File: The medicine has been touted by US President Donald Trump, who has said he used it as a prophylaxis against the novel coronavirus.
PARIS - Anti-malarial drugs chloroquine and hydroxychloroquine should only be used to treat COVID-19 in clinical trials or in case of "national emergency", the European Medicine Agency warned.
Around the world, countries are expanding access to the two compounds, which are used to treat malaria and are known to have anti-viral properties.
The medicines have shown early promise against the COVID-19 illness in early studies in France and China.
But the EMA cautioned that the drugs should not be used to treat COVID-19 cases unless absolutely necessary.
"It is very important that patients and healthcare professionals only use chloroquine and hydroxychloroquine for their authorised uses or as part of clinical trials or national emergency-use programmes for the treatment of COVID-19," it said.
Both drugs have a number of potentially serious side effects, especially when taken in high doses or administered in tandem with other medications.
"They must not be used without a prescription and without supervision by a doctor; prescriptions should not be given outside their authorised uses except in the setting of a clinical trial or nationally agreed protocols," the EMA said in a statement.
There are also fears of shortages particularly of chloroquine, the less risky of the two medicines that is also used to treat arthritis.
Several countries are conducting clinical trials for the drugs as part of their campaigns to quell the COVID-19 pandemic.