WASHINGTON HEIGHTS, Manhattan –– More than four billion prescriptions a year are filled in pharmacies in the U.S. — but others are filled illegally in delis or bodegas, stashed under a counter, traded for cash.

With undercover cameras rolling, PIX11 bought antibiotics at different delis, no doctor's prescription necessary, simply by telling a clerk about a sore throat and asking for something for pain.

These cashiers were happy to reach into their under-the-counter stash and dole out dubious meds. And when PIX11 confronted them with these underground deals – one clerk said he did it because it made people happy.

And when PIX11 asked about this bootleg buying, even though out in the open, every agency that handles illegal drugs admits there are no investigations. From the NYPD, the city or state, Department of Health, the DEA or FDA.

"The misuse and overuse of antibiotics is contributing to what really is an epidemic of antibiotic resistance, " Dr. Lisa Saiman of Columbia Medical.

Saiman is a fighter on the front lines of combatting disease-resistant antibiotics. She says this is a huge problem, with life and death ramifications.

"We're running out of antibiotics and it's very difficult to make new antibiotics that will actually kill these superbugs," Saiman said. "It's what keeps me awake at night."

PIX11 showed our illegal antibiotics, labeled "Ampicillin" from the Dominican Republic, to Dr. Saiman and a pharmacist.

Both say properly prescribed, it's a well used antibiotic used worldwide.

"Antibiotics should only be taken when prescribed by a doctor for infections they work for," Saiman said. "I have no idea how this is manufactured. I truly worry."

The bodega workers each said they bought them form someone who came in off the street and according to both a pharmacist and Dr. Saiman, none of the dosing advices they gave us was close to correct.

"You could end up sicker," pharmacist Ratha said. "Or in the hospital, because of an allergic reaction."