Theanine - Granisetron Interaction
Herbal: Theanine
Drug: Granisetron
Brand names:
Kytril, Sustol
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Feb 13, 2023
Interaction Details
Granisetron is classified as belonging to the following category: Serotonergic Drugs
Clinical studies regarding the effects of L-theanine on serotonin levels are conflicting. Some studies suggest it can increase serotonin levels in the brain while others report that it may decrease them. Nevertheless, there have been no reports of l-theanine being a causative agent in serotonergic-related side effects or serotonin syndrome.
Interaction Rating
Likelihood of Occurrence
UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Pharmacist Analysis
Studies suggest that L-theanine may act as a GABA agonist and increase GABA levels in the brain, leading to relaxation, and potentially influencing changes in levels of dopamine and serotonin. However, animal studies report that L-theanine has been shown to decrease serotonin concentrations in the brain and may enhance the degradation of serotonin.
Overall, there isn't consistent evidence to make a reliable determination on how L-theanine could affect serotonin levels overall. Regardless, there are no case reports or clinical studies showing it carries a risk of causing serotonin-related side effects and studies have even utilized it for those taking antidepressants with no reported adverse reactions.
Resources
- Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis. Nutr Rev . 2014 Aug;72(8):507-22
- Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study. Acta Neuropsychiatr . 2017 Apr;29(2):72-79
- Theanine-induced reduction of brain serotonin concentration in rats. Biosci Biotechnol Biochem . 1998 Apr;62(4):816-7
Theanine Overview
Theanine, often referred to as L-theanine as that is the predominant isomer of theanine, is an amino acid commonly found in tea leaves, particularly in green tea. It is purported to increase levels of GABA, serotonin, and dopamine in the brain, which can help to reduce stress and anxiety. L-theanine may also promote a sense of calm and improve overall well-being. Some studies have also suggested that it may improve cognitive function, although more research is needed. Most reported drug interactions with theanine are due to its sedative effects.
Granisetron Overview
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Granisetron is used to prevent nausea and vomiting caused by cancer chemotherapy and radiation therapy. Granisetron is in a class of medications called 5-HT3 receptor antagonists. It works by blocking serotonin, a natural substance in the body that causes nausea and vomiting.
Theanine - More Interactions
Theanine interacts with 557 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
| Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
| Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
| Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
| Unknown | No interactions have been reported or no interaction data is currently available. |
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Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Drug descriptions are provided by MedlinePlus.
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Dr. Brian Staiger, PharmD
In addition to being a clinical pharmacist specializing in pharmacotherapy, Dr. Brian Staiger is a registered herbalist through the American Herbalist Guild. He has combined his passion for pharmacy practice with the study of medical ethnobotany to improve patient care. Feel free to reach out about any of your herbal or medication questions!
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