The Food and Drug Administration says Dollar Tree may be selling unsafe drugs and cosmetics.

Federal authorities slapped the discount chain with a warning about selling potentially unsafe over-the-counter drugs from foreign manufacturers.

Earlier this month, the FDA sent a warning letter to Greenbrier International, which does business as Dollar Tree, saying Dollar Tree's receipt of adulterated drugs from suppliers had received separate FDA warnings and were placed on import alert. Those products included acne treatment pads and Assured brand drugs.

The FDA's letter says some of the products came from overseas companies with a pattern of violating the law, like not testing raw materials or drugs for pathogens.

The FDA also said one company contracted by Dollar Tree had "rodent feces found throughout the manufacturing facility."

"Any of these generic products that are being procured from a country which is not being regulated could have anything in it," says Nidhin Mohan of New Island Pharmacy.

Mohan also says when buying over-the-counter medication, it's best to shop at a place where a pharmacist is on hand. "It's best to go to a place where you know there are regulatory authorities who are governing them. Make sure you talk to a pharmacist before you take a medication so that you know you're safe to do so," he says.

Dollar Tree issued a statement saying, "We are committed to our customers' safety and have very robust and rigorous testing programs in place to ensure our third-party manufacturers products are safe."

Federal officials say Dollar Tree has 15 days to respond to the FDA and failure to promptly correct the violations may result in legal action, including seizure and injunction.