Peppermint:

http://www.umm.edu/altmed/ConsHerbs/Peppermintch.html

Peppermint oil has exhibited antiviral properties against a number of infectious agents, including herpes.

Peppermint (Mentha x piperita), a popular flavoring for gum, toothpaste, and tea, also serves as a calming agent to soothe an an upset stomach or to aid in digestion. Because it has a calming and numbing effect, it has been used to treat headaches, skin irritations, anxiety associated with depression, nausea, diarrhea, menstrual cramps, and flatulence. It is also widely used to treat symptoms of the common cold. These and other conditions for which peppermint may be beneficial are listed below.

http://www.swedish.org/110998.cfm

Peppermint oil is often used in combination with other essential oils to treat minor indigestion.

http://www.healingpeople.com/index.php?option=com_staticxt&staticfile=encyclopedia/pg000220.html

Peppermint tea also has a long history of medicinal use, primarily as a digestive aid and for the symptomatic treatment of cough, colds, and fever. Peppermint oil is used for chest congestion (Vicks VapoRub), as a local anesthetic (Solarcaine, Ben-Gay), and most recently in the treatment of irritable bowel disease, also known as spastic colon.

Germany's Commission E authorizes the use of peppermint oil for treating colicky pain in the digestive tract, specifically irritable bowel syndrome, as well as for relieving mucus congestion of the lungs and sinuses caused by colds and flus.

There is also some evidence that it might be helpful for gallstones.1 Peppermint is sometimes recommended for the treatment of candida yeast infections, but there is as yet no real evidence that it works.

http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-peppermint.html

Multiple randomized controlled trials of peppermint suggest significant improvements in irritable bowl syndrome (IBS) symptoms. Although the mechanism of action is not clear, pre-clinical studies suggest smooth muscle relaxing properties of peppermint (calcium antagonism may play a role). Enteric-coated peppermint preparations are generally recommended. Overall, studies have been brief with small sample sizes and methodological weaknesses (unclear diagnostic criteria, lack of validated measurement scales, unclear blinding and randomization procedures). Well-designed large trials are necessary before a strong recommendation can be made. Future studies should use standardized symptom scales and established diagnostic criteria to classify patients proir to enrollment (such as Rome II Diagnostic Criteria), uniform dosing and standardization, and longer duration.

A double-blind, placebo-controlled study including 39 individuals found that an enteric-coated peppermint-caraway oil combination taken three times daily for 4 weeks significantly reduced dyspepsia pain as compared to placebo.15 Of the treatment group, 63.2% was pain free after 4 weeks, compared to 25% of the placebo group.

1. Somerville KW, Ellis WR, Whitten BH, et al. Stones in the common bile duct: experience with medical dissolution therapy. Postgrad Med J. 1985;61:313–316.

2. Gunn JW. The carminative action of volatile oils. J Pharmacol Exp Ther. 1920;16:39–47.

3. Taylor BA, Luscombe DK, Duthie HL. Inhibitory effect of peppermint on gastrointestinal smooth muscle [abstract]. Gut. 1983;24:A992.

4. Hawthorn M, Ferrante J, Luchowski E, et al. The actions of peppermint oil and menthol on calcium channel dependent processes in intestinal, neuronal and cardiac preparations. Aliment Pharmcol Ther. 1988;2:101–118.

5. Rees WD, Evans BK, Rhodes J. Treating irritable bowel syndrome with peppermint oil. Br Med J. 1979;2:835–836.

6. Dew MJ, Evans BK, Rhodes J. Peppermint oil for the irritable bowel syndrome: a multicentre trial. Br J Clin Pract. 1984;38:394, 398.

7. Liu JH, Chen GH, Yeh HZ, et al. Enteric-coated peppermint-oil capsules in the treatment of irritable bowel syndrome: a prospective, randomized trial. J Gastroenterol. 1997;32:765–768.

8. Nash P, Gould SR, Barnardo DE. Peppermint oil does not relieve the pain of irritable bowel syndrome. Br J Clin Pract. 1986;40:292–293.

9. Lawson MJ, Knight RE, Tran K, et al. Failure of enteric-coated peppermint oil in the irritable bowel syndrome: a randomized double-blind crossover study. J Gastroenterol Hepatol. 1988;3:235–238.

10. Carling L, Svedberg LE, Hulten S. Short-term treatment of the irritable bowel syndrome: a placebo controlled trial of peppermint oil against hyoscyaminme. Opusc Med. 1989;34:55–57.

11. May B, Kuntz H-D, Kieser M, et al. Efficacy of a fixed peppermint oil/caraway oil combination in non-ulcer dyspepsia. Arzneimittelforschung. 1996;46:1149–1153.

12. Madisch A, Heydenreich CJ, Wieland V, et al. Treatment of functional dyspepsia with a fixed peppermint oil and caraway oil combination preparation as compared to cisapride. A multicenter, reference-controlled double-blind equivalence study. Arzneimittelforschung. 1999;49:925–932.

13. Westphal J, Horning M, Leonhardt K. Phytotherapy in functional upper abdominal complaints. Results of a clinical study with a preparation of several plants. Phytomedicine. 1996;2:285–291.

14. Spindler P, Madsen C. Subchronic toxicity study of peppermint oil in rats. Toxicol Lett. 1992;62:215–220.

15. European Scientific Cooperative on Phytotherapy. Menthae Piperitae Aetheroleum (peppermint oil). Exeter, UK: ESCOP, 1996–1997:1–6. Monographs on the Medicinal Uses of Plant Drugs, Fascicule 3.

16. European Scientific Cooperative on Phytotherapy. Menthae Piperitae Aetheroleum (peppermint oil). Exeter, UK: ESCOP, 1996–1997:5. Monographs on the Medicinal Uses of Plant Drugs, Fascicule 3.