While walking along China’s roads, it is not uncommon to see leftover herbs scattered on the surface.

This is not some random dumping problem, it is in fact Traditional Chinese Medicine (TCM) leftovers deliberately poured out by the people who cooked them.

Superstition has it that by pouring the TCM leftovers on public roads, other people can walk and drive over them, thereby helping keep illness at bay.

There is a folk legend that the habit originated in the Tang dynasty (618–907).

Sun Simiao, who was hailed as China’s King of Medicine, lived away from the court and was keen on treating ordinary people.

He was said to have passed by a village one time and saw an elderly man pouring leftover TCM ingredients he had cooked outside his door.

Sun was curious at the rare action and checked with the man.

The man told Sun that he had consumed more than 10 doses of medicine, but his condition had not improved.

Sun took the man’s pulse, examined the leftovers and realised that the man had used the wrong medicine.

Sun prescribed him something new, which successfully cured him.

It was believed that this incident initiated a trend of pouring TCM leftovers on the roads, as people all wanted brilliant doctors to check their medicine.

Another belief is that some people poured the leftovers out in public for other poor people to pick them up for use.

Today, people often apply TCM leftovers to the skin or make a foot bath.

The most widely believed theory is that some people do it onto roads in the belief others will see off their illness by treading on the herb residue.

The action is also suggestive of curing, as there is a Chinese idiom that goes yao dao bing chu, which means “The disease is cured the moment the medicine is taken”.

Dao, which means “taken” here, is homophonic to another character that means “pouring”.

A person from eastern China’s Zhejiang province said on social media that when he was young, his neighbours all sneaked out in the night to pour away the TCM leftovers they cooked, hoping that passers-by would collectively kill the disease the next day.

He added that nowadays, when many TCM clinics offer herbal remedies decoction service, many people would not even have access to the dregs of the concoction made for them.

While some older generations are more used to cooking TCM herbs at home and still carry on the superstitious tradition, some people spread the knowledge online to warn people to avoid walking on TCM leftovers.

“If they really believe the magic of pouring out the TCM leftovers, are those people not harming others by doing so?” said one online observer.

“I believe doing good deeds is more helpful in treating illnesses than pouring medicine leftovers on the road,” said another.

A third person asked: “Does throwing the packaging of Western medicine on the road have the same effect?”