pejorative language - Single word to describe someone who is overly sensitive

Consider nervous ("Easily agitated or alarmed" and "Apprehensive, anxious, hesitant, worried"), or in the UK, nervy ("Feeling nervous, anxious or agitated"). Also excitable, edgy ("nervous, apprehensive"), uptight, jumpy, sensitive, fragile, delicate.

Edit: Neurotic, typically negative in connotation, is used informally to mean "overly anxious".