A drug that created the odd side effect of unwanted full body hair growth may hold the key to a new way to treat male baldness.

Researchers from the University of Manchester think they have found a way to harness this odd side effect to coax dormant hair follicles to grow again.

In a new report in the journal PLOS Biology, the researchers said they began their study by looking at an old immunosuppressive drug, Cyclosporine A (CsA), which is used to treat autoimmune diseases and suppress organ rejection after transplants.

The drug has many known side effects, including unwanted hair growth. After studying how the drug affects hair follicles, the team realized CsA reduces the expression of a protein that inhibits the growth of many tissues, including hair follicles.

The team says that after “some detective work,” they found another drug that targets the same protein – but one that carries much fewer side effects.

That drug was is WAY-316606, a compound originally developed to treat osteoporosis. They tested the compound on human hair follicles grown in a lab, and found that it effectively enhanced hair growth.

The team says if the drug can be applied externally, directly to a balding human scalp, it could “wake up” resting hair follicles and cause them to begin to grow again, without risking the side effects of taking the drug internally.

Though many are touting the new discovery as a “cure” for baldness, others are less optimistic, including Dr. Robert Jones, a surgeon in the Toronto area who specializes in hair transplants.

“I don’t think this is ever going to be a hair loss cure because the real culprit with hair loss is DHT (dihydrotestosterone)… a byproduct of testosterone,” he told CTV’s Your Morning Friday.

Dr. Jones explained that some men are simply doomed to develop baldness, technically known as “androgenetic alopecia.”

“If you have a genetic predisposition to male pattern baldness… you’ll have DHT receptors in those follicles. So as soon as those become active, those hairs will cease to exist,” Dr. Jones said.

There are currently two medications to treat baldness – finasteride and minoxidil –which are effective in about 80 per cent of men. But both often produce disappointing regrowth and have side effects that can include impotence. As well, once the medications are stopped, hair loss begins again.

Dr. Jones said while this new experimental drug might waken dormant hair follicles, to call it a potential hair loss cure is “a bit premature,” he said, particularly since the drug has not yet been tested on humans.

“I think it will be just one more tool that physicians will have. Right now, there’s Propecia (finasteride), there’s Rogaine (minoxidil), and this will be one more tool that will bring those hairs out of a resting phase to an active phase,” he said.