For many OTC drugs, listed dose covers most people

Dear Dr. Roach: In the majority of over-the-counter medication, the dosing references “adults 12 years and older” and then gives a maximum dose. I’m 6 feet, 1 inch tall and weigh 220 pounds. The average 12-year-old is 125-ish pounds. I don’t get it. Are we overdosing the 12-yearolds or limiting effectiveness for the older folks? — M.T.

Dear M.T.: The primary answer is the same overall for most over-the-counter drugs: These drugs are generally so safe that a 12-year-old won’t get close to overdose.

For aspirin in particular, the toxicity is related to the blood levels, and blood levels are directly related to size. Weight is not the only factor affecting toxicity. Age, sex, kidney and liver function, diet and some lifestyle habits all may play a role. Mild toxicity usually occurs when people take three to five times the recommended dose of aspirin.

When a drug has a large range between the minimum effective dose and a toxic dose, it is generally safe and may be appropriate for over-thecounter use.

Emergency room visits and hospital admissions are still common for accidental ingestion of aspirin. I want to re-emphasize that every person is different.

Drugs with narrow therapeutic indices need to be carefully monitored. A doctor must monitor the drug effect and toxicity, and adjust dosing as appropriate. These are not appropriate for over-thecounter use, and are often monitored by drug levels. Chemotherapy is dosed based on careful measurement of weight and height, and kidney and liver function, and still requires exceptionally close monitoring.