My thyroxine goes by the name of 'Levothyroxine'. I have to admit that I've been taking it so long I had stopped reading the manufacturer's leaflet every time I started a new pack, so I have checked the current version and it is full of warnings. I am to tell my doctor if I am suffering from various conditions including pregnancy, diabetes, heart problems, high blood pressure and/or an underactive adrenal gland (I should have thought it would be my doctor telling ME these things). I am also to tell the doctor if I am taking medicines for these conditions (surely the doctor would know?), or for stomach ulcers, heartburn, kidney disease or epilepsy, as well as oestrogen, testosterone, iron pills and calcium carbonate (these at least I could be taking as food supplements without a doctor's prescription). It also mentions aspirin and phenylbutazone, but doesn't mention ibuprofen or grapefruit.
It's more complicated than I thought.