Rosemary oil is a strong antioxidant, contributes substantially to the calming and soothing of tense nerves and muscles. Rosemary leaf is used as an analgesic, headache remedy, muscle stimulant and antimalarial, aids digestion and relieves cramps. Large doses of rosemary oil and other rosemary preparations can put pregnancy at risk. Avoid using rosemary oil in any amount if you are pregnant. Small doses can cause stomach, kidney and intestinal problems, and large amounts can be poisonous. If you're pregnant, avoid using the herb altogether medicinally, although it's okay to use as a seasoning