Herb & supplement monograph

Oak Moss Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by ·Updated July 2026
What is this page for?

First and foremost: how Oak Moss interacts with medications. The heart of this page is the interaction list — every drug Oak Moss is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Oak Moss is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Interaction report

Drugs that interact with Oak Moss

0 medications have a known interaction with Oak Moss, graded by severity. Select any drug for the full evidence-based detail.

We don’t currently list any known drug interactions for Oak Moss. This doesn’t guarantee none exist — always confirm with your pharmacist before combining supplements with your medications.

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction 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.
  • Possible. Interaction 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
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact Oak Moss combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
Monograph

Oak Moss: Uses, Safety & Side Effects

Medically reviewed by · Reviewed July 2026 ·
The bottom line

Oak moss is a lichen that grows on oak and other trees and is best known as a perfume ingredient prized for its earthy, woody scent. There is very little human evidence to support taking it for any health condition, and it is a well-known skin allergen, so it is mainly used externally in fragrances rather than as a dietary supplement.

Oak Moss
Scientific name
Evernia prunastri
Family
Parmeliaceae
Part used
Whole lichen (thallus) and its extract/absolute
Common forms
Essential oil, absolute, extract, fragrance ingredient; occasionally tinctures
People commonly use it for
  • Perfume base note and scent fixative
  • Aromatherapy and fragrance
  • Traditional antimicrobial use
  • Soaps and cosmetics fragrance

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallUse caution

Oak moss is a recognized skin allergen and is not well studied as an oral supplement.

PregnancyPossibly Unsafe

When used orally. The constituent thujone shows evidence of uterine stimulant activity.

Read the full pregnancy detail
BreastfeedingPossibly Unsafe

When used orally. The constituent thujone shows evidence of uterine stimulant activity.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Oak moss is not actually a moss. It is a type of lichen, which is a combination of a fungus and an alga living together. It grows on the bark and branches of oak trees and sometimes other trees, mostly in forests and woodlands across Europe, North America, and other temperate regions.

Oak moss is most famous in the perfume world. Its extract has a deep, earthy, woody smell and helps fragrances last longer on the skin. You will find it as a base note in many colognes, perfumes, soaps, and cosmetics.

Although it has a long history in traditional practices, oak moss is rarely used today as a dietary supplement. Most modern use is external, in fragrance and skin-care products.

How it works

Oak moss contains natural compounds such as atranorin, evernic acid, and other lichen acids. These substances are responsible for much of its scent and have shown some activity in laboratory studies.

In test-tube research, certain lichen compounds appear to slow the growth of some bacteria and fungi and may act as antioxidants. However, these are early, preliminary findings. We do not have good evidence that swallowing or applying oak moss produces meaningful effects in people.

Some of these same compounds, including atranorin and chloroatranorin, are also the main reasons oak moss can cause allergic skin reactions.

Effectiveness

Does Oak Moss work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by .

Evidence overview · 1 use evaluated
1 Insufficient evidence
How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.
2Likely EffectiveGood evidence, though not yet conclusive.
3Possibly EffectiveSome evidence suggests a benefit.
4Possibly IneffectiveSome evidence it may not help.
5Likely IneffectiveFairly strong evidence it doesn’t help.
6IneffectiveStrong evidence it doesn’t work.
7Insufficient Reliable Evidence to RateToo little research to say either way.

For Oak Moss, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 1 condition — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Cough
Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral oak moss for cough, there is insufficient reliable information about the clinical effects of cough for this purpose.<br/><nb> More evidence is needed to rate oak moss for this use.

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

Oak moss is widely used in perfumes, but it is a well-known skin allergen. In many regions, the amount allowed in cosmetics is limited because it can trigger allergic contact dermatitis (an itchy, red skin rash) in sensitive people.

Because oak moss is rarely used as an oral supplement, its safety when swallowed is not well studied. People with known fragrance or lichen allergies should be especially careful and may want to avoid it entirely.

Pregnancy and breastfeeding: There is no reliable safety information for taking oak moss during pregnancy or while breastfeeding. To be safe, avoid using it as a supplement during these times. If you use perfumes containing oak moss, that is generally a different and lower-level exposure, but talk with your doctor if you have concerns.

Always check with a pharmacist or doctor before using any new supplement, especially if you have allergies, a medical condition, or take other medicines.

Side effects

The most common problem with oak moss is allergic skin reactions. These can include redness, itching, rash, and irritation where a product touched the skin. People allergic to fragrances or other lichens are more likely to react.

Because oak moss is not commonly taken by mouth, side effects from swallowing it are not well documented. As with many lichen products, there is a theoretical risk of stomach upset or irritation.

If you develop a rash, swelling, trouble breathing, or other signs of an allergic reaction, stop using the product and seek medical care right away.

Oak Moss: Reported Adverse Effects

Documented safety reports on Oak Moss from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Orally, oak moss seems to be well tolerated when taken in small amounts, short-term. However, a high-quality assessment of safety has not been conducted. When oak moss is used long-term, in large amounts of tea, or as a hot alcoholic extract, it may be unsafe due to various constituents, including thujone and usnic acid.

