A side effect of a drug that was originally used as an immunosuppressant could one day be used to treat baldness.

Researchers have found that the active compound stimulates human hair follicles to grow by targeting a protein that usually puts the breaks on. Publishing their results in the journal Plos Biology, they hope that it can now be developed into a form that could be used to treat alopecia.

“The fact this new agent, which had never even been considered in a hair loss context, promotes human hair growth is exciting because of its translational potential: it could one day make a real difference to people who suffer from hair loss,” said the University of Manchester’s Dr Nathan Hawkshaw, who co-authored the study, in statement.

The drug was actually originally designed to treat transplant patients, to suppress transplant rejection and autoimmune diseases. Known officially as Cyclosporine A (CsA), it has been commonly used since the 1980s, and does, unfortunately, have many side effects. One of the least serious – but most interesting – of these is the fact that it can sometimes cause unwanted hair growth.

The team first set about trying to figure out the molecular mechanism of the drug, before then carrying out a full gene expression analysis of individual human hair follicles, donated by people undergoing hair transplants, which had been treated with CsA. They were able to show that the drug inhibited a particular gene, SFRP1, which has in previous studies been shown to inhibit the growth of tissues, most crucially including hair follicles.

If this could be developed into an effective treatment, then it could have a significant impact on those suffering from hair loss, which for many can cause psychological and mental distress. Currently, treatment is very limited, with patients either having to take one of two drugs – minoxidil and finasteride – or go under the knife and get a hair transplant. While the latter is often quite successful, it is obviously quite invasive, while the two drugs often have mixed results.

The discovery that CsA could potentially offer a fourth solution is exciting. “Clearly though, a clinical trial is required next to tell us whether this drug or similar compounds are both effective and safe in hair loss patients,” Dr Hawkshaw pointed out. But for people who suffer from hair loss, knowing new avenues are opening to explore a remedy will be a relief.