Overdose Drug Test

Other names: Drug testing; Poison testing Drug screen; Toxicology assays; Emergency and Overdose Drug Testing

Overdose drug tests are ordered by doctors from accident and emergency or intensive care; they are carried out to determine levels of drugs in the blood. Tests may be carried out if a doctor suspects the patient has overdosed on illegal drugs, over the counter or prescription medication or household chemicals. Some substances and medications (including aspirin and paracetamol) only cause symptoms when they are consumed in significant amounts, while others are toxic in even the smallest concentration (these include methanol and antifreeze). Some substances, such as alcohol and illegal drugs, affect people in different ways; people who drink or take drugs on a regular basis, have a higher tolerance than those who are not used to the substance.

Why is the test used?

The test is used to measure the levels of a substance in the blood when a doctor suspects that a patient has taken an overdose or displays symptoms of intoxication. The results of the test may be used to determine the severity of the overdose and consequently the nature of the treatment.

Occasionally the results of the test are used for legal reasons; if this is the case, the test sample must be collected and stored in a special way.

Further tests may be carried out alongside the drug overdose test in order to help the doctor reach a diagnosis and determine the correct treatment.

The test is usually ordered by doctors working in accident and emergency departments; the test may be ordered when a patient displays symptoms of an overdose, including breathing difficulties, excessive sweating, changes in body temperature, changes in behaviour (becoming aggressive, agitated, paranoid, for example), tiredness and weakness, irregular heart rhythms and vomiting.

How is the test done?

The test is done by collecting and analysing a sample of blood from a vein in the arm; the blood is drawn out using a needle and then collected in a syringe. Once the sample has been collected, it will be bottled, labelled and sent away for analysis.

Urine and saliva samples may also be analysed if a drug overdose is suspected.

What do the test results mean?

The results of the test must be analysed alongside the patient’s symptoms and medical history. Some medications have a target range; however, some patients may react negatively even when they take an appropriate dose (this may be caused by interaction between different medications). In most cases, however, a patient displays symptoms as the levels of the drug in the blood reach toxic levels. If toxic levels are recorded, this usually means that the patient has taken an overdose (this may not necessarily be done consciously).

If the test results are required for a legal case as forensic evidence, the laboratory must follow strict regulations and anyone who comes into contact with sample must sign a special document, known as the ’chain of custody’.

Specific Blood Tests

Blood Test Guide

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