Hair drug testing is one of the most reliable ways to detect long-term drug use — but what exactly can it detect?

A longer window.

Hair tests detect drug use up to 90 days back, making them ideal for employers, families, and individuals seeking clarity over time.

Common substances detected:

• Marijuana (THC)
  
  

• Cocaine
  
  

• Opiates (heroin, morphine, codeine)
  
  

• Amphetamines (Adderall, methamphetamine)
  
  

• Benzodiazepines (Xanax, Valium)
  
  

• Methadone
  
  

• Ecstasy (MDMA)
  
  

• Barbiturates
  
  

• PCP
  
  

• Fentanyl (if included)
  
  

• Oxycodone
  
  

• Buprenorphine
  
  

Why fentanyl matters:

This potent opioid is increasingly mixed into street drugs without users’ knowledge. If you’re concerned about accidental exposure, look for tests that include fentanyl — not all do.

Accuracy:

Lab-processed hair tests are highly accurate, hard to cheat, and not impacted by shampoo or hair color.

Sources:

Quest Diagnostics. “Hair Drug Testing.” https://www.questdiagnostics.com/home/physicians/testing-services/by-test-name/hair-drug

American Addiction Centers. “Hair Drug Testing Facts.” https://americanaddictioncenters.org/rehab-guide/faq/hair-drug-tests

National Institute on Drug Abuse. “Fentanyl DrugFacts.” https://nida.nih.gov/publications/drugfacts/fentanyl