Coughing and sneezing are survival mechanisms which Allaah (swt) has put in place to help us ward off undesirable elements from our respiratory systems. They are signs of irritation by germs, allergens or foreign bodies in the respiratory tract while sneezing especially is an allergic reaction to dust, fumes, etc.
A “productive” cough expels sputum which may carry millions of pathogenic droplets (such as microbes causing the flu, pertussis, Tuberculosis, etc). Sneezing helps to protect/free the airway, resulting in relief from mucus congestion. Persistent cough and sneezing (+/- other symptoms) require medical attention.
So, you see, coughs and sneezes are meant to bring you comfort. Therefore, you shouldn’t use your comfort to inconvenience other people. You shouldn’t release germs to infect others. Cover your mouth and nose with your upper sleeve (the inner part of your flexed elbow), a handkerchief or a piece of tissue paper. Dispose of the handkerchief or tissue properly and immediately, wash your hands with soap and water.
Even a seemingly harmless cough could be harmful to your neighbours because your respiratory tract contains millions of commensal bacteria which are “customised” for you alone! Don’t share that cocktail with us please!
On the other hand, yawning is a sign or stress, hunger, sleepiness or laziness. You release a deep breath with a huge amount of air which could also contain droplets of germs. So you need to cover your mouth as well. Some people are fond of talking or making an exaggerated sound while yawning. This is plain uncouth and satanic!
Abu Hurairah (RA) reported: The Prophet (SAW) said, “Allaah likes sneezing and dislikes yawning. When any one of you sneezes and says ‘AlhamduliLlaah (praise be to Allaah)’, it becomes obligatory upon every Muslim who hears him to respond with ‘Yarhamuk-Allah (may Allah have mercy on you)’. Yawning is from the devil. When one of you feels like yawning, he should restrain it as much as possible, for the devil laughs when one of you yawns.” [Al-Bukhari].
PS: If someone coughs, sneezes or yawns beside you and he’s not courteous enough to close his mouth, please don’t hesitate to cover your own mouth, look away or take a few steps away from him!