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Benzodiazepines (Blood)

Does this test have other names?

Benzodiazepine drug screen

What is this test?

This is a blood test to check for a type of medicine called benzodiazepine (BEN-zoh-die-AZ-uh-peen). Benzodiazepines are medicines that depress the central nervous system. They are used to sedate patients, help them sleep, prevent seizures, ease anxiety, and relax muscle spasms. These medicines are also called tranquilizers, sleeping pills, and muscle relaxants. 

Some common antianxiety medicines, muscle relaxants, and antiseizure medicines include:

  • Alprazolam (Xanax)

  • Chlordiazepoxide (Librium)

  • Clonazepam (Klonopin)

  • Clorazepate (Tranxene)

  • Diazepam (Valium)

  • Lorazepam (Ativan)

  • Oxazepam (Serax)

Some common sedative-hypnotic medicines include:

  • Temazepam (Restoril)

  • Triazolam (Halcion)

  • Flurazepam (Dalmane)

  • Estazolam (ProSom)

These medicines are also sometimes used illegally. Street names for these medicines include "downers," "benzos," "nerve pills," "candy," and "tranks." Chronic abuse of benzodiazepines can lead to addiction. Using these medicines with other depressants like alcohol can be fatal.

Why do I need this test?

Even if you have been prescribed one of these medicines, you may need this test if you have signs or symptoms of an overdose. Signs and symptoms of overdose can include:

  • Confusion

  • Slurred speech

  • Loss of muscle control

  • Trouble thinking or talking

  • Unconsciousness

  • Low blood pressure

  • Slow or shallow breathing

  • Seizure

  • Cardiac arrest

You may also have this test if a healthcare provider thinks you are abusing the medicine illegally or without a prescription.

If you have signs as above, you may also have this test as part of a drug screen to check for other commonly abused medicines. These screens often include tests for:

  • Cocaine

  • Opioids

  • Amphetamines

  • Barbiturates

  • Benzodiazepines

  • Marijuana

  • Phencyclidine

If you are conscious and able to talk, you can give information to help your healthcare providers figure out the right test for you. For example, if you are a victim of sexual assault, you may have this test to see if someone put a benzodiazepine date rape drug, such as Rohypnol ("roofie"), into your drink.You might also be tested if healthcare providers think you have taken benzodiazepines accidentally or in a suicide attempt. 

What other tests might I have along with this test?

You may also have a glucose test to check your blood sugar. A benzodiazepine overdose alone is unlikely to cause coma or severe heart or lung function problems. If you have those symptoms, a healthcare provider may screen for other drugs and test for causes of central nervous system problems that aren't caused by medicines or drugs.

You may also have a urine test for benzodiazepines, or a urine toxicology screen for a variety of substances. Urine tests are easier than blood tests. But blood tests are harder for a person to tamper with to hide drug abuse.

Which tests you have depends on your exam, and information that you are able to provide. 

What do my test results mean?


The result of the blood test is either positive or negative. A positive result means the medicine is in your blood. A negative result means it is not. The blood test may also be able to measure the amount of medicine in your blood.   

Different benzodiazepines have different doses, from 0.5 to 50 milligrams (mg). Overdoses of 10 of 20 times the prescribed dose of some benzodiazepines can result in a mild coma, but don't cause slow or shallow breathing. Most people recover, but overdoses of fast-acting benzodiazepines like triazolam (Halcion) are more likely to cause breathing problems and even death.

A medicine called flumazenil (Romazicon) may be used as an antidote to the sedative effects of benzodiazepines. It shouldn't be used in people who have been taking benzodiazepines over a long period to control seizures. In these cases, flumazenil could cause withdrawal that could lead to death. 

How is this test done?


Does this test pose any risks?


What might affect my test results?

In older adults and people with liver disease, certain benzodiazepines may last longer in the blood. Their test results may show higher levels from the same initial dose.

How do I get ready for this test?


Online Medical Reviewer: Haldeman-Englert, Chad, MD
Date Last Reviewed: 6/1/2018