Most Common Adverse Effects:

Topically: Oak moss may cause contact sensitivity and allergic reactions in people with lichen and moss allergy. Usnic acid, a constituent of oak moss, also can cause conjunctivitis, contact dermatitis, and local irritation.

Serious Adverse Effects (Rare):

Orally: Large amounts or long-term use of oak moss may cause convulsions, kidney damage, liver damage, restlessness, tremors, vertigo, and vomiting.

Reports by condition
Allergic rhinitis (hay fever) Dermatologic

Topically, use of oak moss may cause contact sensitivity and allergic reactions in people with lichen and moss allergy. In patch testing, very late reactions have occurred, some as late as 27 days after application. Usnic acid, a constituent of oak moss, also can cause allergic contact dermatitis with respiratory symptoms.

  1. Dahlquist I, Fregert S. Contact allergy to atranorin in lichens and perfumes. Contact Dermatitis 1980;6:111-9.
  2. Goncalo S. Contact sensitivity to lichens and compositae in Frullania dermatitis. Contact Dermatitis 1987;16:84-6.
  3. Goncalo S, Cabral F, Goncalo M. Contact sensitivity to oak moss. Contact Dermatitis 1988;19:355-7.
  4. Thune P, Solberg Y, McFadden N, et al. Perfume allergy due to oak moss and other lichens. Contact Dermatitis 1982;8:396-400.
  5. Schubert S, Schnuch A, Bauer A, et al. Very late reactions in the patch test with fragrance mix I and oak moss absolute (Evernia prunastri, INCI): Data of the Information Network of Departments of Dermatology (IVDK). Contact Dermatitis 2022;86(1):54-57.
  6. Ingolfsdottir K. Usnic acid. Phytochemistry 2002;61:729-36.
  7. Mitchell, J. C. Allergy to lichens. Allergic contact dermatitis from usnic acid produced by lichenized fungi. Arch Dermatol 1965;92(2):142-146.
  8. Rafanelli, S., Bacchilega, R., Stanganelli, I., and Rafanelli, A. Contact dermatitis from usnic acid in vaginal ovules. Contact Dermatitis 1995;33(4):271-272.
Conjunctivitis Ocular/Otic

Topically, usnic acid, a constituent of oak moss, can cause conjunctivitis.

  1. Ingolfsdottir K. Usnic acid. Phytochemistry 2002;61:729-36.
Fatigue Hepatic

Orally, usnic acid, a constituent of oak moss, has been associated with reports of hepatotoxicity. From July to December 2000 there were at least seven cases of acute hepatotoxicity in patients taking LipoKinetix, a product containing usnic acid as sodium usniate. Symptoms including nausea, weakness and fatigue, abdominal pain, and yellowing of the skin usually developed from 2 weeks to 3 months after starting LipoKinetix and resolved upon discontinuation. It is unclear if the sodium usniate ingredient is the cause of these adverse events. There are also individual case reports suggesting the development of hepatotoxicity related to the use of other weight loss products containing usnic acid.

  1. Favreau JT, Ryu Ml, Braunstein G, et al. Severe hepatotoxicity associated with the dietary supplement LipoKinetix. Ann Intern Med 2002;136:590-5.
  2. Durazo, F. A., Lassman, C., Han, S. H., Saab, S., Lee, N. P., Kawano, M., Saggi, B., Gordon, S., Farmer, D. G., Yersiz, H., Goldstein, R. L., Ghobrial, M., and Busuttil, R. W. Fulminant liver failure due to usnic acid for weight loss. Am.J Gastroenterol.
  3. Neff, G. W., Reddy, K. R., Durazo, F. A., Meyer, D., Marrero, R., and Kaplowitz, N. Severe hepatotoxicity associated with the use of weight loss diet supplements containing ma huang or usnic acid. J Hepatol. 2004;41(6):1062-1064.
  4. Hsu, L. M., Huang, Y. S., Chang, F. Y., and Lee, S. D. 'Fat burner' herb, usnic Acid, induced acute hepatitis in a family. J Gastroenterol.Hepatol. 2005;20(7):1138-1139.
  5. Arneborn, P., Jansson, A., and Bottiger, Y. [Acute hepatitis in a woman after intake of slimming pills bought via Internet]. Lakartidningen 7-11-2005;102(28-29):2071-2072.
  6. Sanchez, W., Maple, J. T., Burgart, L. J., and Kamath, P. S. Severe hepatotoxicity associated with use of a dietary supplement containing usnic acid. Mayo Clin Proc 2006;81(4):541-544.
Nausea and vomiting Gastrointestinal

Orally, large amounts or long-term use of thujone-containing products may cause vomiting.

  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
Vertigo Neurologic/CNS

Orally, large amounts or long-term use of thujone-containing products, such as oak moss, may cause convulsions, restlessness, tremors, and vertigo.

