Serotonin is a monoamine neurotransmitter.
Serotonin may also refer to:
- Serotonin (album), or the title track, by the Mystery Jets, 2010
- Serotonin (novel), by Michel Houellebecq, 2019
- "Serotonin" (song), by Girl in Red, 2021
- Serotonin (wrestling), a professional wrestling stable
- "Serotonin", a 2022 song by Tom Walker
- "Serotonin", a 2009 song by Widescreen Mode