Summary of Peppermint and Eucalyptus essential oils for headaches, by Don Brown: Thirty-two healthy volunteers were entered in a study to investigate the neurophysiological and psychological effects of topical preparations peppermint oil and eucalyptus oil, traditionally used to treat tension headaches. The study was a double-blind, placebo-controlled, randomized cross-over design. Subjects were initially randomized to one of four treatment groups: (1) 100 g combination of 10 g peppermint oil and 5 g eucalyptus oil plus ethanol; (2) 100 g combination of 10 g peppermint oil and traces of eucalyptus oil, plus ethanol; (3) 100 g combination of traces of peppermint and 5 g eucalyptus oil, plus ethanol; (4) placebo preparation with traces of eucalyptus oil, peppermint oil, plus ethanol.
The test preparations were applied to large areas of the forehead and temples for three minutes with a small sponge. The application occurred three times: immediately after, 15 minutes after and 30 minutes after baseline measurements. Each subject received the four different preparations on four different test days separated by at least one day of washout. The tests occurred between 3 p.m. and 6 p.m. to control for any variation in circadian rhythms.
EMG activity of the temporal muscle under relaxation (increased surface tension of EMG is a concomitant symptom of tension-type headaches), exteroceptive suppression periods of temporal muscle activity, contingent negative variation (this measure increases in amplitude in patients with migraine without aura), sensitivity to experimentally induced pain, thermal pain induction, ischemically induced headache, and current mood states were all used to measure the subjects’ responses to the different preparations.
The application of test preparations 3 and 4 had no significant effects on the test parameters. Test preparation 1 had the most significant effect, muscle relaxation. It had little effect, however, on pain sensitivity. Test preparation 2 had the most significant analgesic effect and led to the greatest reduction in the sensitivity to headache.
Comments/Opinions: Most of our conversations about essential oils in the Quarterly Review of Natural Medicine (QRNM) have been limited to topical use as antimicrobials and the use of lavender oil in baths to reduce perineal discomfort following childbirth. This study opens the door for the potential topical use of peppermint and eucalyptus oil as an alternative therapy for the treatment of headaches. It should be noted, however, that this is not a new concept. Essential oils have been used topically as analgesics for hundreds of years. We’re all used to seeing BENGAY and other menthol-containing rubs in the over-the-counter market for the treatment of muscle soreness and stiffness.
While the exact mechanism of action of these topical medicaments remains to be shown, we know the following: local application of peppermint oil generates a cooling effect on the skin; peppermint oil non-competitively inhibits serotonin and substance P-induced smooth muscle contraction in animals; both oils are well-known transmitters in the trigemino-vascular system, which is the leading structure in generating primary headaches. The authors point out that peppermint oil relaxes pericranial muscles by blocking calcium channels.
Tension-type headaches are the most common primary headache syndrome. Millions of dollars are spent annually for analgesics that are wrought with potential side effects. Topical use of peppermint oil, either alone or in combination with eucalyptus oil, may prove to be a simple, cost-effective alternative. Further studies should be done comparing their effects in comparison to those of aspirin and acetaminophen. According to the authors of this study, a study comparing topical essential oil therapy with acetaminophen is currently under way in Germany.
[Göbel H, G. Schmidt, M. Dworshak, at al. 1995. Essential plant oils and headache mechanisms. Phytomedicine. 2(2): 93-102.]