What Is a Toxicology Screen?
A toxicology screen is a test that determines the approximate
amount and type of legal or illegal drugs that you’ve taken. It may be used to
screen for drug abuse, to monitor a substance abuse problem, or to evaluate
drug intoxication or overdose.
Toxicology screening can be done fairly quickly. The test is most
often done using a urine or blood sample. In some cases, a sample of
saliva or hair may be used. The results can show the presence of one specific
drug or a variety of drugs at once. Further testing may be needed to
determine the exact amount of a particular drug in the body and to confirm the
What Are the Different Types of Toxicology Screens?
There are four primary types of toxicology screening:
- medical testing
- employment drug testing
- forensic analysis
- athletics testing
Most screening methods use a sample of urine to test for the
presence of drugs. In some cases, a blood, hair, or saliva sample may be used.
Why Is a Toxicology Screen Performed?
A toxicology screen may be done for various reasons. The test is
often ordered to determine if someone has taken drugs that could endanger their
health. Doctors will perform a toxicology screen if they suspect a person is
taking illegal drugs and that person is showing the following symptoms:
- panic attacks
- chest pain
- difficulty breathing
These symptoms usually indicate drug intoxication or overdose.
Employers who want to make sure their workers abstain from using
illegal substances may also order a toxicology screen. In some cases, the test
may be a normal part of the application process for certain jobs. It can also
be used to check athletes for the use of performance-enhancing drugs, such as
People who work in law enforcement might perform a toxicology
screen while investigating a car accident or sexual assault case. Officials can
also order a test for people who are being monitored for illegal drug use, such
as individuals on probation.
Other situations in which a toxicology screen may be performed
include the following:
- before receiving an organ transplant
- during pregnancy, especially when there’s a
history of substance abuse
- during treatment for certain medical conditions,
specifically those that require the use of pain medication
How Do I Prepare for a Toxicology Screen?
No special preparation is required for a toxicology screen.
However, it’s important to tell the appropriate person about any prescription or
over-the-counter medications you’re taking. Certain medications can interfere
with the test results.
How Are Samples for Toxicology Screens Obtained?
A toxicology screen often requires a urine sample. The urine is
collected in a small cup. In some cases, law enforcement or medical personnel are
present to prevent tampering. You may be asked to remove outerwear such as a
jacket, hat, or sweater and to empty your pockets as a precaution against
A blood sample may also used to screen for drugs. This type of
test involves drawing blood into one or more small tubes. During a blood test,
a healthcare professional inserts a needle into a vein and removes blood. Compared
with a urine test, a blood test is more accurate in determining the concentration
of a particular drug.
In some cases, a toxicology screen might be performed using a saliva
or hair sample. The contents of the stomach can also be screened for drugs when
doctors suspect someone has taken a drug orally.
All types of samples are sent to a laboratory for analysis.
What Types of Drugs Does a Toxicology Screen Detect?
Many substances can be discovered through toxicology screens.
Common classes of drugs that may be detected by toxicology screens include:
- alcohol, including ethanol and methanol
- amphetamines, such as Adderall
- opiates, including codeine, oxycodone, and heroin
- phencyclidine (PCP)
- tetrahydrocannabinol (THC)
Depending on the drug, it may show up in the blood or urine within
a few hours or weeks after being ingested. Certain substances, such as alcohol,
are eliminated from the body fairly quickly. Other drugs, however, can be
detected for several weeks after being used. One example is THC, which is in
What Do the Results of a Toxicology Screen Mean?
Most toxicology screens provide limited information about how
much or how often someone has taken a drug. The results of a toxicology screen
are usually positive or negative. A positive test result means that a drug or
multiple drugs are present in the body. Once your doctor identifies the
presence of a drug by screening, a more specific test may be done that can show
exactly how much of the drug is present.