A drug commonly used to treat asthma attacks is in short supply, increasing anxiety for patients who use it—and for pharmacies and health care facilities that provide it.

Albuterol sulfate inhalation solution has been in short supply since last fall, according to the U.S. Food and Drug Administration. A major manufacturer, Akorn, shut down in February, throwing a major wrench in the supply chain, according to the American Society of Health-System Pharmacists, which tracks drug shortages.

Albuterol is a bronchodilator that provides relief from asthma attacks by relaxing smooth muscles in the airways. But it’s also used to treat patients with respiratory illnesses like RSV, and chronic respiratory conditions like chronic obstructive pulmonary disease or COPD sometimes referred to as emphysema, Carl Hinkson, president of the American Association for Respiratory Care, tells Fortune.

Just who is affected? If you’ve been prescribed albuterol and haven’t been impacted yet, will you be in the future? Here’s what patients with respiratory disease need to know about the shortage of the life-saving drug.

Inhalers aren’t in short supply

The shortage is only of the liquid form, used in nebulizers. At the moment, albuterol inhalers aren’t in short supply and may never be.

It’s good news for adults with more mild disease who only use an inhaler. It’s not so good news for patients on nebulizers, who tend to have more severe disease. Nebulizers are often a better choice for such people because they seem to deliver medication more deeply into the lungs, Dr. John Schumann, executive medical director of Oak Street Health, a chain of primary care clinics that serve older adults. He sees patients in Tulsa, Okla.

Regardless of disease severity, nebulizers are also often prescribed for children, who have a hard time following directions to properly use an inhaler, experts tell Fortune. They’re also frequently used in health care facilities like hospitals due to the severity of cases seen there.

A similar drug can be prescribed

Thankfully, when it comes to albuterol, “there’s a good alternative available,” Schumann says: levalbuterol. It’s just as effective in treating moderate asthma, with no difference in side effects, according to a 2008 article in American Family Physician. And there’s currently no shortage of it. A shortage could occur, however, if demand increases.

Not all areas, or patients, are affected by the current shortage

So far, Schumann hasn’t seen any patients affected. And none of the hospitals Hinkson’s organization works with have been impacted yet. He does know, however, of some pediatric hospitals that have shifted to using levalbuterol for kids on nebulizers. The shortage could worsen, however, if those who use the drug attempt to sock up en masse.

It’s even more important now to be vigilant about your lung health

Patients should always seek to avoid triggers, but it’s even more crucial right now, Hinkson says. Triggers vary by person but can include illness, cold, and smoke. To maintain general lung health, the American Lung Association recommends quitting smoking, if you’re a smoker; taking steps to improve your indoor air quality; avoiding outdoor air pollution; and visiting your doctor for regular check-ups.

If you’re concerned you might be impacted by the albuterol shortage, contact someone on your health care team

This could be your pharmacist, who can see if you might be affected the next time you fill your prescription and contact your doctor for a different prescription, if so, Hinkson says. You could also contact your prescribing doctor.