Herbal teas are sold in cans in major supermarkets. Provided to China Daily

Liangcha was and still is a very common homemade summer drink in Southern China. The dark brown tisane is usually bitter and sometimes slightly sweet, depending on the combination of herbs used.

The most commonly used are mint, honeysuckle, lotus leaves, perilla, chrysanthemum and Arhat fruit, all of which TCM believes have cooling properties to diffuse internal heat.

Xia, the TCM specialist, says herbal tisanes are very popular in South China, partly because the weather there is hotter and more humid than in the north, although the gap is closing these days.

Different prescriptions of herbs prevent, relieve or cure a variety of summer ailments, such as sore throats, colds and indigestion.

There are many shops selling tisanes in southern cities, such as Guangzhou and Hong Kong.

Up north, the cooling drinks became popular more as soft drinks, and herbal teas are sold in cans, unlike the freshly brewed pots in the south.

Diet is also important to keeping healthy in summer, and a light diet with "cooling" food is best, observes Xie Lijun, a TCM specialist with the No 3 Hospital of Beijing University of Chinese Medicine.

"Food and drink in daily life play an important role in TCM practice," Xie says.

Foods with a cooling nature include cucumbers, beans, mushrooms, pearl barley and watermelons. They are light but rich in vitamins and proteins. They also help the body remove excessive humidity, Xie notes.

It is also eating according to seasons, because most of these vegetables, fruits and melons ripen in summer.

Despite the urge to drink and eat cold food or drink in summer, Xie says it is better to have hot food in summer. Even cooling herbal teas are best drunk while still warm.

Moderation is still the best guide though, as Xia, the specialist with the China-Japan Friendship Hospital, says too much cooling food may cause upset stomachs in people with weak digestions.

A final caution from Xia: Staying in an air-conditioned room for too long may also subject your body to stress. Likewise, being exposed to too much sun is also unhealthy.

The secret is to keep cool and eat healthily.

Li Xiang contributed to the story.