Are you talking about you smoke cigarettes? That's not going to affect your drug test. They ARE looking for weed & other narcotics that may be in your body. If you don't do any of those you should be fine.
here are the main things they look for....
Cannabinoids (marijuana, hash)
Cocaine (cocaine, crack, benzoylecognine)
Amphetamines (amphetamines, methamphetamines, speed)
Opiates (heroin, opium, codeine, morphine)
Phencyclidine (PCP)
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Expanded tests look for these in addition...
Barbiturates (Phenobarbital, Secobarbitol, Butalbital)
Hydrocodone (Lortab, Vicodin)
Methaqualone (Quaaludes)
Benzodiazepines (Valium, Xanax, Librium, Serax, Rohypnol)
Methadone
Propoxyphene (Darvon compounds)
Ethanol (Alcohol)
MDMA (Ecstasy)
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Urine Tests
Are the least expensive of the test methods (~$7-$50 for home version).
Are considered an intrusive method of testing.
Can be done at home (for example by parents) though require lab verification for accurate results.
Detect use primarily within the past week (longer with regular use).
Can be affected by abstaining from use for a period of time before the test.
Are often temperature tested to insure sample integrity.