child takes their antithyroid drugs regularly, missing a dose will not affect them. You should not double the dose if they have missed taking a tablet. Will I have to pay for my child’s prescriptions? Currently children under the age of 16, and young people aged 16, 17 or 18 who are in full-time education automatically get free prescriptions for all their medications in England. Charging for prescriptions has been abolished in Wales, Scotland and Northern Ireland. How will I know if my child is on the right dose? Your child’s symptoms should disappear once they are on the right dose. Blood tests will also show whether their levels of TSH and thyroid hormones are within the correct reference range. Can my child stay on antithyroid drugs long term? If the overactivity has not been cured after a course of treatment (18 months to three years) your child’s doctor will discuss other treatment options – surgery or radioactive iodine. Antithyroid drugs carry a small risk of potentially dangerous side effects. What should I do if my child has a sore throat or mouth ulcers? If your child has a fever, sore throat or mouth ulcers you should not give them any more carbimazole (or propylthiouracil tablets). You should immediately take them to their GP or the nearest Accident and Emergency department so that a full blood count can be carried out. You should take the medication with you. How common is liver injury? It is very rare, but if you notice any yellowing of the eyes or skin you should take your child to see their doctor immediately.