A doctor prescribes an antibiotic for a toddler’s first ear infection. Eager to help their daughter, the girl’s parents pick up the medication on their way home. Frantically, they open the bottle and start to pour the thick pink liquid into the crying child’s ear.

The problem: It should have gone in her mouth.

This story is a classic in the health literacy community. While obvious errors like this aren’t the norm, millions of patients do make dangerous healthcare mistakes every year.

One important reason: 90 million American adults have limited health literacy. That means they have trouble finding, understanding, and using health information to make informed decisions about their health.

You can’t blame them. Even though most healthcare professionals are committed to educating their patients—including those with limited health literacy—we don’t always do a great job of it.

Here’s one example. In a 2009 New England Journal article, Ruth Parker tells the story of two parents—one of whom was a physician—who struggled to understand the instructions for their child’s flu medication. The directions were so unclear that the physician had to solve a complex equation to figure out the right dose. If a doctor has a hard time understanding such instructions, how can we expect patients to? It’s not surprising that millions of patients with limited health literacy can’t interpret medication labels correctly, or use other health information to help prevent and manage disease.

These health literacy issues have been linked to serious health consequences. Adults with limited health literacy get fewer mammograms and flu shots. They have more ER visits and hospitalizations. They cost much more to the healthcare system. And they don’t understand their health conditions as well as people who are health literate.

Health literacy should matter to you if:

1. You have a chronic condition. If you or a loved one has a chronic condition, you know there’s a lot to learn. You need to use health information to help manage conditions like diabetes, heart disease, COPD, and many others.

2. You’re a parent. Once you become a mom or dad, you’ll need to use health information to learn how to care for your child.

3. You can’t get health insurance. Patients with limited health literacy cost more, so insurers pay more. That drives up premiums, which can quickly become unaffordable.

4. You have insurance. If you pay health insurance premiums, the price is based on the cost of caring for a large group of people. The extra costs linked to limited health literacy mean the group’s costs go up. That means you pay more in premiums.

5. You’ll someday die. Every mortal adult should have advance directives. These documents list the treatments you would or wouldn’t want if you got too sick to share your wishes. They also let you name someone to make medical decisions for you if you get too sick to communicate. To understand advance directives, you need to understand some basic health information.

If you’re not in any of these groups, stop reading.

If you do fall into one of these categories, you need to educate yourself on health literacy—and learn how to become more health literate. This blog is a good place to start. We’ll help you learn what you need to know about health literacy.