The succulent aloe plant has been valued since prehistoric times for the treatment of burns, wound infections, and other skin problems. Medicinal aloe is pictured in an ancient cave painting in South Africa, and Alexander the Great is said to have captured an island off Somalia for the sole purpose of possessing the luxurious crop of aloe found there.
Most uses of aloe refer to the gel inside its cactus-like leaves. However, the skin of the leaves themselves can be condensed to form a sticky substance known as drug aloe or aloes. It is a powerful laxative, but it is seldom used because its effects are unpleasant. The uses described below are intended to refer only to aloe gel, not to drug aloe. However, to make matters trickier, some aloe gel products contain small amounts of drug aloe, and it is possible that this contaminant is the actual source of benefits seen in some studies. ^
Topical aloe vera cream typically contains 0.5% aloe and is applied three times daily.
For the treatment of diabetes, a dosage of 1 tablespoon of aloe juice twice daily has been used in studies.
What Is the Scientific Evidence for Aloe?
A 2-week, double-blind, placebo-controlled trial enrolled 60 men with active genital herpes . ^ Participants applied aloe cream (0.5% aloe) or placebo cream 3 times daily for 5 days. Use of aloe cream reduced the time necessary for lesions to heal (4.9 days versus 12 days), and also increased the percentage of individuals who were fully healed by the end of 2 weeks (66.7% versus 6.7%).
A previous double-blind, placebo-controlled study by the same author, enrolling 120 men with genital herpes, found that cream made from aloe was more effective than pure aloe gel or placebo. ^
Seborrhea is a fairly common skin condition, leading to oily, red, and scaly eruptions in such areas as the eyebrows, eyelids, nose, ear, upper lip, chest, groin, and chin. A double-blind, placebo-controlled study of 44 individuals found that 4 to 6 weeks of treatment with aloe ointment could significantly reduce symptoms of seborrhea. ^
According to a double-blind study that enrolled 60 men and women with mild to moderate symptoms of psoriasis , aloe cream may be helpful for this chronic skin condition. ^ Participants were treated with either topical aloe extract (0.5%) or a placebo cream, applied 3 times daily for 4 weeks. Aloe treatment produced significantly better results than placebo, and these results were said to endure for almost a year after treatment was stopped. The study authors also reported a high level of complete "cure," but what exactly they meant by this was not reported clearly.
However, another study failed to replicate these results. ^ Over four weeks of treatment, marked improvement was seen in 72.5% of skin patches treated with aloe, but 82% of those treated with placebo. This was a statistically significant difference in favorof placebo.
Further studies will be needed to sort out these contradictory results.
Lichen planus is a chronic skin condition characterized by itchy, flat, scaly patches. It can occur in various parts of the body, including the wrists, legs, trunk, mouth, and vagina.
One study evaluated the potential value of aloe vera as a topical treatment for oral lichen planus. ^ In this double-blind, placebo controlled study of 54 people with oral lichen planus, use of aloe vera gel was significantly more effective than placebo in alleviating symptoms. In another study involving 34 women with lichen planus of the vulva (just outside the vagina), aloe vera led to significantly more improvement than placebo. ^
Evidence from two human trials suggests that aloe gel can improve blood sugar control in individuals with type 2 diabetes .
A single-blind, placebo-controlled trial evaluated the potential benefits of aloe in either 72 or 40 individuals with diabetes (the study report appears to contradict itself). ^ The results showed significantly greater improvements in blood sugar levels among those given aloe over the 2-week treatment period.
Another single-blind, placebo-controlled trial evaluated the benefits of aloe in individuals who had failed to respond to the oral diabetes drug glibenclamide. ^ Of the 36 individuals who completed the study, those taking glibenclamide and aloe showed definite improvements in blood sugar levels over 42 days as compared to those taking glibenclamide and placebo.
Although these are promising results, large studies that are double- rather than single-blind will be needed to establish aloe as an effective treatment for hypoglycemia.
In a double-blind, placebo-controlled study of 44 people with active ulcerative colitis , use of oral aloe gel at a dose of 100 ml twice daily for 4 weeks appeared to improve both subjective symptoms and objective measurements of disease severity. ^ About half of the people given aloe showed response to treatment; about 30% experienced full remission. Benefits occurred only rarely in the placebo group. However, this was a small study, and its results can't be taken as conclusive.