The 40-flavor system was developed by the family owned Center Pharmacy in northwest Washington, D.C.
"It's eliminated these battles between parents and children," said Haas, who wishes it was around when his teenage sons were young.
Flavored medicine is not a new concept. Some drug companies have been doing it for years, said Dr. J. Ramsay Farah, a pediatrician with offices Hagerstown and Boonsboro.
But FlavorX may help people who use unflavored generic medicines and children who are picky about what kind of flavor they will swallow, he said.
"It's very crucial for patients to take their medicine, so anything that leads to compliance is a good thing," he said.
Haas first heard about flavored medicine last January at a pharmacy convention and has been using it almost a year.
Although the response has not been overwhelming, some parents say it has eased their burden.
Karen Hartle of Boonsboro used to have a real hard time getting her son, Troy, 5, to take medicines.
"You couldn't get it in him. He forced his mouth closed, and if you got it in, he'd spit it back up onto his shirt," said Hartle, 30.
Now he takes his cherry-flavored medicine with no problem, she said.
Travis Nalley, 3, prefers grape or bubble gum, said his mother, Becky Nalley, 25, of Boonsboro.
"Without the flavoring, it's really hard to get kids to take medicine. When it's flavored, they take it like it's juice or something," she said.
"It's like Baskin and Robbins," said Harold Kramm, one of the owners of Center Pharmacy. He said the medicines aren't so appealing that kids would want to take them on their own.
They still leave an aftertaste, which is why Haas tells his customers to take a drink of water after the dose.
Haas encourages kids to keep a record of their doses. If they take all their medicine, they get to pick out a small toy from the pharmacy's "treasure chest," he said.
The flavorings aren't just for kids.
Cancer patients have used it to make bad-tasting morphine go down easier, he said.
The flavoring adds $3 to the cost of a prescription.
Haas mixes the flavorings himself, with the help of a recipe chart from the FlavorX company.
He mixes sweetener with different flavors and combines that with the medicine, which comes in powder form, and distilled water. Haas tastes every syrup, just to make sure it's palatable.