Urine drug screening tests can typically detect drug use within the last 4-5 days. For example, if a test detects the presence of methamphetamine in a person's urine, this means the person is likely to have consumed or been exposed to methamphetamine at some time within the last five days. Since then, they may have stopped using the substance, but it hasn't been fully eliminated from their body yet.
However, some urine drug screening tests can react with certain commonly-prescribed medications, resulting in a false positive result – this means that the person may test positive for methamphetamine even if they haven't consumed the substance recently. In these cases, a more specific drug screening test may be required.
Drug tests don't usually screen for all drugs, simply because there are too many. This means that someone who has taken drugs in the past or currently takes drugs may 'pass' a drug test, even if they are obviously drug-affected. Many drug testing kits available online or over the counter may be inaccurate or difficult to interpret – for this reason, they are not recommended.
On its own, drug testing cannot tell you whether someone has a problematic relationship with drugs.
Although a urine drug test may help you establish whether a person has been using drugs recently, drug testing may not be the best way to 'catch someone out' as a drug user or prove they need help. It is usually better to talk to the person about their relationship with drugs.
To find out how to access support, go to the Getting Help page.