It helps clear blocked airways by thinning mucus in the sinuses. Because it is an expectorant or decongestant, it also helps prevent rhinitis, bronchitis and emphysema. Chillies are thus useful for colds or flu. Chili peppers contain chemical compound capsaicin. Capsaicin and its cocompounds used in the preparation of ointments, rubs and tinctures for their astringent, counterirritant and analgesic properties.