All drugs carry side effects. Some are mild. Some can be very dangerous. And still some can be downright strange.

Blue vision, oily stools, amnesia and "black tongue" are just some of the strange side effects carried by prescription and the over-the-counter medications.

Should you be worried?

Many of these strange side effects are rare, which means most people won't experience them. That said, know the risks carried by any drug you use before taking it, said Dr. Manny Alvarez, managing editor of health for FOXNews.com.

Click here to read about 9 Drugs With Really Strange Side Effects.

"If you break down the side effects of medication, you can do it in three categories: severe, moderately severe and occassional," he said. "From a consumer perspective, you have to pay attention to the severe side effects."

All prescription drugs come with printed instruction explaining what the drug is used for, how to take it and what risks it carries. Read it, Alvarez said.

"It takes 30 seconds to read it, don't assume anything," he said. "If you're using an over-the-counter drug that you've never used before, read the label, including the information on side effects."

Most severe side effects stem from overuse of a medication and inappropriate dosing, i.e. taking too much. But first time users are also at risk for severe side effects. Knowing what those side effects are will help users get appropriate medical attention quickly and may prevent a life-threatening reaction, Alvarez added.