How far back does a hair follicle test detect drugs?
Most hair drug tests can detect heavy or regular use of certain illicit substances over the past three months.
Your hair grows at a rate of about one-half inch per month from the scalp. The standard 1.5-inch sample taken near the root provides a snapshot of drug use over the past 90 days.
When the hair sample is taken from slower-growing body hair (such as from the armpit) instead of the scalp, the detection window widens to up to one year.
Traces of illicit drug use may be seen in a hair sample within one week of drug use.
Hair follicle drug tests
This type of drug testing can be used to identify:
- Cocaine
- Phencyclidine (PCP)
- Amphetamines
- Opioids
- Benzodiazepines
- Marijuana
- 3,4-Methylenedioxymethamphetamine or MDMA (Ecstasy or Molly)
Hair testing does not test for alcohol use.
Unlike other drug tests, hair follicle drug tests are not recommended for testing occasional use. Instead, hair drug testing can provide a rough timeline of drug use over an extended period. These tests can help detect chronic substance use and help track the duration of drug use, and they can also indicate periods of abstinence.
Hair sample interpretation may be affected by:
- Sweat
- Bleaching or coloring hair
- Secondhand smoke
The hair sample is usually taken from the scalp as close to the back of the head as possible. Hair can also be taken from the armpit, face or other unshaven part of the body if it is unavailable on the scalp.
Related questions
- Adderall vs Vyvanse - What's the difference between them?
- What exactly is Captagon and why was it banned?
- 'Black Beauties' capsules in the 1970's - What drug was that?
References
- Hadland SE, Levy S. Objective Testing – Urine and Other Tests. Child Adolesc Psychiatr Clin N Am. 2016; 26(3): 549–565. https://dx.doi.org/10.1016%2Fj.chc.2016.02.005.
Read next
What drugs cause dilated pupils​?
Dilated pupils frequently occur as a physiological response to various substances, ranging from illicit drugs like cocaine, LSD, and ecstasy to prescription medications including antidepressants and antihistamines. This dilation results from the drug's effects on the parasympathetic and sympathetic nervous systems, which control the muscles responsible for adjusting pupil size.
Continue reading
How is Adzenys ER different to other brands of amphetamine?
Adzenys ER is an extended-release 1.25mg/mL liquid suspension compared to most other brands of amphetamine which are tablet and capsule formulations. Dyanavel XR is also an amphetamine extended-release liquid suspension, but with a strength of 2.5mg/mL. Continue reading
Is Vyvanse a controlled substance / narcotic drug?
Vyvanse is not a narcotic. Vyvanse is a schedule C-II controlled substance because its ingredient, lisdexamfetamine dimesylate, is converted to dextroamphetamine (the active agent) in the body. Dextroamphetamine is also classified as a C-II drug. Continue reading
See also:
Aimovig
Learn about Aimovig (erenumab-aooe) a once-monthly, injectable medication that can be ...
Nurtec ODT
Nurtec ODT (rimegepant) is used to treat acute migraines and prevent episodic migraines, by ...
Botox
Botox is used cosmetically to reduce facial lines and wrinkles and for medical purposes for ...
Depakote
Depakote is used to treat various types of seizure disorders. Learn about side effects ...
Topamax
Topamax (topiramate) is used to prevent seizures in adults and children and to prevent migraine ...
Emgality
Emgality (galcanezumab-gnlm) is a CGRP antagonist for the preventive treatment of migraine and for ...
Timolol
Timolol is used for angina, heart attack, high blood pressure, migraine, migraine prevention
Valproic acid
Valproic acid is used for bipolar disorder, cluster-tic syndrome, epilepsy, headache ...
Divalproex sodium
Divalproex sodium is used for bipolar disorder, borderline personality disorder, cyclothymic ...
Topiramate
Learn about topiramate, an anticonvulsant used for seizures, migraine prevention, and weight loss ...
Related medical questions
- Concerta vs Adderall - What's the difference between them?
- Does Vyvanse (lisdexamfetamine) show up on a drug test?
- How long does Fentanyl stay in your system?
- Why is fentanyl so dangerous?
- Fentanyl test strips: where to get & how to use?
- Is Prozac a controlled substance / addictive?
- What are the symptoms of a fentanyl overdose?
- What is the mechanism of action for naltrexone?
- How does fentanyl compare to heroin or other opiates?
- What is a methadone clinic / are they free?
- Is Latuda a controlled substance?
- How long do drugs stay in your system?
- What is tianeptine?
- Is Belbuca a controlled substance?
- Is Wakix a controlled substance?
- How is Arymo ER formulated to be abuse deterrent?
- Educating Students about the Dangers of Opioids
Drug information
Related support groups
- Amphetamine (93 questions, 395 members)
- Cocaine (22 questions, 286 members)
- Phencyclidine (9 questions, 13 members)
- Drug Dependence (47 questions, 541 members)