Drugs are prescribed in a variety of units of measure, units that are usually notated using abbreviations or symbols -- offering a host of opportunities for disaster. All it takes is a misplaced decimal point and 1.0 mg becomes 10 mg, a tenfold dosing error that could cause a fatal overdose.
Some of the most extreme dosage mistakes occur when someone mistakes a dose in milligrams with one in micrograms, resulting in a dose 1,000 times higher. This mostly happens in the hospital with IV drugs, but it's been known to happen with outpatient meds as well. Insulin, the primary treatment for diabetes, causes some of the worst medication errors because it's measured in units, abbreviated with a U, which can look like a zero or a 4 or any number of other things when scribbled.
Another common problem, says pharmacist Bona Benjamin, director of Medication-Use Quality Improvement at the American Society of Health-System Pharmacists, is getting the frequency wrong -- so, say, a drug that is supposed to be given once a day is given four times a day.
How to avoid it: Make sure your doctor's writing is clear on the original prescription; if you can't read the dosage indicated, chances are the nurse and pharmacist will have difficulty as well. When you pick up the prescription from the pharmacy, ask the pharmacist to check the dosage to make sure it's within the range that's typical for that medication. In the hospital, when a nurse is about to administer a new medication, ask what it is and request that he or she check your chart to make sure it's the right one for you and that the dosage is indicated clearly. Don't be afraid to speak up if you think you're about to get the wrong medicine or the wrong dose.
