Related Terms

• Ab-Solution plus®, ascorbic acid, atranorin, barbatic acid, binan, depsides, depsidones, diffractaic acid, dihydrousnic acid, evernic acid, glutinol, isoanhydromethyldihydrousnic acid, isodihydrousnic acid, isolichenin, isomethoxide, lichen, Lipokinetix®, longissiminone A, longissiminone B, methylusnic acid, oak moss extract, old man's beard, parmeliaceae, raffinose, sodium usnate, sodium usnic acid, tree's dandruff, tree moss, woman's long hair, Usnea amblyoclada, Usnea barbata, Usnea complanta, Usnea dasypoga, Usnea diffracta, Usnea fasciata, Usnea florida, Usnea ghattensis, Usnea hirta, Usnea longissima, Usnea rubiginea, Usnea siamensis, Usnea subfloridana, Usneaceae (family), usnic acid, usno, Zeta-N®.

Background

• Usnea species are classified as fruticose lichens, which are a symbiosis of fungus and algae. Usnea grows on the bark and wood of coniferous (e.g., spruces, firs, and pines) and deciduous hardwood (e.g., oak, hickory, walnut, apple, and other fruit trees) host trees throughout the northern hemisphere in Asia, Europe, and North America.

• Usnea has been used as a therapeutic agent in traditional Chinese medicine (TCM) for thousands of years. Usnea longissima is traditionally taken by mouth for lung and upper respiratory infections, and applied on the skin to treat surface infections or external ulcers. It is still used today in TCM in liquid extract and tincture form to treat tuberculosis lymphadenitis.

• Usnic acid is a secondary metabolite uniquely found in all lichens. Usnea or usnic acid has been used as a human papillomavirus (HPV) treatment and as an oral hygiene agent, with limited effectiveness.

• Usnic acid is also found in various oral (by mouth) dietary supplements, including Lipokinetix®, marketed as a weight loss agent. However, Lipokinetix® may not be safe and may cause liver damage. Lipokinetix®, now withdrawn from the market, contained phenylpropanolamine (PPA), caffeine, yohimbine hydrochloride, diiodothyronine and usnic acid.

Scientific Evidence

Tradition/Theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious and should be evaluated by a qualified health care professional.

• Analgesic (pain reliever), antibacterial, anticoagulant (blood thinning), antifungal, anti-inflammatory, antioxidant, antiparasitic, antipyretic (fever reducer), antiviral, cancer, deodorant, gastric ulcers, headache, lupus, oral hygiene, sunscreen, sunstroke, tetanus, tuberculosis, weight loss, wound healing.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older):

• There is no proven safe or effective dose. However, the German Commission E has approved 1 usnea lozenge (equivalent of 100 milligrams powdered usnea lichen) 3-6 times daily for mouth irritation. Usnea has also been taken by mouth as a powder (100 milligrams three times a day), tea, or tincture (3-4 milliliters three times daily). Usnea has also been applied on the affected area(s) of the skin two or three times daily.

Children (younger than 18 years):

• There is no proven safe or effective dose for usnea in children, and use is not recommended.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

• Avoid in individuals with a known allergy or hypersensitivity to usnea, its constituents, or related lichens. Usnea and its constituents have been reported to cause allergic reactions, such as skin rash, in individuals handling usnea, or using usnic acid vaginally. Deodorant sprays containing usnic acid have been linked to allergic contact eczema.

Side Effects and Warnings

• It appears that usnea is not well tolerated in humans except when applied on the skin or used as a homeopathic agent. The chemical constituent usnic acid has been reported in laboratory studies to be toxic, and dietary supplement products containing usnic acid have been reported to cause liver damage. Based on available research, only preparations of homeopathic usnea are recommended for oral (taken by mouth) use at this time.

• Usnea and usnic acid may cause contact dermatitis that may lead a hypersensitivity reaction, including urticaria ("hives"), rhinitis (runny or congested nose), asthma, or photoallergic contact dermatitis.

• Although not well studied in humans, usnic acid may increase the risk of bleeding. Caution is advised in patients with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.

