Old tea: May contain many toxins.

Contaminated tea: Some smells are toxic, such as paint, camphor, etc.

Scorched tea: Tea leaves that have been over-roasted lose their nutrients and taste bad.

Overnight tea: Especially tea that has gone bad, even if the taste hasn’t changed, it is likely to have bred a large number of bacteria. Because tea contains a lot of protein, most of which does not dissolve in hot water and remains in the leaves, when the water temperature is high, the protein on the tea leaves can rot. After being left overnight, a kind of enzyme mold can form, and a large amount of tannic acid remaining in the tea can turn into irritating strong oxides, irritating the stomach and causing inflammation. Therefore, overnight tea should not be drunk.

Over-steeped tea: If tea is steeped for too long, many substances harmful to the body will be extracted.

Cold tea: Tea is better drunk warm. Cold tea can cause coldness and phlegm accumulation.

Hot tea: Tea is usually brewed with high-temperature water, but it should not be drunk when the water is too hot. Overly hot things are extremely harmful to the human digestive tract.