  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no established safe or effective oral dose for oak moss. It is not a standard dietary supplement, and reliable dosing information from human studies does not exist.

If you come across an oak moss product, follow the directions on the label and do not exceed them. For fragrance and cosmetic use, manufacturers follow regulatory limits on how much oak moss can be included.

Before using any oak moss product internally, check with a pharmacist or doctor. Given the lack of safety data, oral use is generally not recommended.

Pregnancy & Breastfeeding

Oak Moss & Pregnancy

Possibly Unsafe

When used orally. The constituent thujone shows evidence of uterine stimulant activity.

  1. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

Oak Moss & Breastfeeding

Possibly Unsafe

When used orally. The constituent thujone shows evidence of uterine stimulant activity.

  1. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

© 2026 Therapeutic Research Center

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 16 references that drive our Oak Moss monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  3. Dahlquist I, Fregert S. Contact allergy to atranorin in lichens and perfumes. Contact Dermatitis 1980;6:111-9. PubMed
  4. Goncalo S. Contact sensitivity to lichens and compositae in Frullania dermatitis. Contact Dermatitis 1987;16:84-6. PubMed
  5. Goncalo S, Cabral F, Goncalo M. Contact sensitivity to oak moss. Contact Dermatitis 1988;19:355-7. PubMed
  6. Thune P, Solberg Y, McFadden N, et al. Perfume allergy due to oak moss and other lichens. Contact Dermatitis 1982;8:396-400. PubMed
  7. Favreau JT, Ryu Ml, Braunstein G, et al. Severe hepatotoxicity associated with the dietary supplement LipoKinetix. Ann Intern Med 2002;136:590-5. PubMed
  8. Ingolfsdottir K. Usnic acid. Phytochemistry 2002;61:729-36.
  9. Mitchell, J. C. Allergy to lichens. Allergic contact dermatitis from usnic acid produced by lichenized fungi. Arch Dermatol 1965;92(2):142-146.
  10. Durazo, F. A., Lassman, C., Han, S. H., Saab, S., Lee, N. P., Kawano, M., Saggi, B., Gordon, S., Farmer, D. G., Yersiz, H., Goldstein, R. L., Ghobrial, M., and Busuttil, R. W. Fulminant liver failure due to usnic acid for weight loss. Am.J Gastroenterol. PubMed
  11. Neff, G. W., Reddy, K. R., Durazo, F. A., Meyer, D., Marrero, R., and Kaplowitz, N. Severe hepatotoxicity associated with the use of weight loss diet supplements containing ma huang or usnic acid. J Hepatol. 2004;41(6):1062-1064. PubMed
  12. Hsu, L. M., Huang, Y. S., Chang, F. Y., and Lee, S. D. 'Fat burner' herb, usnic Acid, induced acute hepatitis in a family. J Gastroenterol.Hepatol. 2005;20(7):1138-1139. PubMed
  13. Arneborn, P., Jansson, A., and Bottiger, Y. [Acute hepatitis in a woman after intake of slimming pills bought via Internet]. Lakartidningen 7-11-2005;102(28-29):2071-2072.
  14. Sanchez, W., Maple, J. T., Burgart, L. J., and Kamath, P. S. Severe hepatotoxicity associated with use of a dietary supplement containing usnic acid. Mayo Clin Proc 2006;81(4):541-544. PubMed
  15. Rafanelli, S., Bacchilega, R., Stanganelli, I., and Rafanelli, A. Contact dermatitis from usnic acid in vaginal ovules. Contact Dermatitis 1995;33(4):271-272. PubMed
Keep reading

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

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

Pharmacist Counseling Corner

Oak Moss: Common Questions

What is Oak Moss used for, and does it work?
People use Oak Moss for a range of reasons, but according to the Natural Medicines database the current clinical evidence is insufficient to confirm it works for the specific conditions it has been studied for. See the graded list on this page, and talk to your pharmacist or doctor before relying on it for any condition.
Does Oak Moss interact with prescription medications?
We do not currently list any known drug interactions for Oak Moss. This does not guarantee that none exist, so always confirm with your pharmacist before combining it with your medications.
How are Oak Moss interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Oak Moss with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Oak Moss interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
What is Oak Moss used for?
Oak Moss is mostly used as a perfume ingredient because of its earthy, woody scent and its ability to make fragrances last longer. It is rarely used as a health supplement, and there is little human evidence supporting medical uses.
Is Oak Moss safe to use?
In perfumes it is widely used but is a known skin allergen and can cause itchy rashes in sensitive people. Its safety when swallowed as a supplement has not been well studied, so caution is advised.
Can I use Oak Moss if I'm pregnant or breastfeeding?
There is no reliable safety data for Oak Moss during pregnancy or breastfeeding, so it is best to avoid using it as a supplement during these times.
Why does Oak Moss sometimes cause a rash?
Oak Moss contains compounds like atranorin that can trigger allergic contact dermatitis, leading to redness, itching, and irritation in people who are sensitive to fragrances or lichens.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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