Can 5-Hydroxytryptophan (5HTP) cause gastrointestinal symptoms such as gas, bloating, and weight gain in patients with Mast Cell Activation Syndrome (MCAS)?

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From the Guidelines

Yes, 5-HTP can potentially cause gas, bloating, and weight gain in people with Mast Cell Activation Syndrome (MCAS).

Background

5-HTP is a precursor to serotonin, and while some people take it as a supplement for mood support, it can be problematic for MCAS patients. In MCAS, mast cells inappropriately release inflammatory mediators, and 5-HTP may trigger this release in sensitive individuals.

Gastrointestinal Symptoms

Gastrointestinal symptoms like gas and bloating are common reactions because the gut contains numerous mast cells that can be activated, as seen in the management of irritable bowel syndrome (IBS) where gut-brain neuromodulators are used to treat global symptoms and abdominal pain 1.

Weight Gain

Weight gain might occur due to fluid retention from inflammation or changes in metabolism related to mast cell activation.

Recommendations

If you have MCAS and are considering 5-HTP, start with a very low dose (perhaps 25-50mg) and monitor your symptoms carefully. Many MCAS specialists recommend avoiding supplements that affect neurotransmitters unless specifically prescribed. Instead, focus on a low-histamine diet and MCAS-specific treatments like H1 and H2 antihistamines, mast cell stabilizers, or other medications recommended by your healthcare provider who specializes in MCAS treatment.

Treatment Alternatives

For IBS symptoms, which may be similar to those experienced by MCAS patients, second-line treatments such as tricyclic antidepressants, selective serotonin reuptake inhibitors, and other medications like linaclotide, a guanylate cyclase-C agonist, may be considered, as they have shown efficacy in managing IBS symptoms 1.

From the Research

Mast Cell Activation Syndrome (MCAS) and 5HTP

  • MCAS is a condition characterized by inappropriate mast cell activation, leading to various symptoms, including gastrointestinal issues 2, 3.
  • Gastrointestinal symptoms associated with MCAS include abdominal pain, diarrhea, and nausea, which can be mistaken for functional gastrointestinal disorders 2.
  • There is no direct evidence in the provided studies to suggest that 5HTP causes gas, bloating, and weight gain in individuals with MCAS.
  • However, it is known that individuals with MCAS often experience significant delays in diagnosis and may have refractory symptoms to symptom-targeted prescription medications 2.
  • Management of MCAS typically involves avoiding triggers and modulating mast cell activation and the effects of mediators, which can include simple over-the-counter medications 2.

5HTP and MCAS

  • There is limited research on the specific interaction between 5HTP and MCAS, and the provided studies do not directly address this topic 4, 5, 6.
  • Further research is needed to understand the relationship between 5HTP and MCAS, as well as the underlying mechanisms and pathways that lead to mast cell activation in MCAS patients 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Mast cell activation syndrome: Current understanding and research needs.

The Journal of allergy and clinical immunology, 2024

Research

Clinical Approach to Mast Cell Activation Syndrome: A Practical Overview.

Journal of investigational allergology & clinical immunology, 2021

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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