The Timeline of Hair Follicle Testing While a urine test typically has a detection time frame of 2-5 days, a hair follicle test can detect drug use as far back as 90 days. For this reason, it is considered a more reliable indicator of drug use than urine testing.
The simple answer is hair drug testing can go back as far as the hair shaft is long. So, if a 3cm section of hair provides an approximate 3-month overview, a 12 cm section of hair can offer an approximate 12-month profile.
Hair follicle drug testing frequently asked questions
2 Drugs in hair may be detectable for approximately 90 days, whereas drugs in urine are generally detectable for one to seven days or longer in chronic users and in oral fluid from five to 48 hours.
Hair follicle drug testing is a sophisticated method that can detect drug use over an extended period. Unlike urine or blood tests, which primarily reveal recent drug use, hair tests provide a broader detection window, reflecting drug consumption over months.
For both kinds of tests, the window of detection stretches several months back — about 3–6 months in fingernails, and about 8–14 months in toenails. (The time range for toenails is longer because toenails grow much slower than fingernails.)
Bleaching, dyeing, perming, and straightening can all impact a hair drug test result. This is because the chemicals used in these types of treatments can damage the hair shaft and alter the concentration of the drug.
Hair drug test collection
If the donor does not have head hair or if their hair is less than a ½ inch long, a specimen can be taken from other locations on the body. In order of preference, our collectors will cut the chest, underarm, leg, or facial hair to obtain a sample.
Most drugs can be detected in the hair for up to 90 days. The hair is unique among parts of the body that can be tested for drugs. Unlike urine, blood and saliva, drugs do not temporarily deposit in hair. Instead, drugs stay in the hair for the life of the hair.
Bleaching hair peroxide decreases the detectability of cocaine in user hair. Melanin–cocaine bonds are broken and cocaine is degraded into reaction products. Unbound cocaine and reaction products are washed out removing evidence of cocaine use.
How accurate are hair follicle drug tests? Hair follicle drug tests can determine whether a person has been using certain substances within the past 3 months . However, these tests cannot pinpoint the exact date of drug use because hair growth rates can vary widely among different people.
Specificity of hair testing at standard laboratory cut-offs exceeded 90% for all drugs, but sensitivity of hair testing relative to self-report was low, identifying only 52.3% (127/243) of self-disclosed marijuana users, 65.2% (30/46) of cocaine users, 24.2% (8/33) of amphetamine users, and 2.9% (2/68) of opioid users.
Given adequate hair length, hair testing can detect exposure to psychoactive substances within wide time-frames – much wider than with urine, blood, and saliva. However, hair testing cannot detect very recent exposure, and infrequent cannabis use in particular can be difficult to detect.
Hair drug tests have the longest detection period, and can typically detect drug use for up to 90 days. Depending on the drugs used, a hair sample can sometimes help determine when drug use occurred and whether it's been discontinued.
An evidentiary false positive that is the result of exogenous exposure to drug(s) in the environment. The drug positive result is not due to the ingestion or use of drug by any route of administration. Drug(s) in sweat or sebum from a source other than the user contacting hair to cause a drug positive result.
Drug detection times
Barbiturates: 2-4 days in urine and 1-2 days in blood. Benzodiazepines: 3-6 weeks in urine and 2-3 days in blood. Cannabis: 7-30 days in urine and up to 2 weeks in blood. Cocaine: 3-4 days in urine and 1-2 days in blood.
Although longer samples of hair can be tested for drug exposure over a longer period of time, a standard sample of hair from the scalp is 1.5 inches and provides information about approximately 90 days of past drug exposure.
A hair strand drug test is highly accurate – and almost impossible to cheat. The method can be used to detect virtually all drug and alcohol substances, between seven days and six months (or even longer if that's what required) after their use.
The length of time a failed drug screen stays on a record depends on the employer and the type of record. Records from a failed DOT drug test remain in the Drug and Alcohol Clearinghouse Database for five years or until a person resolves the violation through the return-to-duty process and follow-up testing.
The Timeline of Hair Follicle Testing
While a urine test typically has a detection time frame of 2-5 days, a hair follicle test can detect drug use as far back as 90 days.
Safe and Effective Ingredients
The Old Style Aloe Toxin Rid Shampoo and the Zydot Ultra Clean Shampoo contain penetrating cleansing agents that are gentle on the hair while effectively removing residual buildup, environmental pollutants, chemicals, chlorine, hard water minerals, and hair-dulling impurities.
This is because it takes about 5-10 days for drug-containing hair to grow above the scalp. Will one night of drinking show up in a hair follicle test? No, a single night of drinking will not show up in a hair follicle test. However, regular and heavy alcohol consumption can be detected in hair samples.
Testing axillary hair is advised against because many deodorants, often applied on axillary hair, may contain ingredients that lead to false FAEE levels. On the contrary, EtG is less incorporated into axillary hair compared to head hair, and therefore the results may provide an underestimation of alcohol abuse.