WEDNESDAY, Oct. 29, 2025 (HealthDay News) — An anti-inflammation injectable drug can reduce mucus buildup and improve breathing among asthma patients, a new clinical trial says.

The drug dupilumab (Dupixent) effectively clears up airways plugged by mucus during an asthma attack, researchers reported Oct. 27 in the American Journal of Respiratory and Critical Care Medicine.

Results found half as many patients had mucus-plugged airways following treatment with the drug.

“In moderate-to-severe asthma, a buildup of mucus in the lungs can obstruct breathing airways to the point where affected patients suffer limited breathing, severe asthma attacks, and even death,” lead researcher Dr. Celeste Porsbjerg said in a news release. She’s a professor of severe asthma at Bispebjerg Hospital in Copenhagen, Denmark.

Everyone has some mucus in their system, but it typically isn’t bothersome unless we’re stricken with a cold or the flu, researchers noted.

But mucus can be life-threatening to someone with asthma, if inflammation tightens their airway and breathing is cut off by phlegm, researchers said.

“For patients who experience increased mucus production with their asthma flares or attacks, it leads to increased stress/distress and anxiety. Sometimes the stuck mucus can cause gagging because it gets stuck and they can't expel it or cough it out,” De De Gardner, chief research officer for the Allergy & Asthma Network, said in a news release. Gardner was not involved in the study.

Dupilumab originally was approved in 2017 to treat the immune-related disease eczema, and has since been adopted for treatment of other diseases like asthma, sinusitis and COPD, according to Drugs.com.

Dupilumab works by blocking inflammatory proteins in the body. It doesn’t fully suppress the immune system but can calm down its response to illness and infection.

For the new study, researchers randomly assigned more than 100 asthma patients to receive either an injection of either dupilumab or a placebo every two weeks for 24 weeks.

By the end of the study, only 33% of patients on dupilumab had mucus severely plugging their airways compared with 67% at the start.

Placebo patients remained as affected by mucus throughout the study – 77% by the end, 73% at the start.

Analysis of patients’ breath also showed that dupilumab was lowering their inflammation. Patients experienced a significant reduction in exhaled nitric oxide, a marker of inflammation, researchers said.

“In summary, these outcomes show that dupilumab reduces mucus plugging and airway inflammation in patients with moderate-to-severe asthma as early as four weeks after treatment initiation,” researchers concluded in their study.

However, dupilumab isn’t cheap. A month’s supply of two 300 mg injections can cost around $3,900, according to Drugs.com.

Dupilumab’s manufacturer, Sanofi/Regeneron Pharmaceuticals, funded the clinical trial.

More information

Mayo Clinic has more on asthma and mucus.

SOURCES: American Thoracic Society, news release, Oct. 28, 2025; American Journal of Respiratory and Critical Care Medicine, Oct. 27, 2025