It must not be used in pregnancy unless the mother’s life is at risk. Breastfeeding must be ceased before use but it may be used with caution in children. Regular blood tests for thyroid gland function and blood chemistry and, and checking of blood pressure are essential. Do not take it if suffering from porphyria.
Side effects may include tiredness, incoordination, dizziness, rash, nausea and less commonly confusion, vomiting and a fever may occur. Interactions are possible with dexamethasone, anticoagulants and hypoglycaemics (used for diabetes). An overdose may cause incoordination, sedation, difficulty in breathing and coma, but death is unlikely.