PARIS (BLOOMBERG) - Hydroxychloroquine, the 65-year-old malaria drug that United States President Donald Trump has praised as a treatment option for coronavirus, appeared not to help patients get rid of the pathogen in a small study.

The pill did not help patients clear the virus better than standard care and was much more likely to cause side effects, according to a study of 150 hospitalised patients by doctors at 16 centres in China. The research, which has not been peer reviewed, was released on Tuesday (April 14).

The drug did help alleviate some clinical symptoms of Covid-19, however, and the patients who took it showed a greater drop in C-reactive protein, a measure of inflammation.

"When testing new treatments, we are looking for signals that show that they might be effective before proceeding to larger studies," said Dr Allen Cheng, an infectious diseases physician and a professor of epidemiology at Melbourne's Monash University.

"This study doesn't show any signal, so it is probably unlikely that it will be of clinical benefit."

There were more side effects in the group of 75 people who took hydroxychloroquine, but they were mostly mild, the most common being diarrhoea.

The researchers, led by Dr Wei Tang of Ruijin Hospital in Shanghai, wrote that the medicine's anti-inflammatory effects probably helped alleviate patients' symptoms.

More studies of hydroxychloroquine are under way after the medicine made headlines in recent weeks and was endorsed by Mr Trump.

"The results of those studies will be of interest," Dr Cheng said.

Related Story India agrees to sell hydroxychloroquine to Malaysia to help fight Covid-19

Related Story Coronavirus explainers: What you should know to protect yourself