Hidden , you were asking about agranulocytosis....it's a rare, drug-induced condition where the white cell count is reduced, which can lead to severe infection. You may also see the term 'neutropenia',
Although it's very rare, carbimazole is one of the drugs that can cause agranulocytosis, and it's serious enough that you should have been warned about it by whoever gave you the prescription (was this an endo ?) The usual advice is that if you get a sore throat or mouth ulcers, you should stop taking the medication and arrange an immediate white cell count. Under current circs, no-one will thank you for pitching up at your GP surgery or A&E with a sore throat, so best option would be to call your GP for 111 for advice, emphasising that you are on carbimazole.
Here is some more info:
btf-thyroid.org/antithyroid...
It's important you understand this - and you should have been told - but very unlikely to cause you a problem.
Shout if you have any more questions - I was diagnosed with Graves' three years ago.