Fever Bark - Guanethidine, Hydrochlorothiazide Interaction
Herbal: Fever Bark
Also Known As: Alstonia constricta, Alstonia Bark, Australian Febrifuge, Australian Fever Bush, Australian Quinine, Bitterbark, Corteza de Alstonia, Devil Tree, Devil's Bit, Dita Bark, Écorce Amère d'Australie, Écorce de Quinquina, Écorce de Quinquina d'Australie
Drug: Guanethidine, Hydrochlorothiazide
Brand names:
Esimil
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
May 25, 2025
Interaction Details
Guanethidine, Hydrochlorothiazide is classified as belonging to the following category: Antihypertensive Drugs
Theoretically, fever bark might alter the effects of antihypertensive drugs.
Yohimbine, a constituent of fever bark, is an alpha-2 adrenoceptor antagonist and has been reported to increase blood pressure in clinical research. Conversely, reserpine can reduce both systolic and diastolic blood pressure. Theoretically, concomitant use of fever bark and antihypertensive drugs can interfere with blood pressure control.
Interaction Rating
Likelihood of Occurrence
ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
References
- Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
- Kearney T, Tu N, Haller C. Adverse drug events associated with yohimbine-containing products: a retrospective review of the California Poison Control System reported cases. Ann Pharmacother 2010;44:1022-9.
- Lobay D. Rauwolfia in the Treatment of Hypertension. Integr Med (Encinitas). 2015 Jun;14(3):40-6.
- Sheldon MB, Kotte JH. Effect of Rauwolfia serpentina and reserpine on the blood pressure in essential hypertension; a long-term double-blind study. Circulation. 1957 Aug;16(2):200-6.
Fever Bark Overview
Fever bark is the bark of the evergreen tree Alstonia constricta. The tree is native to tropical regions of Asia and is known for its tall, straight trunk and glossy, dark green leaves.
Alstonia constricta is used in traditional medicine to treat a variety of ailments, including fever, diarrhea, and infections. The bark of the tree contains several different alkaloids, including reserpine and yohimbine, which could cause serious side effects if misused. Unless you are under the direct supervision of a medical professional, the use of fever bark is not recommended.
Fever bark is sometimes referred to as Australian quinine, but it is not known to contain quinine.
Fever Bark - More Interactions
Fever Bark interacts with 790 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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