The diterpenes in the volatile oil have also shown anti-allergic activity. 6 Water extracts may help reduce ulcers. 7 Test tube studies also show that cinnamon can augment the action of insulin . However, use of cinnamon to improve the action of insulin in diabetics has yet to be proven in clinical studies. No more than a few drops of essential oil should be used and only for a few days at a time.
Some individuals develop allergies and dermatitis after exposure to cinnamon.
Therefore, only small amounts should be used initially in persons who have not previously had contact with cinnamon, and anyone with a known allergy should avoid it. Chronic use may cause inflammation in the mouth. The concentrated oil is more likely to cause problems. According to the German Commission E monograph, cinnamon is not recommended for use by pregnant women. At the time of writing, there were no well-known drug interactions with cinnamon.