A sudden cold snap has driven a spike in holiday clinic visits, with medical professionals urging the public, especially the elderly and those with chronic illnesses, to take the drop in temperatures seriously.

Speaking on an RTHK radio programme on Friday, family doctor Lam Wing-wo warned that the cold poses serious risks like hypothermia, particularly for the vulnerable or those living in poor conditions.

He emphasised the importance of checking on family members to ensure they are keeping warm.

"They may simply feel very tired, but if they don't warm up, it could become life-threatening," he said.

"For citizens with chronic conditions, such as cardiovascular disease, a sudden chill can induce chest pains, potentially triggering acute heart problems.

"Any rise in blood pressure, discomfort, or chest pain should not be ignored. They must see a doctor."

Dr Lam also noted a seasonal rise in flu and cough symptoms.

While the latest figures show a slight dip in flu cases, he cautioned that holiday travel and low humidity still raise the risk of outbreaks.

"Our immune systems are weaker during cold spells," he said.

"Staying indoors with poor ventilation or visiting crowded public places increases exposure.

"When combined with travel to regions experiencing flu outbreaks, the chance of catching flu or other respiratory illnesses rises significantly."

He pointed out that many countries have seen outbreaks recently, and travellers could inadvertently bring infections back to Hong Kong.

"Logically, we should be concerned, but fortunately vaccination rates are improving," he added.

To stay protected, Dr Lam advised reinforcing hygiene practices: frequent handwashing, wearing masks and ensuring good ventilation to reduce cross-infection.

He also recommended avoiding cold drinks and seeking early medical attention at the first sign of flu-like symptoms.