Those products included acne treatment pads and Assured brand drugs.
The letter says some of the products came from companies with a pattern of violating the law, like not testing raw material or quality.
Sharleiese Boateng, a pharmacist with Saint Francis Hospital, says when buying over-the counter medication it's best to shop at a place where a pharmacist is on hand.
"When a pharmacist is readily available then you'll always have the ability to ask any questions," she said.
In the warning letter, the FDA requests Dollar Tree implement a system to be sure they're not importing adulterated — lesser quality — drugs. They said it's Dollar Tree's responsibility.
"It's very crucial to do your homework because as I've always said, you always want to think safety over convenience," Boateng said.
Dollar Tree's company also operates the Family Dollar brand.
The company says it is committed to customers safety and they have a rigorous testing program in place to make sure third-party manufacturers are safe.
They're cooperating with the FDA and pointed out the items the FDA referenced are topical, not ingestible products.