Websites like WebMD can help when you’re trying to diagnose something minor. According to a recent study, they’re obviously nowhere near as helpful as talking to an actual doctor.

Researchers at Harvard ran 45 patients’ symptoms through 23 different symptom-checker websites. An average, the sites only got the diagnosis right on the first try 34 percent of the time.

The other 66 percent of the time, the researchers had to go back through — rule things out — and use their medical knowledge to help the symptom checker come up with the right diagnosis.

Which is a problem for the average person like you and me, because our medical knowledge is pretty limited. The study also found that symptom checkers just stress some people out, and make them more likely to see a doctor when they don’t need to.

The good news is, half the websites listed the right diagnosis in the top three results they spit out. But if you ever think something serious is going on, see a doctor.