Fiqh-us-Sunnah Volume 3, Zakaat and Fasting, Fiqh 3.135B.
Ibn ‘Abbas ruling is that: “There is no problem with tasting liquid food or something you wish to purchase.” Al-Hassan used to chew the walnuts for his grandson while he was fasting. Ibrahim also permitted that.
Chewing gum (unlike the one in vogue in the West, it has no sweetness or fragrance) is disliked. The gum must not break into pieces. Those who say that it is disliked include ash-Sha’bi, anNakha’i, the Hanafiyyah, the Shaf’iyyah, and the Hanbaliyyah. ‘Aishah and ‘Ata permit chewing, as nothing reaches the stomach and it is just like putting pebbles into one’s mouth provided it does not break into parts. If a part of it breaks off and enters the stomach, it will break the fast.
Ibn Taimiyyah says: “Smelling perfumes does not harm the fast.” Enlarging upon the subject, he says: “As for kohl, injections, drops dropped into the urethra [that is, enemas for medicinal purposes], and treatment for brain and stomach injuries, there is some dispute among the scholars. Some say that none of these break the fast, some say that all except kohl would break the fast, while others say all except the drops break the fast, or that the kohl or drops do not break the fast but that the rest do.” Ibn Taimiyyah continues: “The first opinion on this question is preferred. The most apparent conclusion is that none of them break the fast. The fast is part of the religion of Islam. Both the layman and specialist must be knowledgeable about it. If the preceding actions were forbidden by Allah and His Messenger to the fasting person because they would ruin the fast, then it would have been obligatory upon the Messenger to clarify that fact. If he had done so, his companions would have known about it and would have passed it on to the rest of the Muslims. Since no one has related that not from the Prophet, not with an authentic or a weak hadith, nor in mursal or musnad form then it must be the case that such acts do not void [the fast].” He also says: “If the ruling is one that would affect everyone or everyday matters, then the Prophet would have clarified it to a general audience. It is well-known that kohl was in common use as were oils, washing, incense, and perfume. If they broke the fast, the Prophet would have mentioned them, as he mentioned other things [that break the fast]. Since he did not do so, they belong to the class of perfumes, incense, and dyes. Incense goes through the nose and enters the head and lands on the body. Dyes or oils are absorbed by the skin and the body is refreshened by it. The case of perfumes is similar. Since these have not been [explicitly] prohibited to the fasting person, it points to the fact that using them is permissible for the fasting person and so is kohl. The Muslims during the time of the Prophet would injure themselves, either from jihad or otherwise, and would injure their stomachs or skulls. If that would have ended their fasts, it would have been made clear to them [by the Prophet].
Since that was not prohibited for the fasting person, it must not break the fast.” Ibn Taimiyyah continues: “No one eats kohl and no one causes it to enter his stomach – neither through his nose nor through his mouth. Anal enemas are also not taken as food. Indeed, it helps the body to release whatever is in the intestines and it does not reach the stomach. Any medicine that is used to treat stomach wounds or head injuries [that is taken orally] is not considered similar to food. Allah says in the Qur’an: ‘Fasting is prescribed for you as it was prescribed for those before you.’ The Prophet, upon whom be peace, said: ‘Fasting is a shield,’ and, Verily, Satan rushes through the body like the flowing of the blood [in the body]. You should constrict his rushing by hunger and fasting.’ To increase his Allah-consciousness a fasting person must not eat or drink because food and drink cause the veins to fill up with blood in which Satan circulates [in one’s body]. They become easier for Satan through eating and drinking, not from enemas, kohl, or medicines applied through the penis or used to treat stomach and brain injuries.”