Essential Oils and Medicines: What Is Known About Interactions
What is known about essential oils and medicines, from wintergreen and warfarin reports to peppermint and lavender studies, and where proper evidence was not found.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
Tell your pharmacist or prescriber about any essential oil product you use, and tell your surgical team before a procedure. NCCIH says lavender might interact with some sedative drugs or herbs, which matters before surgery. [1] Do not stop or change a prescribed medicine yourself.
The question
Can an essential oil change how a medicine works? For most oils and most ways of use, Proper evidence not found: we searched PubMed for aromatherapy and essential oil drug interactions and for inhaled and topical use, and found few human studies. Poison Control states only that essential oils may also interact with medications. [2] The findings below are specific to the oil, the form and the study.What was found
| Oil or product | What the source found | Form and population | Label |
|---|---|---|---|
| Wintergreen oil (methyl salicylate) and warfarin | 11 patients on warfarin had raised INR after heavy use of a methyl salicylate ointment; 3 had bleeding signs [3]. A case report describes an INR of 12.2 after daily use of a pain gel on the knees for eight days [4] | Topical products, case reports | Reported in humans, small numbers |
| Wintergreen oil, general | A review says methyl salicylate (oil of wintergreen) is in many liniments, ointments and medicated oils and that excessive use with warfarin may result in bleeding [5] | Review | Reported |
| Peppermint oil and a blood pressure medicine (felodipine) | In 12 healthy volunteers, peppermint oil (600 mg) was followed by total felodipine exposure (area under the curve) of about 140% of that with water. The authors said the mechanism needs further investigation [6] | Oral peppermint oil, one study | Promising but limited (small human study) |
| Lavender oil capsules (silexan) | In 16 healthy volunteers, repeated 160 mg a day had no clinically relevant effect on five liver enzymes [7] | Oral capsule product only | Single small study |
| Lavender and sedatives | NCCIH says there are theoretical reasons to suspect interactions with sedative drugs or herbs [1] | Not shown in people | Theoretical |
| Oils and medicated creams | A review says essential oils can enhance penetration of drugs from topical formulations [8] | Review of formulation research | Preclinical or formulation research |
How to read this
- Amounts in the table are trial amounts, not advice. The peppermint and lavender results are about tested products. They do not tell you about inhaling the scent, rubbing an oil on the skin or any other oil.
- A normal result for lavender capsules does not clear lavender in other forms. We do not apply it to other oils.
- The warfarin findings are about methyl salicylate products. We did not find a source we read reporting the same for other essential oils.
- NCCIH advises talking with your health care provider before using any herbal product if you take any medicine. [9]
- The skin-penetration review is about drug-delivery research. We did not find a source showing it happening with home use, so treat it as theoretical for readers.
Groups to ask about
We found no source we read that lists medicine groups for inhaled oils. For wintergreen, the source group is blood thinners such as warfarin. [5] For lavender, sedatives. [1] For peppermint oil taken by mouth in trials, a calcium channel blocker was studied. [6] See Supplements and Blood Thinners and Interactions by Drug Class.Before surgery
NCCIH names an upcoming surgical procedure as a reason to ask about lavender and sedatives. [1] Tell the surgical team about any oil, rub or capsule. See Supplements Before Surgery.Other people to ask about
Pregnancy, children, liver and kidney conditions and seizure disorders are covered on their own pages: Essential Oils in Pregnancy and Breastfeeding and Essential Oils, the Liver and Kidneys and Medicine Cautions.How interactions are described
See How Interactions Work for documented, reported, preliminary and theoretical risks. Individual oils: Wintergreen Oil, Peppermint Oil and Lavender Oil.Frequently asked questions
Do essential oils interact with medicines?
Sometimes, for specific oils and forms. Examples are wintergreen products with warfarin [3] and, in one small study, oral peppermint oil with felodipine. [6] For most oils, proper evidence not found.
Is wintergreen oil safe with warfarin?
Reports describe raised INR and some bleeding with methyl salicylate ointment. [3] Ask the prescriber or pharmacist.
Can lavender affect sedatives?
NCCIH says there are theoretical reasons to suspect it. [1] It was not shown in people in the sources we read.
Does inhaling oils affect medicines?
Proper evidence not found. We searched PubMed and found no usable human study of drug interactions with inhaled oils.
Who should I ask?
A pharmacist or prescriber. See Questions to Ask Your Pharmacist.
References
- National Center for Complementary and Integrative Health (NCCIH). Lavender: Usefulness and Safety. Read 2026-10-22.
- Poison Control (poison.org). Essential oils: Poisonous when misused. Reviewed by clinical toxicologist and pharmacist authors; no date shown on page. Read 2026-10-22.
- Yip AS, Chow WH, Tai YT, Cheung KL. Adverse effect of topical methylsalicylate ointment on warfarin anticoagulation: an unrecognized potential hazard. Postgrad Med J. 1990 (11 patients). Read 2026-10-22.
- Joss JD, LeBlond RF. Potentiation of warfarin anticoagulation associated with topical methyl salicylate. Ann Pharmacother. 2000 (case report). Read 2026-10-22.
- Chan TY. Potential dangers from topical preparations containing methyl salicylate. Hum Exp Toxicol. 1996 (review). Read 2026-10-22.
- Dresser GK, Wacher V, Wong S, Wong HT, Bailey DG. Evaluation of peppermint oil and ascorbyl palmitate as inhibitors of cytochrome P4503A4 activity in vitro and in vivo. Clin Pharmacol Ther. 2002 (laboratory study and 12-volunteer crossover study). Read 2026-10-22.
- Doroshyenko O, et al. Drug cocktail interaction study on the effect of the orally administered lavender oil preparation silexan on cytochrome P450 enzymes in healthy volunteers. Drug Metab Dispos. 2013 (16 volunteers). Read 2026-10-22.
- Herman A, Herman AP. Essential oils and their constituents as skin penetration enhancer for transdermal drug delivery: a review. J Pharm Pharmacol. 2015 (review). Read 2026-10-22.
- National Center for Complementary and Integrative Health (NCCIH). Peppermint Oil: Usefulness and Safety. Read 2026-10-22.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.