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.

What Is Rosemary Used for Today?

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.

One animal study found evidence that rosemary might help withdrawal from narcotics.6

Even weaker evidence hints that rosemary or its constituents may have antithrombotic (“blood thinning”),7 anticancer,8-11 diuretic,12 liver-protective,13-15 and ulcer-protective effects.16

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

Dosage

A typical dosage of rosemary leaf is 4-6 grams daily. Rosemary essential oil should not be used internally.

Safety Issues

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.

One study suggests that rosemary may have diuretic effects.12 If it does, the herb could theoretically present risks in people taking the medication lithium.27

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.

Additionally, one study hints that rosemary might worsen blood sugar control in people with diabetes.29

Interactions You Should Know About

If you are taking:

  • Lithium: Use rosemary only with caution.
  • Medications containing estrogen: Rosemary may decrease their effect.