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Can I take 5htp and Olanzapine together?

Drug interaction guide

Taking 5-HTP and olanzapine together can lead to a rare but very serious condition called serotonin syndrome. This happens when there is too much of a chemical called serotonin in your brain. Symptoms can include feeling very agitated, confused, or sweaty, as well as having a fast heartbeat, muscle twitching, or shivering. In severe cases, it can be life-threatening.

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Why this happens

Olanzapine is an antipsychotic that affects serotonin levels in the brain. 5-HTP is a supplement that the body uses to produce more serotonin. When used together, they can cause serotonin levels to rise to dangerous levels (additive effect).

Do not take 5-HTP while you are taking olanzapine unless specifically instructed and monitored by your doctor. If you are already taking both and feel unwell, confused, or have a very fast heartbeat, seek medical help immediately. Always tell your doctor about any supplements you are taking alongside your prescription medication.

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Taking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.

Disclaimer

This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.

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Article history

The information on this page is written and peer reviewed by qualified clinicians.

  • 14 Mar 2026 | Originally published
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