What drugs are worth buying in Wanning, Hong Kong?

Hong Kong Wanning and Watsons can buy it.

Mentholatum Leton professional eye drops (yellow bottle, not sold in Chinese mainland)

Relieve eye discomfort caused by using computer, playing games or watching TV, and prevent eye discomfort and itching caused by swimming, dust and sweat.

Lexin Zhenke Ganmao Ling (no sleepy formula)

I think it's good for colds and coughs.

Fishing brand Li Wanshan Stomach Pain, Stomach Strengthening and Whole Intestine Strengthening

It's cheaper than buying in the mainland, because the mainland is also imported from Hong Kong.