Treatment with a drug normally used for a bone marrow condition has completely reversed baldness caused by alopecia in three patients, scientists in the US have announced. The sufferers had lost at least a third of the hair on their heads, and each regained total hair regrowth within five months of being treated with ruxolitinib, which is approved in the US and EU for treatment of myelofibrosis.

One of the team from Columbia University Medical Centre, Professor Angela Christiano, has herself suffered from the condition, and described it as: "Not life threatening, but it is life altering".

The results are announced in the online edition of Nature Medicine journal, by the team from Columbia, who previously identified the immune cells responsible for destroying the hair follicles. The treatment would not work for the more common male-pattern baldness, which is linked to hormones.

The scientists tested two FDS-approved drugs known as JAK inhibitors, ruxolitinib and tofacitinib, on mice – where hair loss was completely reversed and the effects proved long lasting – and have now gone on to test ruxolitinib on human patients. Christiano said it was wrong to dismiss the condition as unimportant.

"Nothing could be further from the truth. Patients with alopecia areata are suffering profoundly, and these findings mark a significant step forward for them. The team is fully committed to advancing new therapies for patients with a vast unmet need."

In an interview with the New York Times, Christiano said the condition was first spotted by her hairdresser and then confirmed by a colleague with "a blood-curdling scream". It occurred almost 10 years ago when she had just arrived at Columbia to start her own laboratory, and she was told there was no cure – but in the interview, four years ago, she predicted that treatment could come sooner than expected through "a new indication for an already approved drug".

Of the tiny group of sufferers involved in the clinical trial, all classified as moderate-to-severe, all three showed dramatic hair regrowth after treatment with a twice daily tablet for up to five months. Alopecia areata, which typically causes patchy hair loss, is an autoimmune disease where the immune system attacks and destroys the hair follicles. The team leader, Raphael Clynes, said: "We've only begun testing the drug in patients, but if the drug continues to be successful and safe, it will have a dramatic, positive impact on the lives of people with this disease."

"This disease has been completely understudied – until now, only two small clinical trials evaluating targeted therapies in alopecia areata have been performed, largely because of the lack of mechanistic insight into it."

David Bickers, a practicing dermatologist with many patients with alopecia, said the timeline from genetic findings to positive results in a clinical trial in four years, was astoundingly fast.

"There are few tools in the arsenal for the treatment of alopecia areata that have any demonstrated efficacy. This is a major step forward in improving the standard of care for patients suffering from this devastating disease."