What is Benzodiazepines Blood test?

Benzodiazepines are a group of medicines that are used to treat certain brain disorders. They act as tranquillisers, muscle relaxants and sedatives and are prescribed to patients with anxiety. Benzodiazepines also help prevent seizures, promote sleep, sedate patients and heal muscle spasms. However, continued use of the drug without a break can lead to addiction.

Some people abuse benzodiazepines for recreational purposes. The street names for benzodiazepine are ‘nerve pills’ or ‘downers’.

A benzodiazepines blood test also goes by the name benzodiazepine drug screen. The test not only helps to know the levels of benzodiazepines in the blood, but is also useful as an overdose or toxicology screen. High doses of this medicine have the ability to put a person in a coma-like state. Therefore, it is important for doctors to know if a person is taking the right dose. Some doctors may also order a blood sugar test along with this test or a urine test for benzodiazepines. Usually, the test is a qualitative test, which means the test can only detect the presence of the drug in the blood and not the amount.

(Read more: Benzodiazepines urine test)

  1. Why is a Benzodiazepines Blood test performed?
  2. How do you prepare for a Benzodiazepines Blood test?
  3. How is a Benzodiazepines Blood test performed?
  4. What do Benzodiazepines Blood test results mean?

Doctors order a benzodiazepines test as part of a drug screen or toxicology screen for one of the following reasons:

  • To see if a person has been taking the recommended dose of the medicine
  • To determine the cause of drug toxicity in a person
  • For employment or legal purposes, to know if a person is taking the drug illicitly or without prescription from a certified doctor

The following are the signs of overdose or drug toxicity, which may prompt a doctor to order this test:

Some types of benzodiazepines are used as date rape drugs. So, in cases of sexual assault, a doctor may order this test to know if the person had been drugged before the assault.

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You do not require much preparation before this test. However, some medical conditions are known to affect the results of this test. Inform the nurse or laboratory technician if you have or had any illness recently. It is also necessary that you tell them if you are taking any prescription, non-prescription medicines or herbs and vitamin supplements.

This test can be performed at any time of the day. A nurse or laboratory technician will use a sterile needle to draw a small amount of blood from a vein in your arm - they may first tie a band (tourniquet) around your upper arm to locate the right vein. The blood sample will be collected in a test tube and will immediately be sent to the laboratory for testing. 

After the blood is taken, you may get a small bruise at the needle insertion site - it will fade away soon. If the bruising does not go away, please consult your doctor. 

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Normal results:

A normal result is reported as negative. It indicates that no benzodiazepine was not found in the given blood sample. The drug is usually present in the form of a metabolite - the substance formed after the body has broken down the main drug molecule - in the blood. 

A negative result may not always mean that a person has not taken the drug; it may be that the amount of the drug metabolite was too low to be detected in the test.

Abnormal results:

An abnormal result in a benzodiazepines blood test is reported as positive. It means that benzodiazepine metabolite was detected in the given sample. A positive result; however, does not tell how much of the drug is present in your blood. It is merely an indicator of drug intake. Nonetheless, some laboratories may have elaborate procedures to know the amount of drug present in the blood too.

Sometimes, a false-positive result may also occur in a toxicology screen due to interference from other medicines taken, such as medicines for cold, cough, pain and infections. Talk to your doctor if you are worried about the test outcome or procedure. He/she will be able to explain precisely what the result means based on your age, sex and health history.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.


  1. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; Benzodiazepines (Blood)
  2. Harvard Health Publishing. Harvard Medical School [internet]: Harvard University; Benzodiazepines (and the alternatives)
  3. Provan D. Oxford Handbook of Clinical and Laboratory Investigation. Poisoning and Overdose. 4th ed. United Kingdom: Oxford University Press. 2018. Pp:700. Chapter 11.
  4. Wilson DD. McGraw-Hill’s Manual of Laboratory & Diagnostic Tests. McGraw-Hill. 2008. Pp:560.
  5. National Health Service [internet]. UK; Blood Tests
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