Q. How effective is aloe vera in helping to heal wounds, burns, rashes or anything else?

A. To answer this question, I looked at all aloe vera studies done from 1950 to June 2007 that I could find online.

If you did a study on a hundred people with itchy rashes and had them use creams with no aloe or medication, your study would show that the creams reduce itching. This is because of the power of suggestion, the so-called placebo effect. To find out whether something really works beyond the power of suggestion, you must rely on experimental studies — studies that randomly assign folks with rashes or other ailments either a placebo (a "fake" cream or pill without the active ingredient) or the real McCoy, and compare the results of the two groups

Looking only at these randomized, controlled trials for aloe, I found some interesting information. A study published in Obstetrics & Gynecology in July, 1991, looked at women who had wound complications after gynecologic surgery, and found that wounds treated with aloe vera gel took longer to heal — 83 days, compared with 53 days in those treated with usual care. However, this was a small study with possible flaws in its analysis of the data.

Patients undergoing radiation therapy for breast cancer commonly experience skin redness, peeling, itching and even open sores. Researcher Sue Heggie led a team that studied whether aloe vera gel could reduce these complications. The study, published in the December 2002 issue of Cancer Nursing, found that aloe vera actually caused more itching, pain and peeling compared with another cream.

Randomized studies on burns likewise show little benefit. According to a September 2005 study from the Journal of the Medical Association of Thailand, aloe vera cream conferred no sunburn or suntan protection and was ineffective in treating sunburns. I found only one study, also from this journal but from August 1995, that found that aloe vera helped burns heal faster — but it was a small study and its authors recommended that further studies be done.

Other studies show no benefit from aloe cream in the treatment of cold sores, pressure ulcers, eczema, or, in pill form, for various other conditions, such as irritable bowel syndrome. Also, aloe gel may increase bleeding in patients on blood thinners like warfarin.

In summary, I find little rationale for the use of aloe vera, or for its inclusion in skincare products or in supplements taken orally.

Dr. Landis Lum is a family-practice physician for Kaiser Permanente and an associate clinical professor at the University of Hawai'i's John A. Burns School of Medicine. Send your questions to: Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; islandlife@honoluluadvertiser.com; or fax 535-8170. This column is not intended to provide medical advice.