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.20,21

We suspect millions of people would swear by their own experience that applying aloe to the skin can drastically reduce the time it takes for burns (including sunburns) to heal. But, there is conflicting evidence regarding aloe's benefits. Some studies suggest that aloe is not effective for treating sunburn and may actually impair the healing of second-degree burns.1,2However, a small randomized trial involving 30 people with second-degree burns found that treatment with aloe cream resulted in faster healing time compared to silver sulfadiazine cream, a common treatment for burns.39

Aloe also appears to be ineffective for treating the burn-like skin damage caused by radiation therapy for cancer. In a double-blind, placebo-controlled studyof 194 women undergoing radiation therapy for breast cancer, use of aloe gel failed to protect the skin from radiation-induced damage.7 Lack of benefit was also seen in an opentrial of 225 women.22One study evaluated aloe soap in 73 men and women undergoing radiation therapy for various forms of cancer and, overall, failed to find benefit except possibly at the highest doses.23 Another study failed to find aloe gel helpful for mouth inflammation caused by radiation therapyfor head and neck cancer.27

Besides its use for burns, aloe has been widely recommended for aiding wound healing. Results of test tube and animal studiesof aloe for wounds have been positive.3-5,24,25And a small randomized study involving 49 people recovering from hemorrhoid surgery found that aloe cream reduced pain and hastened wound healing.37But, one clinical report suggests that aloe can actually impair the healing of severe wounds.6Also, a review of 7 trials involving 347 people did not find evidence that aloe can improve wound healing.41

There is some evidence (although incomplete) that aloe cream might help genital herpes, lichen planus,psoriasis, and seborrhea. See below for more information.

Aloe gel has also been tried as a treatment to be taken internally by mouth. Two studies suggest that that aloe gel taken in this way might be helpful for type 2 diabetes.8,9 One study found possible benefits for ulcerative colitis.28

Very weak evidence hints that regular intake of aloe might decrease risk of kidney stones.32,33

Oral aloe is also sometimes recommended as an aid in the treatment of asthma, stomach ulcers, and general immune support, but there is no meaningful evidence that it is effective for any of these purposes.

One of the constituents of aloe gel, acemannan, has shown some promise in test tube and animal studies for stimulating immunity and inhibiting the growth of viruses.10-12 These finding have led to the suggestion that acemannan can help HIV infection. However, the one reported double-blind, placebo-controlled trial failed to show benefits.26