how far back can a hair follicle test go
A hair follicle test, also known as a hair drug test, can detect the presence of certain substances in the body for a longer period than other types of tests, such as urine or blood tests. The detection window for a hair follicle test depends on several factors, including:
1. Length of hair: The longer the hair, the longer the detection window. Typically, a hair follicle test can detect substances for up to 90 days, but it can go back as far as 6-12 months or even longer if the hair is long enough.
2. Type of substance: Different substances have different detection windows. For example, marijuana can be detected for up to 90 days, while cocaine can be detected for up to 6 months.
3. Frequency of use: The more frequently a substance is used, the longer it can be detected in the hair.
4. Sensitivity of the test: The sensitivity of the test can also affect the detection window.
Here are some general guidelines for the detection windows of common substances in a hair follicle test:
* Marijuana: 30-90 days
* Cocaine: 30-180 days
* Opiates: 30-180 days
* Amphetamines: 30-90 days
* PCP: 30-180 days
* Barbiturates: 30-180 days
* Benzodiazepines: 30-180 days
It’s worth noting that a hair follicle test can detect substances that were used even if the person has been abstinent for a period of time. This is because the substances can remain in the hair shaft for an extended period.
It’s also important to note that a hair follicle test is not foolproof, and there are some limitations and potential false positives to consider. For example, a person may test positive for a substance if they have been exposed to it through secondhand smoke or if they have used a product that contains the substance.
