how far back can a hair strand drug test go
A hair strand drug test, also known as a hair follicle drug test, can detect the presence of certain substances in the hair shaft for a relatively long period. The detection window for a hair strand drug test depends on several factors, including:
- Hair length: The longer the hair, the longer the detection window. Typically, a hair strand drug test can detect substances for up to 90 days, but this can be extended to 6-12 months or even longer if the hair is very long.
- Hair growth rate: Hair grows at an average rate of 0.5 inches (1.3 cm) per month. This means that a 1.5-inch (3.8 cm) hair sample can reveal substance use for the past 3 months.
- Substance type: Different substances have different detection windows. For example:
- Cocaine: 2-6 months
- Marijuana: 1-3 months
- Opiates: 2-6 months
- Amphetamines: 2-6 months
- Benzodiazepines: 1-3 months
- Test sensitivity: The sensitivity of the test can also impact the detection window. More sensitive tests can detect smaller amounts of substances, which may extend the detection window.
To give you a better idea, here are some general guidelines for the detection windows of common substances in a hair strand drug test:
- Short-term use (1-2 times): 1-7 days
- Moderate use (1-2 times per week): 1-3 months
- Heavy use (daily or frequent use): 3-6 months or longer
Keep in mind that these are general estimates, and the actual detection window may vary depending on individual factors, such as hair growth rate, substance type, and test sensitivity.
