Tobacco itself is not a drug. The main drug contained in Tobacco
is Nicotine. A deadly carcinogen known to anyone with a brain (not
including americans) to cause cancer and cancer related deaths.
The addictive drug in Tobacco is a combination of nicotine and
MAOIs (monoaminooxidase inhibitors) like acetaldehyde. Nicotine
alone, e.g. in nicotine replacement products, is not addictive.
Tobacco is a carrier for the highly addictive drug nicotine.
Once your body gets a taste for nicotine, it can quickly become a
life-long addiction. Its smoke contains over 4000 chemicals.