Smoking --> Stress. Cigarette smoking puts tremendous stress on our minds & bodies. People become addicted to cigarettes very quickly and when you go for awhile without smoking you get withdrawal symptoms, which can make you feel anxious. Smoking will take away this anxiety so it may feel like it reduces stress, but it is just stopping stress caused by smoking! Those who smoke also tend to smoke more when stressed.
Smoking & stress. Smoking cigarettes does serve to relieve stress for some people, but eventually leads to illness, and illness is stressful too. Find another way to relieve stress, like exercise.