NEW YORK (CBSNewYork) — More than 25-million Americans have asthma — a number that keeps on climbing.

While many are controlled with medication, about half of all asthmatics still have an attack in a given year.

READ MORE: New York Weather: CBS2's 7/31 Saturday Morning Forecast

Now, there is something cheap and over the counter that could be as good as an inhaler.

High school freshman Isabel Muschweck will never forget her first asthma attack.

“I was at a dance, and after a while I couldn’t breathe. And my friend also started noticing too, that I wasn’t able to breathe, and I started crying. It was like one of the most scariest things for me because I had no idea what was going on,” Mushweck told CBS2’s Dr. Max Gomez.

Even with inhalers and breathing treatments, Isabel suffered two to four asthma attacks a year.

“The attacks she has had were horrifying, and immediate. And when your child cannot breathe, it’s the most helpless thing you feel in the world,” Susan Mushweck said.

Now, she’s taking part in a study to see if Vitamin D might help.

READ MORE: New York City Rolls Out $100 Incentive For Getting Vaccinated As CDC Report Warns Delta Variant As Contagious As Chicken Pox

Other studies have shown a relationship between asthma and low Vitamin D levels.

Well controlled asthma patients with low Vitamin D levels will get either Vitamin D or a placebo. They’ll be carefully tracked for a year.

“At the end we’ll see whether the kids receiving Vitamin D had a lower rate of asthma attacks than the kids who received placebo,” Dr. Juan Celedon, Lung and Allergy Specialist, UPMC Children’s Hospital of Pittsburgh, said, “We can also check whether the children who were on Vitamin D are able to reduce their dose of medication more often than those who are on placebo.”

It will take four years to enroll enough patients to get the final results.

“Vitamin D is very inexpensive, and asthma attacks are such a huge problem that even if we make a small difference, that could have a very big impact,” Dr. Celedon said.

Other studies have shown that many Americans are Vitamin D deficient, partly because of widespread sunscreen use — to prevent skin cancer — which also keeps the skin from making natural Vitamin D.

That might be part of the explanation for the increase in asthma in recent years.

MORE NEWS: Broadway Vaccine Mandate: Audiences Must Be Vaccinated And Masked; Performers, Crew And Staff Required To Be Vaccinated