上火 (shànghuǒ, 'rising fire') is the classic TCM concept of having too much internal heat — symptoms include sore throat, mouth ulcers, acne, and constipation.
降火 is the cure: drink
凉茶 (liángchá, cooling herbal tea like Wong Lo Kat
王老吉), eat
苦瓜 (kǔguā, bitter melon), or
绿豆汤 (lǜdòu tāng, mung bean soup). It's everyday cultural common sense across Chinese-speaking communities — even people who reject TCM in general use these terms.
