Blood Test Guide - Drugs

The Blood Test Summary
What: Blood tests can be used to detect the presence and quantity of drugs in one’s body.
Who: Anyone can be tested for drugs; drug tests are often done for employees, suspects in a legal investigation and athletes.
Where: A blood test should be conducted in a medical facility.
When: A blood test for drugs must be done within hours of drugs being taken.
How: A medical professional will collect blood in a medical facility.
Type: Blood is drawn through a simple collection using a needle and collection tube.
Why: Blood can be tested for the presence and quantity of particular drugs.
Time: A blood collection can be done within a few minutes, and results may be made available within hours.
Language: Not applicable.
Preparation: No preparation is needed for a blood test.
Cost: Lab fees will vary across the country, though the cost is typically covered by the organization requesting the test.

By Erin Hasinger, Tests.com


Blood tests may be used to detect the presence and quantity of drugs in one’s body. Because drugs are very quickly metabolized and then eliminated from one’s body, there is a small window of time – often minutes or hours – in which a blood test is an effective measurement of the presence of drugs.


A blood test for drugs may be requested as part of a legal investigation, prior to an employment offer or as part of a random employment test, for athletic competition qualification, or during an emergency situation in which medical professionals need to find out specifically what it is in a patient’s body.


Initial drug testing is doing using enzyme immunoassay, or ELISA, which is a test that uses antibodies to detect the presence of drugs. If this test is positive for drugs, a drug class panel will then be used to identify specific drugs and how much of a particular drug is present.


Medical laboratories can test for a variety of different drugs using a drug class panel.


The five-drug class panel will test for:


  • Amphetamines, including methamphetamine
  • Cannabinoids, including THC and carboxy THC
  • Cocaine, including benzoylecgonine
  • Opiates, including codeine and morphine
  • Phencyclidine


The seven-drug class panel tests for:


  • Amphetamines, including methamphetamine
  • Barbiturates, including amobarbital, butalbital, pentobarbital, phenobarbital and secobarbital
  • Benzodiazepines, including desalkylflurazepam, diazepam, flurazepam, nordiazepam, oxazepam and temazepam
  • Cannabinoids, including THC and carboxy THC
  • Cocaine, including benzoylecgonine
  • Opiates, including codeine and morphine
  • Phencyclidine


While blood is analyzed at a medical laboratory, the blood draw must be done by a health professional. There is no preparation needed for a blood test, though drinking a glass of water prior to the blood draw may help make the draw easier.


During a blood draw, a band is wrapped around one’s upper arm to stop the blood flow, which then makes the veins in the elbow crease increase in size slightly, making it easier to insert a needle. The band may feel tight and uncomfortable.


The site of the draw is cleaned with a non-alcohol solution, and then a needle is inserted into the vein. This may feel like a sting or pinch. A tube is attached to the needle, which then fills with blood. More than one tube of blood may be collected. Once enough blood has been collected in tubes, the health professional will remove the arm band and place a cotton pad or ball over the needle site as the needle is withdrawn. Pressure is to be applied to the site for a few moments, and then it should be covered with a bandage.


There is a very low risk of side effects from a blood collection. Some may develop a small bruise at the needle site, though this can be prevented by keeping pressure on the site for several minutes immediately following the removal of the needle.


Phlebitis is a rare complication in which the vein becomes swollen. This is easily treatable by applying a warm compress several times a day.


Another risk is ongoing bleeding, generally for those with bleeding disorders. Any person with a bleeding disorder should inform a doctor or other health professional about the issue prior to having a blood test.


Blood test results can be made available within hours of collection.


For more information on using a blood test for drug detection or to find a local lab, please see Tests.com’s Blood Test Directory.