Pregnancy and Breastfeeding

• Usnea or usnic acid is not recommended in pregnant or breastfeeding women based on a lack of available scientific evidence.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

• Usnea may increase bleeding time by inhibition of platelet aggregation. Caution is advised in patients with bleeding disorders or taking drugs that may increase the risk of bleeding. Some examples of drugs that increase the risk of bleeding include aspirin, anticoagulants (blood thinners) such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix ®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®). Dosing adjustments may be necessary.

• Usnea may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be decreased in the blood, and reduce the intended effects. Patients taking any medications should check the package insert and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.

Interactions with Herbs and Dietary Supplements

• Usnea may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

• Usnea may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements may become too low in the blood. It may also alter the effects that other herbs or supplements potentially may have on the P450 system.

Author Information

• This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

1. Aalto-Korte K, Lauerma A, Alanko K. Occupational allergic contact dermatitis from lichens in present-day Finland. Contact Dermatitis 2005;52(1):36-38. View Abstract

2. Arneborn P, Jansson A, Bottiger Y. [Acute hepatitis in a woman after intake of slimming pills bought via Internet]. Lakartidningen 7-11-2005;102(28-29):2071-2072. View Abstract

3. Behera BC, Verma N, Sonone A, et al. Antioxidant and antibacterial activities of lichen Usnea ghattensis in vitro. Biotechnol Lett 2005;27(14):991-995. View Abstract

4. Behera BC, Verma N, Sonone A, et al. Evaluation of antioxidant potential of the cultured mycobiont of a lichen Usnea ghattensis. Phytother.Res 2005;19(1):58-64. View Abstract

5. Choudhary MI, Azizuddin Jalil S, Atta ur Rahman. Bioactive phenolic compounds from a medicinal lichen, Usnea longissima. Phytochemistry 2005;66(19):2346-2350. View Abstract

6. De Carvalho EA, Andrade PP, Silva NH, et al. Effect of usnic acid from the lichen Cladonia substellata on Trypanosoma cruzi in vitro: an ultrastructural study. Micron. 2005;36(2):155-161. View Abstract

7. Halici M, Odabasoglu F, Suleyman H, et al. Effects of water extract of Usnea longissima on antioxidant enzyme activity and mucosal damage caused by indomethacin in rats. Phytomedicine 2005;12(9):656-662. View Abstract

8. Hsu LM, Huang YS, Chang FY, et al. 'Fat burner' herb, usnic Acid, induced acute hepatitis in a family. J Gastroenterol.Hepatol. 2005;20(7):1138-1139. View Abstract

9. Kathirgamanathar S, Williams DE, Andersen RJ, et al. Beta-orcinol depsidones from the lichen Usnea sp. from Sri Lanka. Nat Prod Res 2005;19(7):695-701. View Abstract

10. Lee KA, Kim MS. Antiplatelet and antithrombotic activities of methanol extract of Usnea longissima. Phytother Res 2005;19(12):1061-1064. View Abstract

11. Mayer M, O'Neill MA, Murray KE, et al. Usnic acid: a non-genotoxic compound with anti-cancer properties. Anticancer Drugs 2005;16(8):805-809. View Abstract

12. Odabasoglu F, Cakir A, Suleyman H, et al. Gastroprotective and antioxidant effects of usnic acid on indomethacin-induced gastric ulcer in rats. J Ethnopharmacol 1-3-2006;103(1):59-65. View Abstract

13. Saenz MT, Garcia MD, Rowe JG. Antimicrobial activity and phytochemical studies of some lichens from south of Spain. Fitoterapia 2006;77(3):156-159. View Abstract

14. Sanchez W, Maple JT, Burgart LJ, et al. Severe hepatotoxicity associated with use of a dietary supplement containing usnic acid. Mayo Clin Proc 2006;81(4):541-544. View Abstract

15. Wang XP, Liu HJ, Zhen L, et al. [Plasmid elimination effect of usnic acid on antibiotic-resistant Staphylococcus aureus]. Zhong.Yao Cai. 2006;29(1):36-39. View Abstract