At a glance

Also known as

Salicylates

Why get tested?

To guide hospital treatment if aspirin overdosage is suspected.
Aspirin therapy of chronic inflammatory conditions is rarely used now.

When to get tested?

Usually in hospital after an overdose.

Sample required?

A blood sample drawn from a vein usually in an arm

What is being tested?

The plasma concentration of salicylic acid (the active part of aspirin) is being measured as this produces the undesirable side effects, notably damage to the stomach, including ulcers and bleeding, and tinnitus (ringing in the ears).

How is the sample collected for testing?

Normally from a vein in the arm by use of a needle and syringe.

The Test

How is it used?

The plasma salicyate concentration is used to assess aspirin dosage and, if overdosage is diagnosed, to guide hospital treatment of aspirin poisoning.

When is it requested?

Either to monitor dosage during long-term aspirin treatment, or to help diagnose overdosage.

What does the test result mean?

After overdosage the result has to be interpreted by the hospital doctor who takes into account other factors such as the time the overdose was taken and whether other drugs are present.

Is there anything else I should know?

Aspirin is used in adults to bring down a fever or as an analgesic (pain remover) for a toothache or head ache . For these purposes  the dose is 300 – 600 mg/day. The dose may be repeated after 4 hours and the maximum dose should not exceed 4 g/24 hours.

Aspirin is usually not used to treat chronic pain today.

Low dose aspirin, 75 – 150 mg/ day is given to prevent  heart attacks and strokes. Aspirin should not be taken long-term without consulting your doctor. It is not monitored at this low dose.

Aspirin should NEVER be given to children under 12 years of age unless directed by a doctor. Aspirin should not be taken with alcoholic drinks as this increases the risk of bleeding from the stomach. If aspirin overdosage is suspected you should seek medical help. Ibuprofen (Neurofen) or paracetamol (Panadol) are safer treatments than aspirin for short-term problems such as headache.

Common Questions

Will taking aspirin at normal dosage damage my health?

Regular asprin consumption should only be adopted under the supervision of your doctor. Low-dose aspirin (50 milligrams or so per day), used to reduce the risk of heart attack is generally safe.

Why should aspirin not be given to children?

Rarely in children aspirin causes a type of liver disease known as Reyes Syndrome which may prove fatal. Aspirin should never be given to children unless directed by a doctor. It is sometimes used to treat conditions in which no other drug is as effective.

Why is the test sometimes referred to as 'salicylates' and not simply 'salicylate'?

Other much less commonly used drugs than aspirin such as methylsalicylate (Oil of Wintergreen) may give similar results in the test, but this is of no consequence normally as the meaning of the result is the same.

Why is the INR test sometimes requested in people taking aspirin?

Aspirin acts to prevent blood clotting and INR may be measured to ensure that this effect is not too pronounced, especially if other anticoagulant drugs are also being taken.

What is salicylism?

Salicylism is the name given to the toxic effects salicylates experienced after overdosage, usually marked by tinnitus, nausea, and vomiting.

Last Review Date: October 27, 2011