An anesthesiologist is in charge of patient comfort during surgery, providing just the right mix of drugs so the patient doesn’t feel the pain.

"For some patients, one drug is more indicated than others. But for many patients, it's acceptable to choose from any number of either of these classes of drugs,” said anesthesiologist Dr. Brian Freeman.

The drugs are effective but they can cause problems for some patients.

"Anesthetics are great drugs. They make you unconscious so we can perform surgery. But many of them cause an irritation when they're administered to patients and so we wanted to know how they do that," said pharmacologist Gerard Ahern.

Interestingly enough, Georgetown University researchers found certain anesthesia drugs activate the body's “mustard oil” receptor.

"This receptor is expressed in the peripheral nerves, the pain-sensing nerves found throughout the body,” said Ahern.

It's the same pain receptor that reacts when you eat pungent foods like garlic and wasabi, a Japanese horseradish. The finding is the first to scientifically explain the anesthesia side effect and it could lead to new less-irritating drugs.

"We're trying to identify how the anesthetics do activate these pain receptors and maybe tinker with some of the anesthetic molecules themselves to see if we can create ones that don't have this side effect,” said Ahern.

There are anesthesia drugs that do not cause post-surgical pain. They target the central nervous system, not the peripheral nervous system where the mustard oil receptor is located.