What Drugs Are Tested for in a Hair Drug Test?

Hair drug testing analyzes 90 to 120 strands to determine the presence of drugs. Drugs embed themselves into the hair shaft, which is not significantly changed by external hair products or chemicals. According to the Mayo Clinic, hair testing uses the most recent 1.5 inches of hair growth, or the last 90 days, and provides information on the ingestion of chemicals when urine tests provide limited information regarding drug use in the last two to three days, in some cases. Hair testing will not screen for alcohol use.

Cocaine

• Cocaine and its derivatives such as crack cause a feeling of increased energy and overall well-being. However, this addictive illegal drug can cause paranoia and heart damage with continued use and lead to eventual death. Cocaine is usually smoked, injected or snorted, depending on its form. Although cocaine is water-soluble and flushes through the urine quickly, the keratin in hair stores cocaine and all other drugs for 90 days or longer.

THC

• THC is delivered through hash, or, more commonly, marijuana. Teens and young adults often prefer marijuana, the most commonly abused substance after nicotine and alcohol. Use hampers learning and coordination and might result in paranoia.

Opiates

• Opiates come from the poppy plant and act to depress the central nervous system. Available in both legal and illegal forms, derivatives include heroin, opium, the codeine family, prescription drugs including Demerol and Percodan, and morphine. Doctors often limit prescriptions of these powerful pain relievers to end-of-life situations, extreme cases and brief time frames. Indications of use for this depressant can include sweating, vomiting, cramping, irritability, sleepiness and loss of appetite.

Amphetamines

• Amphetamines --- commonly called crank, speed and methamphetamine --- all fall under the same category. The use of these drugs, in both street and prescription forms, can lead to a variety of physical and mental health issues. Increased heart rate, sleeplessness, paranoia and weight loss often result from the use of these drugs.

PCP

• The hallucinogen phencyclidine, also known as PCP or angel dust, causes irrational and unpredictable behavior in the user. Users inject or snort the drug. Long-term use can result in severe hallucinations and extreme paranoia.

Other Drugs

• Hair testing can detect other drugs such as antidepressants, nicotine, mescaline and methadone. However, the methodology for testing is not stable for these substances, and as of March 2011, further research is pending.