Can I take 0.2mg and Htp together?
Drug interaction guide
Originally published 14 Mar 2026
Meets Patient’s editorial guidelines
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Taking these two 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 and body. Symptoms can include feeling very agitated, confused, or sweaty, as well as having a fast heartbeat, shivering, muscle twitching, or diarrhoea. In severe cases, it can be life-threatening.
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Why this happens
Both moxonidine (0.2mg) and 5-HTP (hydroxytryptophan) affect chemicals in the brain. While moxonidine is mainly used for blood pressure, it has complex effects on the central nervous system. 5-HTP is converted directly into serotonin. Combining substances that increase serotonin levels or alter brain chemistry in this way raises the risk of 'serotonin overload'.
What you should do
Back to contentsYou should not take 5-HTP with moxonidine unless specifically told to do so 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 or pharmacist about any supplements you are planning to take alongside your prescription medication.
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Using other medicines
Back to contentsTaking 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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