how far back can a hair test detect drugs
A hair test, also known as a hair follicle test, can detect the presence of certain drugs in a person’s system for a longer period than other types of tests, such as urine or blood tests. The detection window for a hair test depends on several factors, including:
- Length of hair: The longer the hair, the longer the detection window. Typically, a hair test can detect drugs for up to 90 days, but this can be longer if the hair is longer.
- Type of drug: Different drugs 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.
- Frequency of use: The more frequently a person uses a drug, the more likely it is to be detected in their hair.
- 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 drugs in hair tests:
- Marijuana: 30-90 days
- Cocaine: 30-180 days
- Amphetamines: 30-90 days
- Opiates: 30-90 days
- Methamphetamine: 30-120 days
- Benzodiazepines: 30-120 days
- Barbiturates: 30-120 days
Keep in mind that these are general estimates, and the actual detection window may vary depending on individual factors. It’s also important to note that hair tests can detect the presence of drugs, but they cannot determine the amount or frequency of use.
It’s worth noting that there are different types of hair tests, including:
- Standard hair test: This test typically uses a 1.5-inch sample of hair, which can detect drugs for up to 90 days.
- Extended hair test: This test uses a longer sample of hair, typically 3-6 inches, which can detect drugs for up to 6 months or more.
- Body hair test: This test uses body hair, such as arm or leg hair, which can detect drugs for up to 12 months or more.
Overall, hair tests can provide a longer detection window than other types of tests, but the actual detection window depends on several factors.
