Lemongrass, a perennial grass used as an infusion in teas as well as in oils, has medical uses as well as use as a flavoring or as a tea. Although lemongrass is generally recognized as safe in the United States, it's not approved for use by the German Commission E, the regulating agency for supplements. Lemongrass contains ingredients that may have side effects that make it unsafe for use in pregnancy, although human studies have not been done.
Several grasses make up lemongrass. Cymbopogon citratus and C. flexuosus are grown in different areas and contain different ingredients. C. citratus, which grows in the West Indies, Central and South America, and tropical regions, contains citral and myrcene, two substances that could cause potentially harmful effects in pregnancy, according to Memorial Sloan-Kettering Cancer Center. Cymbopogon flexuosus contains isointermedeol, geraniol, alpha-bisabolol and limonene.
Potential Fetal Effects
Studies on the reproductive effects of lemongrass have been conducted on animals only, testing citral and myrcene. A Brazilian study published in the July 1998 issue of the "Brazilian Journal of Medical and Biological Research" found that only at very high doses, 500 mg per kilogram, myrcene increased the pregnancy loss rate and increased the rate of fetal skeletal abnormalities in Wistar rats. Developmental delays such as delayed eye opening and incisor eruption occurred in exposed offspring. Another Brazilian study, which appeared in the February 1995 issue of "Toxicology" found an increased rate of skeletal malformations as well as fetal growth retardation in Wistar rats at doses of 60 mg/kg. An increased pregnancy loss rate also occurred at this dose.
Potential Maternal Effects
Lemongrass oil can damage the liver and stomach lining. The Brazilian study reported in "Toxicology" found that maternal toxicity evidenced by decreased weight also occurred, although a 1998 study in the "Brazilian Journal of Medical and Biological Research" noted only that liver and kidney weights increased in adult rats.
Other Side Effects
Other side effects of lemongrass include dizziness, drowsiness, dry mouth and increased appetite. Allergic reactions also can occur. Lemongrass also may lower blood glucose levels and blood pressure. Because myrcene can interfere with cytochrome P450 liver enzymes, your body may not be able to break down medications well, which could increase their effects.
Substances like lemongrass rarely undergo human testing during pregnancy, since adverse effects could harm a growing fetus. Results obtained from animal studies don't always give the same results as those seen in humans. The safest thing to do when you're pregnant is to avoid any potentially harmful substance, including lemongrass.