The absence of toxicity signals or symptoms in mice, whether treated acutely or repeatedly, at the doses used in the present study shows the relative safety of the EO. The absence of a deleterious effect on the morphological structure of the stomach or liver in rats treated sub-acutely with doses up to 1500 mg/kg has been described previously (Fandohan et al., 2008). However, the major compound in the EO from Cymbopogon citratus induced maternal toxicity in pregnant rats at doses higher than 125 mg/kg (Nogueira et al., 1995). This observation confirms that acute toxicity data limit the pre-clinical applications of the EO because a cumulative toxic effect does occur even at very low doses (Mabeku et al., 2007), reinforcing the importance of complementary toxicological studies to evaluate the safety of the EO as a complementary therapy in folk medicine.