In 2009, actress Brittany Murphy died from a drug overdose. What most don't realize is that it was an accident caused by combining legal prescription drugs and over-the-counter (OTC) medications to help her get through pneumonia.

She took acetaminophen and hydrocodone in prescription Vicodin; chlorpheniramine, an OTC antihistamine; and L-methamphetamine, which is in some OTC decongestant inhalers. She also had antibiotics in her system.

Many people don't know that common OTC drugs can become deadly when combined with prescription medications. And it isn't just prescription painkillers that pose a threat.

A study published in the Journal of the American Geriatrics Society illustrates this lack of awareness. Researchers found that many people who are prescribed apixaban (Eliquis) for atrial fibrillation are unaware that taking some OTC meds along with that drug can be risky.

In fact, their survey showed that 33% of those who used the medication also took OTC products daily, including nonsteroidal anti-inflammatory drugs (NSAIDs).

And 66% didn't know there was an increased risk of serious bleeding from combining NSAIDs with apixaban.

Here's how to talk to your doctors about medication interactions:

• At every doctor appointment — especially if you see more than one doctor — review your prescriptions and OTC medications, as well as any supplements and herbs you're taking. Make sure each doctor knows what others are giving you.

• Each time you're prescribed a new medication, ask your doctor about contraindications with what you're taking or might occasionally take. That includes laxatives, vitamins, OTC pain and allergy meds, etc.

• Read package inserts and labels on everything.