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: Nearly 100,000 seniors (65 and 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, antiplatelet drugs (to prevent heart attack and stroke) such as Plavix and aspirin, and oral diabetes medications.

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

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

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

Changes: 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?"

Doctor: Keep your primary-care doctor informed of any new medications prescribed by specialists.

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