Drug Test Results: What's Normal and Abnormal?

Normal Values

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"Normal" levels vary according to the institution performing the test.

Blood can be tested for the presence and levels (amounts) of medications. Urine screening is usually reported as positive (substance is present) or negative (absent), but the level of certain substances can also be measured fairly accurately in urine.

Therapeutic levels are measured for prescribed or over-the-counter medications (see the specific medication).

Alcohol, prescription medications that are not prescribed, and illegal drugs are not normally present.

What abnormal results mean

The presence of illegal drugs or drugs not prescribed for the person indicates illicit drug use.

Elevated levels of alcohol or prescription drugs can indicate intentional or accidental intoxication and/or overdose.

Additional conditions under which the test may be performed:

• alcohol withdrawal state
• alcoholism
• drug abuse monitoring
• analgesic nephropathy
• at risk for fetal alcohol syndrome
• complicated alcohol abstinence (delirium tremens)
• delirium
• dementia
• stroke secondary to cocaine

What the risks are

The risks associated with having blood drawn are:

• excessive bleeding
• fainting or feeling lightheaded
• hematoma (blood accumulating under the skin)
• infection (a slight risk any time the skin is broken)
• multiple punctures to locate veins

Special considerations

Commonly found substances on a toxicology screen include:

• alcohol (ethanol) -- "drinking" alcohol (see Alcohol and diet)
• amphetamines
• benzodiazepines
• antidepressants
• barbiturates and hypnotics
• isopropanol -- isopropyl alcohol, rubbing alcohol (toxic) (see isopropanol overdose)
• methanol -- methyl alcohol, found in antifreeze and other substances (toxic)
• narcotics
• non-narcotic analgesics
  • acetaminophen - oral
  • anti-inflammatory analgesics - oral
• phenothiazines (antipsychotic or tranquilizing medications)
• prescription medications, any type

This test is sometimes part of an investigation for drug use or abuse; special consents, handling and labeling of specimens, or other special procedures may be required.

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Reviewed: 02/2004