The cigarette company probably know this. Death from nicotine overdose is caused by paralysis of the muscles used for respiration and occurs in infants and young children who have eaten cigarettes, cigarette butts, and ashes. A few drops of pure nicotine on the tongue would quickly kill a healthy adult. Nicotine is a common ingredient in insecticides. Nicotine increases the heart rate and blood pressure thus increasing the oxygen need of the heart but not the oxygen supply.
Some people believe smoking temporarily reduces their appetite.
Tar is a complex mixture that remains on the filter after moisture and nicotine have been removed. A smoker who uses one pack of cigarettes per day will take into the bloodstream between 1.8 and 26.8 mg of nicotine, between 24 and 428 mg of tar, and between 34 and 789 mg of carbon monoxide. The amount depends on the type of cigarette smoked and the method of smoking. After quitting, most people experience withdrawal symptoms. These symptoms may include headaches, irritability, fatigue, cravings, sleep difficulties, and coughing.