What is being tested?

Salicylates are a group of drugs, including aspirin, available as both prescription and non-prescription (over-the-counter) medications. 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 it used?

The plasma salicylate concentration is used to assess aspirin dosage and, if over dosage 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 over dosage.

What does the result mean?

After over dosage 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?

• Many prescription and non-prescription medications contain salicylates in combination with other medications. Do not take more than one medication that contains salicylates at a time.
• Aspirin should not be taken with alcoholic drinks as this can increase the risk of bleeding from the stomach. If aspirin overdose is suspected, seek medical attention for the affected person.
• Salicylates, including aspirin, are included in the group of drugs called NSAIDs (nonsteroidal anti-inflammatory drugs).
• 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.
• 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 aspirin 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?

An association has been found between the use of aspirin to treat the symptoms of flu-like viral illnesses and the development of Reye syndrome, a disease characterised by acute brain damage and liver dysfunction that can be 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 over dosage, usually marked by tinnitus, nausea, and vomiting.

More information

RCPA Manual: Salicylate