Hydroxychloroquine and chloroquine didn’t benefit patients with the coronavirus, either alone or in combination with an antibiotic, according to the study published Friday by The Lancet medical journal.

Researchers are searching through available options to treat the coronavirus, which has killed more than 330,000 people, including drugs like the antimalarials that are also already approved to treat lupus and rheumatoid arthritis. Trump’s endorsement has led many people to take the medications without scientific proof of their benefit.

The study looked at the records of 15,000 people who had been treated with the antimalarials and one of two antibiotics that have sometimes been paired with them. Treatment with any combination of the four drugs was associated with a higher risk of death than seen in 81,000 patients who didn’t receive them.

The drugs should only be used for COVID treatment as part of robust studies that will definitively show their impact, the researchers said.

Only one drug, Gilead Sciences Inc.’s remdesivir, has been shown to benefit coronavirus patients in a clinical trial. It reduced patients’ recovery time from an average of 15 days to 11 days in that study.

Trump said this week that he’s taking hydroxychloroquine in an effort to ward off the coronavirus.