1654. Vomiting delibately —even if it be out of compulsion due to a sickness or similar condition—will invalidate one’s fast. However, there is no harm if a person vomits inadvertently or involuntarily.
1655. If a person consumes something at night, which he knows will cause him to vomit involuntarily the next day, it will not invalidate his fast. The recommended precaution is that he fast the qaÃÁ of that day’s fast.
1656. If a person who is fasting can avoid vomiting, he should do so if it does not entail any harm or hardship for him.
1657. If—for example—a fly enters the throat of a person who is fasting, and he is able to remove it without vomiting, he should do so and his fast will be valid. However, if this is not possible, and it is located such that swallowing it would be counted as eating, it should be removed even if it be by vomiting. In this case his fast will be void. However, if it does not amount to eating, he should not remove it, and his fast will be deemed valid.
1658. If a person inadvertently swallows something, and it passes his throat, but he remembers before it reaches his stomach, he will not have to take it out, and his fast will remain valid.
1659. If a person is certain that should he burp, something will be expulsed from his throat, then obligatory precaution will dictate that he should avoid burping intentionally. However if he is not certain of it, there is no problem in doing so.
1660. If a person burps, causing something to enter his mouth, he should take it out of his mouth. If it is swallowed involuntarily, his fast will remain in order.