can i have a cigarette before a fasting blood test smoking or alcohol affect results? Blood Test - Do's and
Description
When smoking, the blood vessels in the skin contract, reducing the blood flow, and the ability of the incision to heal

doi: 10.1111/j.1439-0272.1991.tb02542.x
While occasional dizziness after smoking might be common, you may need to see a doctor in some cases

Passive exposure or not, many people who have a positive drug test result wonder what is going to happen next