mine if someone is using drugs inappropriately is commonly done with urine
testing. Urine testing can detect drugs used days or even a week before the test
is performed. As false positive and false negativeresults can occur, caution
should be used when interpreting the results. When asked if they are taking any
kind of medication, individuals should include prescription, over-the-counter,
and herbal remedies. For example, traces of diphenhydramine (Benadryl)—a
commonly used antihistamine medication—will be found in urine and will cause
the person to test positive for methadone.
Whenever the result of a urine test is found to be positive for drugs, the per-
son should undergo another test for that specific medication to confirm the
results. The second test is used to identify a false positive that might be gener-
ated by the first test. Again, urine testing is done but the request is to screen only
for the specific drug identified in the first test. Blood levels may also be obtained
to determine immediate use of drugs.
Drug testing only gives evidence that the individual has used or been exposed
to a drug but does not indicate any pattern of drug use or the degree of depend-
ency. Table 4-1 shows the length of time that traces of popular drugs remain in
the body. The most commonly misused and abused drugs are listed in Table 4-2.(^68) CHAPTER 4 Substance Abuse
Drug Days Detectable in Urine
Alcohol Less than 1 day
Amphetamines Up to 1–3 days
Barbiturates Up to 1 day short acting
2–3 weeks long acting
Cocaine Up to 2–4 days
Methadone Up to 3–5 days
Marijuana
Single use Up to 3–5 days
Chronic use Up to 29 days
Opioids—Short-acting Up to 3–4 days
PCP 2–4 days
Table 4-1. Days substances remain in urine.