Taking carbimazole with other medicines and herbal supplements

Cautions with other medicines

Taking carbimazole can affect the way certain medicines work, while some medicines are affected by your thyroid hormone levels. These levels will change as carbimazole starts to work.

For this reason, your doctor will want to review the medicines you take and possibly change the dosage.

Tell your doctor before starting treatment with carbimazole if you take any other medicines, including:

• digoxin, a heart medicine
• erythromycin, an antibiotic
• theophylline, used to treat breathing problems
• bladder medicines for urinary incontinence and other bladder problems
• blood pressure medicines called beta blockers – these are often prescribed together with carbimazole and your doctor will tell you how much to take
• medicines that help prevent blood clots (anticoagulants) such as warfarin
• steroids such as prednisolone
• clozapine, an antipsychotic

These are not all the medicines that may cause problems if you take them with carbimazole. For a full list, see the leaflet inside your medicine packet.

Mixing carbimazole with herbal remedies and supplements

Some herbal remedies and supplements can affect the way carbimazole works. This includes black cohosh, sometimes taken to help with menopausal symptoms.

There's not enough information to say that complementary medicines and herbal remedies are safe to take with carbimazole. They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.

Biotin supplements can affect the accuracy of thyroid function tests. Do not take biotin without talking to your doctor.