"According to the Import and Export Ordinance, painkillers and other pharmaceutical products are under control and require an import and export permit issued by the Department of Health before being taken out of Hong Kong," said Customs Assistant Commissioner (Boundary and Ports) Ida Ng Kit-ching.

"However, it is acceptable if a passenger brings a reasonable amount - like one or two packs - for his/her own use," she added.

With China's announcement this week to drop quarantine for Covid infections from January 8, along with starting to issue passports and visas for citizens to travel overseas, Hong Kong is planning to resume border-crossing travel with the mainland.

Ng said most ports between Hong Kong and the mainland have suspended operations for three years, and Customs is in a series of preparations for border reopening.

"We anticipated more than 800,000 passenger trips will be handled per day at all ports and the airport when the border reopened, the same as the volume in 2019," she said.