The EU's medicines regulator on Monday advised against using the anti-parasite drug ivermectin for coronavirus outside clinical trials, despite headlines touting it as a miracle cure.

Facebook posts and articles endorsing ivermectin have proliferated in Brazil, France, South Africa, and South Korea as governments around the world struggle with vaccination programmes.

'EMA has reviewed the latest evidence on the use of ivermectin for the prevention and treatment of Covid and concluded that the available data do not support its use for Covid outside well-designed clinical trials,' the European Medicines Agency said.

The Amsterdam-based agency said it had not received any application for authorisation of the drug, which has long been used to treat parasites such as head lice and for river blindness in sub-Saharan Africa.

Further tests were needed to see if it was effective against coronavirus, the EMA said.

Lab tests had found ivermectin could block replication of the virus that causes Covid-19 'but at much higher ivermectin concentrations than those achieved with the currently authorised doses,' the regulator added.

Toxic effects at those higher doses could not be ruled out, it said.

'Results from clinical studies were varied, with some studies showing no benefit and others reporting a potential benefit,' the EMA added.