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
• "Seratonin", a 2024 song by OneRepublic from Artificial Paradise
• "Serotonin", a 2022 song by Tom Walker

• Serotonin transporter
• Serotonin reuptake inhibitor