Chinese residents are rushing to snap up COVID-19 antigen kits and medicines for fevers and colds as the country's recent easing of prevention measures triggers widespread concern among the public they could now catch the virus.

Online medicine platforms, pharmacies and drug makers have in recent days reported surging sales, with JD Health saying sales of antigen test kits jumped 344 per cent in the week to December 4 compared with the previous week.

A shop assistant at the Tongzhitang Dongdan drug store in downtown Beijing told Reuters they sold out of fever medication on Monday.

"I have never seen so many customers come to buy fever medication in one day," he said.

"We are trying to refill our shelves but it may take a week."

On Monday, the market regulator in Beijing issued a warning against hoarding and hiking prices for epidemic prevention products, including anti-virus drugs, masks and disinfection and sterilisation merchandise.

The surge in demand has driven up share prices in medicine manufacturers, with cough syrup producer Guizhou Bailing and Xinhua Pharmaceutical, which makes 40 per cent of all Ibuprofen sold in China jumping between eight to 10 per cent on Tuesday.

China's strict adherence to its zero-COVID-19 policy during the past three years has kept its general public largely insulated from the waves of infection that whipped around the wider world.

By global standards, China suffered far fewer cases and deaths but the economy paid a price for the tough restrictions on movement.

Authorities finally started to ease some of the toughest restrictions after the public's frustration boiled over late last month with a wave of protests that marked the strongest show of dissent since Chinese President Xi Jinping came to power a decade ago.

While many people are relieved that some requirements have been relaxed - which includes less testing and allowing positive cases to quarantine at home in some places - there are many other people who now feel more vulnerable to catching the virus.

There is also some skepticism over the shift in tone in messaging from officials who had previously emphasised the dangers of the Omicron variant of COVID-19.

China had also in the past three years imposed rules, such as requiring people to register their names to purchase fever and cold medicine to track potential infections but some localities have begun to drop such requirements.

People worried about the potential for catching COVID as the preventative measures are dialled back are also buying Lianhua Qingwen, a traditional Chinese formulation made by Shijiazhuang-based Yiling Pharmaceutical as it has been widely promoted in China for the treatment of COVID-19.

Shandong-based pharmaceutical company Buchang Pharma told local news outlet Cailianshe that its factory making a Chinese medicine for lung disease was working around the clock due to "huge demand".

The rush to stock up on COVID treatments drew scorn in state media.

"There is no scientific basis for irrationally buying and hoarding specific drugs", the Economic Daily wrote on Tuesday.