The herb rosemary has been used as a food spice and as a medicine since ancient times. Traditional medicinal uses of rosemary leaf preparations taken internally include digestive distress, headaches, and anxiety. The fragrance of rosemary leaf has been said to enhance memory. Rosemary oil was applied to the skin to treat muscle and joint pain and taken internally to promote abortions.
Germany’s Commission E has approved rosemary leaf for treatment of dyspepsia (non-specific digestive distress) and rosemary oil (used externally) for joint pain and poor circulation. However, there is no meaningful scientific evidence that rosemary is effective for any of these uses. Only double-blind , placebo-controlled studies can prove that a treatment really works, and no studies of this type have found rosemary effective. (For information on why such studies are essential, see Why Does This Database Rely on Double-blind Studies? )
Rosemary essential oil, like many essential oils, has antimicrobial properties when it comes in direct contact with bacteria and other microorganisms. 1-5 Note, however, that is does not mean that rosemary oil is an antibiotic. Antibiotics are substances that can be taken internally to kill microorganisms throughout the body. Rosemary oil, rather, has shown potential antiseptic properties.
Rosmarinic acid from rosemary has shown potential anti-inflammatory and anti-allergic actions, but most published studies (including double-blind trials) have used a different plant source of the substance (the herb Perilla frutescens ). 17-22
One controlled study failed to find rosemary cream protective against skin irritation caused by sodium lauryl-sulfate (a common ingredient of cosmetic products). 23
Rosemary essential oil has been used in aromatherapy (treating conditions through scent). One controlled study evaluated rosemary aromatherapy for enhancing memory, but found results that were mixed at best. 24 Another study failed to find that rosemary aromatherapy reduced tension during an anxiety-provoking task; in fact, it appeared that use of rosemary actually increased anxiety. 25
A typical dosage of rosemary leaf is 4-6 grams daily. Rosemary essential oil should not be used internally.
Although rosemary’s use as a food spice suggests a relatively low level of toxicity, rosemary has not undergone comprehensive safety testing. Rosemary essential oil can be toxic if taken even in fairly low doses, and the maximum safe dose is not known.
Based on its traditional use for abortion, as well as preliminary evidence showing embryotoxic effects, 26 rosemary should not be used by pregnant women or women who wish to become pregnant.
Other weak evidence hints that rosemary may enhance the liver’s rate of deactivating estrogen in the body. 28 This suggests that rosemary might present risks for females, as well as anyone who uses medications containing estrogen.
1. Santoyo S, Cavero S, Jaime L, et al. Chemical composition and antimicrobial activity of Rosmarinus officinalis L. essential oil obtained via supercritical fluid extraction. J Food Prot . 2005;68:790-795.
4. Mangena T, Muyima NY. Comparative evaluation of the antimicrobial activities of essential oils of Artemisia afra , Pteronia incana and Rosmarinus officinalis on selected bacteria and yeast strains. Lett Appl Microbiol . 1999;28:291-296.
8. Zhu BT, Loder DP, Cai MX, et al. Dietary administration of an extract from rosemary leaves enhances the liver microsomal metabolism of endogenous estrogens and decreases their uterotropic action in CD-1 mice. Carcinogenesis . 1998;19:1821-1827.
9. Singletary KW, Nelshoppen JM. Inhibition of 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumorigenesis and of in vivo formation of mammary DMBA-DNA adducts by rosemary extract. Cancer Lett . 1991;60:169-175.
10. Slamenova D, Kuboskova K, Horvathova E, et al. Rosemary-stimulated reduction of DNA strand breaks and FPG-sensitive sites in mammalian cells treated with H2O2 or visible light-excited Methylene Blue. Cancer Lett . 2002;177:145-153.
14. Hoefler C, Fleurentin J, Mortier F, et al. Comparative choleretic and hepatoprotective properties of young sprouts and total plant extracts of Rosmarinus officinalis in rats. J Ethnopharmacol . 1987;19:133-143.
17. Osakabe N, Takano H, Sanbongi C, et al. Anti-inflammatory and anti-allergic effect of rosmarinic acid (RA); inhibition of seasonal allergic rhinoconjunctivitis (SAR) and its mechanism. Biofactors . 2005;21:127-131.
18. Takano H, Osakabe N, Sanbongi C, et al. Extract of Perilla frutescens enriched for rosmarinic acid, a polyphenolic phytochemical, inhibits seasonal allergic rhinoconjunctivitis in humans. Exp Biol Med (Maywood) . 2004;229:247-254.
22. Osakabe N, Yasuda A, Natsume M, et al. Rosmarinic acid inhibits epidermal inflammatory responses: anticarcinogenic effect of Perilla frutescens extract in the murine two-stage skin model. Carcinogenesis . 2004;25:549-557.
23. Fuchs SM, Schliemann-Willers S, Fischer TW, et al. Protective effects of different marigold ( Calendula officinalis L.) and rosemary cream preparations against sodium-lauryl-sulfate-induced irritant contact dermatitis. Skin Pharmacol Physiol . 2005;18:195-200.
28. Zhu BT, Loder DP, Cai MX, et al. Dietary administration of an extract from rosemary leaves enhances the liver microsomal metabolism of endogenous estrogens and decreases their uterotropic action in CD-1 mice. Carcinogenesis . 1998;19:1821-1827.
Last reviewed July 2012 by EBSCO CAM Review Board
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