头疼 literally means 'head pain' — 头 (tóu) means 'head', and 疼 (téng) means 'to hurt' or 'painful'. Together, they form a common compound word meaning 'headache' as a noun, or 'to have a headache' as a verb. It’s used in both formal and informal contexts, especially in everyday health-related conversation. Unlike more clinical terms like 偏头痛 (piān tóu tòng, 'migraine'), 头疼 is general and neutral, covering mild to moderate head discomfort.

This word frequently appears in sentences describing physical symptoms, making plans ('I can’t go out — I have a headache'), or expressing sympathy ('You look tired — do you have a headache?'). It can stand alone as a subject ('头疼很常见') or follow subject pronouns with no additional verb ('我头疼'). While it may occasionally be used figuratively (e.g., metaphorically for a 'pain in the neck'), such usage is rare and context-dependent — learners should treat it primarily as a literal health term.