Cigarettes can't actually cause an allergic reaction, since they lack any allergenic proteins that would trigger your immune system. However, that's not to say that cigarettes can't cause allergy-like symptoms. In fact, the irritants in cigarettes and cigarette smoke can cause symptoms that appear very similar to those of allergic rhinitis. If you're sensitive, you may end up with a runny nose, watery eyes, coughing, sneezing and trouble breathing, much as you would if you were allergic to dust and breathed it in. People can suffer allergic reactions to tobacco leaves and plants themselves, but these allergies are rare. When you burn tobacco in a cigarette, the chances of such an allergy affecting you are pretty much zero.
Among the myriad of health risks associated with cigarettes is the chance that smoking or secondhand smoke can trigger an asthma attack in asthmatic people. To prevent the risk, asthmatics should avoid cigarette smoke whenever possible.