What is Rosemary?

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 2 3 4} Note, however, that is does not mean that rosemary oil is an antibiotic....

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, ⁵ rosemary should not be used by pregnant women or women who wish to become pregnant.

One study suggests that rosemary may have diuretic effects. ⁶ If it does, the herb could theoretically present risks in people taking the medication lithium . ⁷ Other weak evidence hints that rosemary may enhance the liver’s rate of deactivating estrogen in the body. ⁸ This suggests that rosemary might present risks for...