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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. 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. You may also hear these medicines called tranquilizers, sleeping pills, and muscle relaxants. 

Some common medicines used to lower anxiety, relax muscles, and control seizures include:

  • Alprazolam

  • Chlordiazepoxide

  • Clonazepam

  • Clorazepate

  • Diazepam

  • Lorazepam

  • Oxazepam

Some common medicines used for promoting calmness and sleep include:

  • Temazepam

  • Triazolam

  • Flurazepam

  • Estazolam

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, such as alcohol can be fatal.

Why do I need this test?

Even if you have been prescribed 1 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

  • Low blood pressure

  • Slow or shallow breathing

  • Seizure

  • Unconsciousness

  • Cardiac arrest

You may also have this test if a healthcare provider thinks you may be 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

  • 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 flunitrazepam (Rohypnol or "roofie"), into your drink. You might also be tested if healthcare providers think you have taken benzodiazepines accidentally or as a suicide attempt. 

Different benzodiazepines have different doses, ranging from 0.5 to 50 milligrams (mg). Overdoses of 10 to 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, such as triazolam, are more likely to cause breathing problems and even death.

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 to do than blood tests. But blood tests are harder for a person to tamper with in order to hide their drug abuse.

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

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

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.   

A medicine called flumazenil 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?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

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 of the medicine from the same initial dose.

How do I get ready for this test?

You do not need to prepare for this test. But be sure your healthcare provider knows about all the medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don’t need a prescription and any illegal drugs you may use.

Online Medical Reviewer: Chad Haldeman-Englert MD
Online Medical Reviewer: Raymond Turley Jr PA-C
Online Medical Reviewer: Tara Novick BSN MSN
Date Last Reviewed: 9/1/2022
© 2000-2024 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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