Tapazole is given to suppress the thyroid.
In general, side effects are related more to the
thyroid disease being over or undertreated, not so much the medication itself, but the medication can have a few effects. Those should have come with the medication, and you can speak with the pharmacist about what medications are to avoid when taking tapazole.
Taking this medication at regular times will help him feel better.
Grave's is an auto-immune condition.