The Food and Drug Administration (FDA) warned Friday that people should not take chloroquine and hydroxychloroquine to treat COVID-19 outside of a hospital or formal clinical trial, citing reports of “serious heart rhythm problems.” Madeline Farber writes for Fox News that many of those adverse effects occurred in patients with the virus who were treated with the anti-malaria drugs, often in combination with azithromycin, also known as Z-Pak. President Trump has described such drugs as a potential “game-changer,” although results from clinical trials are not yet in to show whether they are effective. “We will continue to investigate risks associated with the use of hydroxychloroquine and chloroquine for COVID-19 and communicate publicly when we have more information,” the FDA wrote. The adverse events reported include abnormal heart rhythms such as QT interval prolongation, dangerously rapid heart rate called ventricular tachycardia and ventricular fibrillation, and in some cases, death, the agency said. The FDA did not say how many deaths have been reported. Patients who also have other health issues such as heart and kidney disease are likely to be at increased risk of these heart problems when receiving these medicines. The malaria drugs are not approved for use in COVID-19 patients, but the FDA is allowing hydroxychloroquine and chloroquine products donated to the Strategic National Stockpile to be distributed and used in limited circumstances, such as for certain hospitalized patients with COVID-19, the agency noted.