Dear Suresh, Smoking is hazardous to your health. There is no reason why should start this bad habbit at this age it is a very difficult habit to break once you are addicted to cigarettes. Smoking can cause lung problems such as Asthma and lung cancer. Throat cancer is another complication of smoking . SO PLEASE STOP SMOKING.. You may not have cancer but there is no reason to indulge in risky behaviour. Some Cancers are curable if treated early. Stress can cause sweating high heart rate etc.. If your symptoms persists you may have to consult a doctor. Please take care.