Can hair testing differentiate between one-time and frequent use?

Hair testing can indicate patterns of drug use, but it can’t always distinguish between one-time and frequent use with absolute precision. Because drug metabolites accumulate in the hair over time, frequent or repeated use is more likely to produce higher levels of metabolites along the hair shaft. In contrast, a single use may result in levels that are too low to be detected. However, factors like the amount used, the drug type, and the person’s metabolism can all influence the outcome.