Hong Kong authorities are to restrict sales of laughing gas as part of plans to regulate a number of medical gases by classing them as pharmaceutical products.

The Department of Health on Monday said the Pharmacy and Poisons Board has reviewed regulatory measures regarding medical gases, taking into account how they are dealt with on the mainland and elsewhere.

Under the planned changes, laughing gas, or nitrous oxide, as well as nitric oxide would be regulated as prescription drugs.

Other medical gases, including oxygen, nitrogen, carbon dioxide and helium, would be made over-the-counter medicines.

There would also be registration requirements regarding such gases and manufacturers and wholesalers would have to comply with licensing rules.

Consultations on the proposals will run until January 19.