Oregano - Benadryl (Diphenhydramine) Interaction
Herbal: Oregano
Also Known As: Origanum vulgare, Carvacrol, European Oregano, Marjolaine Sauvage, Marjolaine Vivace, Mediterranean Oregano, Mountain Mint, Oil of Oregano, Oregano Oil, Organy, Origan, Origan Européen, Origani Vulgaris Herba, Origano, Winter Marjoram, Wintersweet
Drug: Diphenhydramine
Brand names:
Benadryl, Dormin, Allerdryl, Valdrene, Sleep-Ettes D, Simply Sleep, Sominex, Diphenhydramine, Compoz, Sleep Aid, Benadryl cream, Benadryl spray, Dermamycin cream, Ziradryl, Nytol

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Apr 20, 2025
Interaction Details
There were no interactions found between Diphenhydramine and Oregano. This does not mean the potential for an interaction does not exist, however. There is often a lack of studies and data surrounding traditional medicine, especially concerning drug interactions, so it is important to always consult your provider before making any changes to your medication regimen.
Pharmacist Analysis
Oregano (and oregano oil) supplements are generally considered safe and there is no indication that there is an interaction between the drug highlighted in this interaction monograph and oregano.
However, as with all supplements, it is important to talk to your doctor before starting anything new, so you can be appropriately monitored.
In terms of drug interactions that have been reported with oregano, below are some examples.
Anticoagulant; Antiplatelet Drugs
Anticoagulants and antiplatelet drugs work by slowing down or preventing blood clotting. While they are essential medications for individuals with certain conditions, they come with an increased risk of bleeding.
Some studies have reported that oregano oil may also increase the risk of bleeding, as it contains compounds that have antithrombin activity and can inhibit platelet aggregation.
Therefore, taking oregano oil along with anticoagulants or antiplatelet drugs may increase the risk of bleeding, bruising, and other adverse effects.
Anti-Diabetic Drugs
Several studies suggest that oregano supplements may help lower blood glucose (i.e., sugar) levels. In vitro and animal research has shown that oregano extracts might stimulate glucose uptake and reduce blood glucose levels.
Therefore, based on the available evidence, combining oregano oil with antidiabetic drugs could potentially cause blood sugar levels to drop too low, leading to hypoglycemia.
However, it is important to note that studies reporting that oregano can reduce blood glucose levels have not reported it causing hypoglycemia.
References
- Anti-hyperglycaemic activity of the aqueous extract of Origanum vulgare growing wild in Tafilalet region. PubMed
- Inhibitory effect of clonal oregano extracts against porcine pancreatic amylase in vitro. PubMed
- Antithrombin activity of some constituents from Origanum vulgare. PubMed
- Comparative screening of plant essential oils: phenylpropanoid moiety as basic core for antiplatelet activity. PubMed
Oregano With Benadryl
Oregano (and oregano oil) is considered safe to take with Benadryl.
Oregano is not known to affect the metabolism of Benadryl or how it works. Additionally, they do not share a similar side effect profile.
Overall, there is no known interaction between the two.
- Dr. Brian Staiger, PharmDOregano Overview

Diphenhydramine Overview
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Diphenhydramine is used to relieve red, irritated, itchy, watery eyes; sneezing; and runny nose caused by hay fever, allergies, or the common cold. Diphenhydramine is also used to relieve cough caused by minor throat or airway irritation. Diphenhydramine is also used to prevent and treat motion sickness, and to treat insomnia (difficulty falling asleep or staying asleep). Diphenhydramine is also used to control abnormal movements in people who have early stage parkinsonian syndrome (a disorder of the nervous system that causes difficulties with movement, muscle control, and balance) or who are experiencing movement problems as a side effect of a medication.
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Diphenhydramine will relieve the symptoms of these conditions but will not treat the cause of the symptoms or speed recovery. Diphenhydramine should not be used to cause sleepiness in children. Diphenhydramine is in a class of medications called antihistamines. It works by blocking the action of histamine, a substance in the body that causes allergic symptoms.
Oregano - More Interactions
Oregano interacts with 204 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.