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 sunburn ) to heal. However, scientific evidence fails to support this belief. Studies suggest that aloe is not effective for treating sunburn and may actually impair the healing of second-degree burns. 1,2
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 study of 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 open trial of 225 women. 22 One 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 therapy for head and neck cancer. 27
Besides its use for burns, aloe has been widely recommended for aiding wound healing . However, while the results of test tube and animal studies of aloe for wounds have been positive, 3-5,24,25 one clinical report in people suggests that aloe can actually impair the healing of severe wounds. 6
Does topical aloe provide any benefit at all? There is some evidence (although quite incomplete) that it 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
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
A 2-week, double-blind, placebo-controlled trial enrolled 60 men with active genital herpes . 13 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. 14
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. 16
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. 15 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. 31 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 favor of 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. 35 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. 36
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). 17 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. 18 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. 29 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.
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.
Other than occasional allergic reactions, no serious problems have been reported with aloe gel, whether used internally or externally. However, comprehensive safety studies are lacking. Safety in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established.
Keep in mind that if aloe is used as a treatment for diabetes, and it proves effective, blood sugar levels could fall too low, necessitating a reduction in medication dosage. Close monitoring of blood sugar levels is, therefore, advised.
In addition, there is one report of an herb-drug interaction between aloe and the anesthesia drug sevoflurane, in which it appeared that aloe may have increased sevoflurane's "blood thinning" effect. 30
Another isolated report appears to connect aloe to liver inflammation in one person. 34 (Since aloe does not appear to possess any liver toxicity in general, this report would seem to suggest an “idiosyncratic,” in other words, a highly personal reaction to the herb.)
7. Williams MS, Burk M, Loprinzi CL, et al. Phase III double-blind evaluation of an aloe vera gel as a prophylactic agent for radiation-induced skin toxicity. Int J Radiat Oncol Biol Phys. 1996;36:345-349.
8. Bunyapraphatsara N, Yongchaiyudha S, Rungpitarangsi V, et al. Antidiabetic activity of Aloe vera L. juice II. Clinical trial in diabetes mellitus patients in combination with glibenclamide. Phytomedicine. 1996;3:245-248.
10. 't Hart LA, Nibbering PH, van den Barselaar MT, et al. Effects of low molecular weight constituents from Aloe vera gel on oxidative metabolism and cytotoxic and bactericidal activities of human neutrophils. Int J Immunopharmacol. 1990;12:427-434.
12. Kemp MC, Kahlon JB, Chinnah AD, et al. In-vitro evaluation of the antiviral effects of acemannan on the replication and pathogenesis of HIV-1 and other enveloped viruses: Modification of the processing of glycoprotein precursors [abstract]. Antiviral Res. 1990;13(suppl 1):83.
13. Syed TA, Afzal M, Ashfaq Ahmad S, et al. Management of genital herpes in men with 0.5% Aloe vera extract in a hydrophilic cream: a placebo-controlled double-blind study. J Dermatol Treat . 1997;8:99-102.
14. Syed TA, Cheema KM, Ashfaq A, et al. Aloe vera estract 0.5% in ahydrophilic cream versus Aloe vera gel for the management of genital herpes in males. A placebo-controlled, double-blind, comparative study [letter]. J Eur Acad Dermatol Venereol . 1996;7:294-295.
18. Bunyapraphatsara N, Yongchaiyudha S, Rungpitarangsi V, et al. Antidiabetic activity of Aloe vera L. juice II. Clinical trial in diabetes mellitus patients in combination with glibenclamide. Phytomedicine. 1996;3:245-248.
23. Olsen DL, Raub W Jr, Bradley C, et al. The effect of aloe vera gel/mild soap versus mild soap alone in preventing skin reactions in patients undergoing radiation therapy. Oncol Nurs Forum . 2001;28:543-547.
26. Montaner JS, Gill J, Singer J, et al. Double-blind placebo-controlled pilot trial of acemannan in advanced human immunodeficiency virus disease. J Acquir Immune Defic Syndr Hum Retrovirol . 1996;12:153-157.
27. Su CK, Mehta V, Ravikumar L, et al. Phase II double-blind randomized study comparing oral Aloe vera versus placebo to prevent radiation-related mucositis in patients with head-and-neck neoplasms. Int J Radiat Oncol Biol Phys . 2004;60:171-177.
31. Paulsen E, Korsholm L, Brandrup F, et al. A double-blind, placebo-controlled study of a commercial Aloe vera gel in the treatment of slight to moderate psoriasis vulgaris. J Eur Acad Dermatol Venereol . 2005;19:326-231.
35. Choonhakarn C, Busaracome P, Sripanidkulchai B, et al. The efficacy of aloe vera gel in the treatment of oral lichen planus: a randomized controlled trial. Br J Dermatol. 2007 Dec 11. [Epub ahead of print]
Last reviewed April 2009 by EBSCO CAM Review Board
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