A low-cost, widely used anti-inflammatory drug improved survival in patients with COVID-19, the first treatment to show lifesaving promise months into the pandemic.

Deaths among patients who needed breathing assistance were lower over a period of four weeks when they received the 60-year-old medicine dexamethasone, University of Oxford researchers said Tuesday. The study was stopped early because of its crucial findings.

There was no benefit among patients who didn’t need breathing support.

Doctors and companies are scouring for treatments that can help patients survive the new coronavirus, which has killed more than 430,000 people worldwide. Gilead Sciences’ antiviral remdesivir, which has approval to treat COVID-19, has demonstrated only the ability to shorten patients’ recovery.

Dexamethasone treatment reduced deaths by a third among patients on ventilators and by a fifth among those receiving oxygen only, the study showed.

The steroid medicine has been available as a generic for decades and costs $6 or less for a course of treatment, health officials said. Made by pharmaceutical companies including Mylan and Merck, it’s used to treat a range of ailments including rheumatism, asthma, allergies and even to help cancer patients better handle the nausea triggered by chemotherapy.

The dexamethasone research was part of a larger study, called Recovery, that compares a number of potential treatments in an attempt to identify quickly those that are most effective. More than 11,500 patients have been enrolled from more than 175 National Health Service hospitals across the U.K.

A number of anti-inflammatories are being studied around the world for helping coronavirus patients cope with a powerful overreaction of the immune system, sometimes called a cytokine storm.

“While this study suggests dexamethasone only benefits severe cases, countless lives will be saved globally,” said Nick Cammack, COVID-19 therapeutics accelerator lead at Wellcome, the medical research philanthropy group.

The need for new treatments has been exacerbated as the U.S. Food and Drug Administration revoked emergency-use authorization for two malaria drugs touted by President Donald Trump as COVID-19 treatments this week after determining they were unlikely to work against the virus and could have dangerous side effects. The medications may also interfere with the effectiveness of Gilead’s remdesivir, the agency warned.