NEW YORK (CBSNewYork) — If you have ever taken a medicine that just didn’t work for you, the problem may be in your genes.

As CBS2’s Dr. Max Gomez explains, a new test could help doctors find the perfect prescription based on your DNA.

“I was given narcotics, which really did not give me any relief from the pain,” said Tony Cirrincione.

Cirrincione always wondered why strong painkillers never eased his kidney stone pain.

Then, he took this pharmacogenomics test at NorthShore. It’s a simple swab of the inside of your mouth.

“Pharmacogenomics is a science of looking at your DNA to understand how you’re going to respond to medications,” said Mark Dunnenberger of NorthShore University Healthsystem.

Depending on how your body processes certain drugs, they may not work for you or may cause side effects.

“We can either avoid those medications or we can dose-adjust up or down,” said Dunnenberger.

Dr. Peter O’Donnell at the University of Chicago has studied more than 1,200 blood samples to learn more about the DNA-drug connection.

“We found that the information covers over 90% of the common U.S. diseases,” said O’Donnell.

Conditions like depression, asthma, arthritis, high cholesterol, high blood pressure, even acid reflux and heartburn, which 29-year-old Shane Tierney has.

“It was very painful,” said Tierney.

He learned that his genes explain why 20 milligram doses of over-the-counter medications weren’t working, which led to a medication switch and a higher dose.

“I’m supposed to take 40 milligrams twice a day,” said Tierney.

Numerous studies validating the gene-drug connection have begun to shape doctors’ everyday practice.

“We saw that it actually changed what they would prescribe,” said O’Donnell.

“We know a relationships to patients’ to genetics and how they might respond to medications for about 20% of the medications available,” said Dunnenberger.

Cirrincione already put his genetic results to good use after a recent arm surgery.

“They prescribed some non-steroidal anti-inflammatory medication… and that worked,” said Cirrincione.

As researchers find more correlations between genetics and drug responses, these tests may eventually become as common as checking your cholesterol levels.

But for now, insurance doesn’t cover the $200 test.