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How Long Do Drugs Stay in Your System for Hair Samples?

Hair sample drug testing is an easy, cheap, efficient, and accurate way to test for drugs in a person's system.

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Hair drug testing works because hair growth is supported by the bloodstream. The results of a hair drug test cannot be altered by shampoos or other products. The hair being tested must be cut as close to the scalp as possible for the most accurate results.


Hair drug tests can detect marijuana, cocaine, opiates, methamphetamine and phencyclidine. A federal mandate requires that drug tests screen for all five of these types of drugs.

Time Frame

Hair drug tests can detect drugs that have been in the system for 90 days, or three months.


Many consider hair testing to be much more effective than urine testing because the results cannot be as easily tampered with. The hair test can also detect drugs that have been in the system for a much longer period of time than a urine test.


In order for the hair test to be accurate the sample of hair used must contain 90 to 120 strands of hair.

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About the Author

Andrew Cohen is an aspiring writer from New Jersey who focuses on international relations and political theory. He has been writing seriously for over five years. His bachelor's degree is in political science with a minor in history.

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