How many times have you taken a pill, then wondered five minutes later, "Did I take it? Did I not? Should I take another one? Should I wait till tomorrow and try harder to keep track?"

A recent study by the New England Journal of Medicine showed just how dangerous sloppiness in the pill-taking department can be.

The journal report said nearly 100,000 seniors (65 or older) make a trip to the emergency room every year, and for two-thirds of those patients, the problem is an unintentional overdose or drug interaction involving one of four medications.

The main culprits are warfarin (a blood thinner also known as Coumadin), insulin, anti-platelet drugs (to prevent heart attack and stroke) such as Plavix and aspirin, and oral diabetes medications.

Dr. David Pelini, who specializes in emergency medicine at Memorial Hermann Southwest Hospital in Houston, has suggestions for all patients who take medications daily:

1 Use a pill-dispensing box that makes it easy to tell whether you took your medication. "If you get confused," Pelini says, "it's usually more dangerous to take too much than miss a dose. If you're not sure, skip it, call the doctor's office and find out how to get back on track."

2 Fill prescriptions at one pharmacy. The staff will help you avoid potential drug interactions.

3 When a new medication is added temporarily - for example, an antibiotic for a sinus infection - insert that into your regular routine. Otherwise, you'll be back where you started, wondering, "Did I take it? Or did I forget?"

4 Keep your primary care doctor informed of any new medications or dosages prescribed by specialists.

5 Maintain a list of all your medications, dosages and when you take them. Keep this with you at all times. This is especially important in an emergency, when you might not be able to effectively communicate your health history.