ESSENTIAL PLANT OILS AND HEADACHE MECHANISMS

The rationale for using essential oils to alleviate headache is based on several assumptions. Especially for peppermint oil certain analgesi c mechanisms were recently described. Local application of peppermint oil generates a long-lasting cooling effect on the skin, caused by a s teric alteration of the calcium channels of the cold-receptors. Furthe r it was shown that peppermint oil inhibits non-competively 5-hydroxyt ryptamin (serotonine) and substance P induced smooth muscle contractio n in animal-models. It is also known that peppermint oil induces a sig nificant increase of the skin blood flow of the forehead after local a pplication, measured by laser doppler. Assuming that a clinical releva nt analgesic action exists, this ought to be observable in experimenta l algesimetric human tests. Therefore the effects of peppermint oil an d eucalyptus oil preparations on neurophysiological, psychological and experimental algesimetric parameters were investigated in 32 healthy subjects in a double-blind, placebo-controlled, randomized cross-over design. Four different test preparations were used: preparation 1 (LI1 701) consisted of 10 g peppermint oil and 5 g eucalyptus oil plus etha nol 90% to 100 g; preparation 2 (LI1702) of 10 g peppermint oil and tr aces of eucalyptus oil plus ethanol 90% to 100 g; preparation 3 (LI170 3) of traces of peppermint oil and 5 g eucalyptus oil plus ethanol 90% to 100 g; and preparation 4 (placebo) of traces of peppermint oil and traces of eucalyptus oil plus ethanol 90% to 100 g. The test preparat ions were applied to large areas of the forehead and temples using a s mall sponge. The treatment effect of the preparations was evaluated by comparing baseline and treatment measurements. The combination of pep permint oil, eucalyptus oil and ethanol can increase cognitive perform ance while having a muscle-relaxing and mentally relaxing effect, but has little influence on pain sensitivity. A significant analgesic effe ct with a reduction in sensitivity to headache is however produced by the combination of peppermint oil and ethanol. The essential plant oil preparations can thus be shown by laboratory tests to exert significa nt effects on mechanisms associated with the pathophysiology of clinic al headache syndromes. Further, to investigate the efficacy of essenti al oil preparations compared to usual analgesics (paracetamol or acety lsalicylicacid) a double blind, placebo controlled, randomized study s hould be performed.