Aspirin Poisoning
Ingestion of aspirin and similar drugs (salicylates) can lead to rapid poisoning due to an overdose. The dose necessary to produce rapid poisoning, however, is quite large. A person weighing about 150 pounds would have to consume more than 30 325-mg tablets to develop even mild poisoning. An aspirin overdose, therefore, is seldom accidental.
Gradual aspirin poisoning can develop unintentionally by taking aspirin repeatedly at much lower doses. Children with fever who are given only slightly higher than the prescribed dose of aspirin for several days may develop poisoning. Adults, many of them elderly, can develop poisoning gradually after several weeks of use. The dosage of aspirin recommended to people with coronary artery disease to reduce the risk of heart attack (1 baby aspirin, ½ of an adult aspirin, or 1 full adult aspirin daily) is too small to cause gradual poisoning.
The most toxic form of salicylate is oil of wintergreen (methyl salicylate). Methyl salicylate is a component of products such as liniments and solutions used in hot vaporizers. A young child can die from swallowing less than 1 teaspoonful of pure methyl salicylate. Far less toxic are over-the-counter products containing bismuth subsalicylate (used to treat infections of the digestive tract), which can cause poisoning after several doses.
Symptoms
The first symptoms of rapid aspirin poisoning are usually nausea and vomiting followed by rapid breathing, ringing in the ears, sweating, and sometimes fever. Later, if poisoning is severe, the person can develop light-headedness, drowsiness, confusion, seizures, and difficulty breathing.
The symptoms of gradual aspirin poisoning develop over days or weeks. Drowsiness, confusion, and hallucinations are the most common symptoms. Light-headedness, rapid breathing, and shortness of breath can develop.
Diagnosis and Treatment
A blood sample is taken to measure the precise level of aspirin in the blood. Measurement of the blood pH and the level of carbon dioxide or bicarbonate in the blood also can help determine the severity of poisoning. Tests are usually repeated during treatment to reveal whether the person is recovering.
Activated charcoal reduces aspirin absorption. For moderate or severe poisoning, fluids containing sodium bicarbonate are given intravenously; unless there is kidney damage, potassium is added to the fluid. This mixture moves aspirin from the bloodstream into the urine. If the person's condition is worsening despite other treatments, hemodialysis can remove aspirin from the blood. Vitamin K may be given to treat bleeding problems.
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