This disease strips pigment from their skin. Now, a new drug could help restore vitiligo patients’ skin color.

But when her teenaged daughter came home from school sobbing two years ago, saying she didn’t want to end up like her mother — white patches were already starting around the teen’s eyes — Birleanu was determined to find an easier path for her children. She discovered a study at Tufts Medical Center testing a new cream to treat vitiligo and was the first volunteer to sign up.

Based on the results from that study, the Food and Drug Administration Monday green-lighted the medication, known as ruxolitinib. It is now the first federally approved, at-home treatment for repigmentation in patients with vitiligo.

“It’s one thing to deal with this for yourself, but you don’t want it for your kids,” said Birleanu, a 48-year-old North Andover mother of two daughters.

Medical experts estimate that up to 2 percent of the population has vitiligo, which causes a person’s immune system to mistakenly attack the cells that produce pigment, known as melanin, leading to patches of white skin that usually spread over time.

Vitiligo is not contagious or life-threatening. But it can be life-changing.

“I was a shy girl and this just kind of pulled me back,” Birleanu said. “It doesn’t hurt on the outside but it does hurt very much on the inside.”

Results from that trial have not yet been published, but preliminary data show that about 30 percent of participants experienced a 75 percent restoration of pigment on their faces after using the cream twice a day for six months. By one year, that grew to roughly half of the participants.

Also at the one year mark, roughly half of the patients saw a 50 percent improvement in pigmentation on their bodies.

“Some people respond very early and quickly, while other people take longer, and some people don’t respond at all, and we don’t know why yet,” said Dr. David Rosmarin, vice chair of research and education in dermatology at Tufts Medical Center, and lead investigator in the trial.

The study was funded by Incyte Corp., the company that manufactures the new medication, sold under the brand name Opzelura, and was granted the FDA approval.

One vexing problem with other vitiligo treatments, which include anti-inflammatory and steroid medications and ultra violet light sessions, is that when halted, up to 40 percent of patients relapse within the first year.

What happens when patients stop using ruxolitinib cream is an open question, Rosmarin said.

“We don’t have a great answer for that yet. It may be that people need to use this twice a week for maintenance,” he said.

Rosmarin is continuing to study that concern.

Side effects reported from the study include mild acne in about 6 percent of the participants, and a similar percentage reported red or itchy skin.

But federal regulators required Incyte to include a warning label for its ruxolitinib cream because it is in a class of drugs known as a Janus kinase (JAK) inhibitors, that have been shown to cause serious infections and cardiovascular problems in patients given the drug orally for other conditions.

The FDA first approved Incyte’s cream last fall to treat eczema, a chronic condition that makes skin red and itchy. Since then, some doctors have prescribed the cream “off label” for vitiligo. By approving the medication for vitiligo as well, it makes physicians more likely to prescribe it, and insurance companies to cover the costs, which can be significant for patients without such coverage.

“This really fills a gap that existed for our vitiligo patients,” said Dr. Nicole Gunasekera, director of the vitiligo clinic at Brigham and Women’s Hospital.

She said the handful of vitiligo patients to whom she prescribed the cream since last fall had to go to a compounding pharmacy that made it specially for them at a cost of about $400 per tube.

The FDA approved the cream for use by patients 12 years and older, across 10 percent of their body. Doctors say one tube of the cream would last about one month for patients using it across 4 percent of their body, an area the size of about four palms.

While some patients choose not to treat their vitiligo, saying their white patches are now part of their identity, others have eagerly awaited approval of the cream.

That includes 12-year-old Aliya Sawyer of Dracut, who programmed an alert into her cellphone for this week to remind her mother the FDA approval was likely coming and she needed to make an appointment with a dermatologist to get a prescription.

“I haven’t done treatments for a long time because last time I felt like I was a lab rat,” said Sawyer, who was first diagnosed at 5 years old.

She endured ultraviolet light therapy sessions three times a week for several months when she was 5, but the vitiligo progressed faster than the treatments. By first grade, large patches of white covered her formerly caramel-colored skin and she gave up on the treatments.

In summer, some of her pigment typically returns as she spends time outside in the sun. And then her skin gets more mottled deeper into the fall, a relentless cycle that has prompted bullying.

“One person said to me, ‘I think you would be much prettier if you didn’t have vitiligo,’” said Sawyer, who has become a beacon for many children with the disease, speaking at conferences and offering support.

A year ago, Sawyer had lost 90 percent of her pigment, but with more of her color returning this summer than ever before, she is hopeful the new cream may prove the tipping point for her.

For Adriana Birleanu, the North Andover mother who enrolled in the trial to help find a better treatment for her daughter, the new cream has made a significant difference. The white patches are nearly gone from her face and elbow, and are easily covered with make up.

But she has yet to see improvement on her hands and feet.

“It’s not like cancer I know, it’s not like something that hurts, but it’s something that I have had to accept, and it’s hard some days even after all these years,” she said. “My hope [with this medication] is for the kids, the boys and girls out there, that they don’t have to go through this.”

Kay Lazar can be reached at kay.lazar@globe.com Follow her @GlobeKayLazar.