Cigars are harmful to the human body because they contain a variety of harmful substances that affect human health. 1. Cigars contain a certain amount of nicotine, which, if inhaled for a long time or in excess, can cause throat discomfort in the less severe cases, and in the more severe cases, can lead to lung cancer and other lung diseases. 2. Moreover, when smoking cigars, cigar smokers tend to let the smoke linger in their mouths without inhaling the cigar smoke into their lungs, therefore, the prevalence of oral cancer, tongue cancer or pharyngeal cancer among cigar smokers will be higher. 3. Smoking cigar smoke emits several tobacco-specific nitrosamines, and these chemicals have been shown to be highly carcinogenic. In addition, cigar wrappers are not able to burn completely due to their poor breathability. This leads to higher concentrations of nitrogen oxides, ammonia, carbon monoxide and tar during the combustion process, all of which are more harmful to the human body. Both cigar and cigarette smokers are more likely to suffer from these diseases than non-smokers. Therefore, it is recommended not to smoke cigars or cigarettes in excess or for a long period of time.