‘头痛’ literally means 'head pain' — it combines 头 (tóu), meaning 'head', and 痛 (tòng), meaning 'pain' or 'ache'. It is the standard, neutral term for 'headache' in Mandarin and is used across all registers, from casual conversation to medical contexts. Unlike some English expressions that use metaphors (e.g., 'brain fog'), 头痛 refers specifically to physical discomfort in the head region, including tension headaches, migraines, or pain caused by colds or fatigue.

This noun functions as a subject, object, or predicate in sentences and does not require additional particles to indicate possession or state. It commonly appears with verbs like 有 (yǒu, 'to have'), 感到 (gǎn dào, 'to feel'), or 缓解 (huǎn jiě, 'to relieve'). While it can be modified by adjectives like 严重 (yán zhòng, 'severe') or 轻微 (qīng wēi, 'mild'), it is rarely used attributively before another noun without structural support (e.g., you wouldn’t say *头痛药 without the measure word or particle).