Chinese: Old Wives Tales
I'm not sure we have a saying for "old wives tales".
For the ones that works we call them 偏方 (Folk prescription), others are considered as 流言, 谣言 (rumor), 伪科学 (pseudoscience).

One of such saying is that you cannot wash your hair during menstrual period.
Another is that you cannot eat certain food (e.g., orange and seafood) together, otherwise they'll become toxic.

You can find many of them here. Though it includes not only Chinese stories.