Habitrol is designed to temporarily replace some of the nicotine that cigarettes would normally supply. While the patch is worn, controlled quantities of nicotine pass from the patch into your skin, and then into your bloodstream. Because some nicotine is left in your skin when you take the patch off, the nicotine will continue to pass into your bloodstream for several hours after patch removal. Habitrol comes in three patch sizes, which give doses of 21 mg/day (Step 1), 14 mg/day (Step 2) and 7 mg/day (Step 3). Typically, a pack-a-day smoker would wear each size for 3 to 4 weeks, gradually reducing nicotine delivery by going from Step 1 to Step 2 to Step 3.