Calamus - Phenergan (Promethazine) Interaction
Herbal: Calamus
Also Known As: Acorus calamus, Acore Calame, Acore Odorant, Acore Olorant, Acore Roseau, Acorus Roseau, Aruna, Bach, Bajai, Baje, Belle-Angélique, Bhutanashini, Cálamo, Calamo Aromatic, Calamus Root, Cinnamon Sedge, Flag Root, Flagroot, Gladdon, Golomi, Grass-Leaf Sweetflag, Grass Myrtle, Ka
Drug: Promethazine
Brand names:
Phenergan
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jun 22, 2025
Interaction Details
Promethazine is classified as belonging to the following category: Anticholinergic Drugs
Theoretically, concurrent use of anticholinergic drugs and calamus might decrease the effectiveness of the anticholinergic drug.
In vitro evidence shows that calamus can inhibit acetylcholinesterase (AChE).
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Oh, M. H., Houghton, P. J., Whang, W. K., and Cho, J. H. Screening of Korean herbal medicines used to improve cognitive function for anti-cholinesterase activity. Phytomedicine 2004;11(6):544-548.
Calamus Overview
Calamus is a grass-like plant commonly mostly commonly found in Eastern Europe in swamps or along the banks of waterways. Calamus has traditionally been used in both Ayurdevic and Chinese medicine for a number of ailments, including digestive disorders including colic, ulcers, gastritis, flatulence, diarrhea, intestinal infections, dyspepsia, and anorexia. It is also used to induce vomiting, induce sweating, improve memory and for the treatment of inflammatory disorders. The FDA does not allow calamus in food due research showing it has carcinogenic effects, likely due to the beta-asarone content, which can vary heavily depending on the species.
Promethazine Overview
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Promethazine is used to relieve the symptoms of allergic reactions such as allergic rhinitis (runny nose and watery eyes caused by allergy to pollen, mold or dust), allergic conjunctivitis (red, watery eyes caused by allergies), allergic skin reactions, and allergic reactions to blood or plasma products. Promethazine is used with other medications to treat anaphylaxis (sudden, severe allergic reactions) and the symptoms of the common cold such as sneezing, cough, and runny nose. Promethazine is also used to relax and sedate patients before and after surgery, during labor, and at other times. Promethazine is also used to prevent and control nausea and vomiting that may occur after surgery, and with other medications to help relieve pain after surgery. Promethazine is also used to prevent and treat motion sickness. Promethazine helps control symptoms, but will not treat the cause of the symptoms or speed recovery. Promethazine is in a class of medications called phenothiazines. It works by blocking the action of a certain natural substance in the body.
Calamus - More Interactions
Calamus interacts with 1091 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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