Smoking does not normally cause headaches. If headaches occur when smoking, they may be caused by the following: 1. The main component in cigarettes is nicotine, and some people are allergic to nicotine. If there is an allergy, headaches, dizziness, nausea, and other allergic symptoms may also occur. 2. Nicotine has obvious excitatory and vasodilating effects, and when excited, it can cause an increase in the secretion of pentothal in the body, leading to headache, dizziness, nausea, vomiting, and also accompanied by palpitations and other discomforts. 3. If the scalp blood vessels are dilated, patients may also experience headache, dizziness, nausea, vomiting, and some patients may also experience other discomforts. If patients experience headache when they smoke, it is recommended that they try to quit smoking.