DENISON, Texas -- Imodium is a seemingly harmless non-prescription drug used to treat diarrhea.

"Although it may sound benign because it's something you can buy over-the-counter, taking anything in large doses like that can be really dangerous," warned Texoma Medical Center emergency medicine Dr. David Darrigan.

Imodium and its generic equivalent loperamide are now being abused -- mainly by teens -- to get high.

"When you start taking large quantities -- over 50 pills a day -- then the effects can go to the brain and have the same effects as things like morphine, heroin, or other opiates," Darrigan said. "It can cause heart problems, believe it or not... electrical abnormalities of the heart that can lead to heart attack."

Imodium abuse has become such a problem that the Food and Drug Administration released a safety announcement about the drug, and is working with manufacturers to limit the number of doses in each package.

Darrigan said he appreciates that the FDA is raising awareness of the problem.

But Sherman resident Alecia Atchison said she's concerned that the abuse may lead to restrictions for legitimate users.

"I didn't know there was an active agent in there that could get you high," she said. "It's going to be one more thing taken off the market that people are going to need, and they are not going to be able to take it because of abusing it.".

Experts say if you notice a teenager complaining of stomach issues a lot and continually asking for Imodium, it's a sign they could be abusing the drug.