1581. If a person who is fasting intentionally eats or drinks something, being well aware that he is fasting, his fast will be rendered void, regardless of whether it is something that is usually consumed, such as bread and water, or not usually consumed, such as sand and tree sap, and regardless of whether it is a significant amount or not. In fact, if a person expels a fluid from his mouth and then puts it back into his mouth, eventually swallowing it, his fast will be void, unless the fluid dissolves in his saliva in a manner that it is no longer considered to be external fluid.
1582. If a person realizes that it has dawned whilst he is eating, he must remove the morsel from his mouth. If he intentionally swallows it, it will void his fast, and in accordance with the instructions that will follow, the kaffÁrah will also become obligatory on him.
1583. If a person who is fasting eats or drinks something inadvertently, his fast does not become void.
1584. There is no harm in infusing medicine into the body through injection, or anesthetizing a part of the body using the same process. The recommended precaution is that a person who is fasting should avoid injections which are given in lieu of food or water
1585. If a person who is fasting, intentionally swallows the food that has remained between his teeth, well aware that he is fasting, his fast will be rendered void.
1586. A person who intends to fast does not have to floss his teeth prior to the adhÁn of fajr. However, if he is certain or satisfied that the food leftover between his teeth will be swallowed through the course of the day, yet fails to floss his teeth, and later a part of it is swallowed, his fast will be deemed void.
1587. Swallowing one’s saliva does not invalidate the fast, even if its secretion is a result of imagining sweet or sour foods.
1588. There is no harm in swallowing one’s nasal mucus or respiratory phlegm, as long as it has not entered the mouth. If it has, obligatory precaution dictates that one should not swallow it.
1589. If a person who is fasting experiences thirst to a degree that he fears for his life, it is obligatory on him to drink an amount of water that is just enough to save his life. His fast however will become void. Should this occur in the month of Ramadan, he should avoid committing any of the acts that invalidate a fast for the rest of the day. Similarly, if he fears that by not drinking water, he will be afflicted with a significant harm, or doing so will entail a hardship that is conventionally not bearable, he may drink water in both these cases to the extent that the fear of the harm or hardship is lifted.
1590. Chewing food for a child or a bird, tasting the food or any similar act in which the food does not usually reach the throat, will not invalidate one’s fast, even if the food accidentally reaches the throat. However, if a person knows in advance or attains satisfaction that it will reach his throat, it will invalidate his fast and he will have to perform its qaÃÁ. In the event that it does in fact reach the throat, paying the kaffÁrah will also become obligatory on him.
1591. A person cannot break his fast due to weakness. However, should the weakness be to such a degree that it would be unbearable—in the common understanding—for the person, then there is no harm in breaking it.