Acts Which Nullify the Fast
Most important among the acts which nullify the fast are the following:
a) Sexual intercourse during the daytime breaks the fast and is a grave sin. Anyone who performs this act must atone for it by freeing a slave, if he can afford to do so; otherwise, he should fast two consecutive months, if he can. If not, then he must feed sixty poor persons if he is able to.
b) Intentionally eating or drinking also breaks the fast. If this act is done unintentionally, though, it does not harm the fast
c) The appearance of menstrual or post-partum bleeding immediately breaks the fast. Once this happens, even if it is just a few minutes before sunset, the fast is nullified and the day must be made up at a later date.
d) Ejaculation, if it comes as a result of an intentional act, breaks the fast.
e) Deliberate vomiting also breaks the fast.
f) The injection of blood or any other nourishing liquid into the body nullifies the fast.
g) Apostasy from Islam obviously breaks the fast. If a fasting Muslim says or does something which is judged to be a violation of his faith, he thereby nullifies his fast and has therefore to make up the day or days of his apostasy, if he happens to repent and return to the faith.