About Herbs, Botanicals & Other Products

Scientific Name
Aloe barbadensis, Aloe capensis
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Common Name

Aloe gel, aloe leaf

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Clinical Summary

Aloe vera is a tropical plant used in traditional medicine throughout the world. It has been studied for its ability to relieve constipation, heal wounds, treat psoriasis, frostbite, ulcerative colitis, diabetes, and burns. Aloe vera cream was shown to be superior to silver sulfadiazine creams for the treatment of second-degree burns (21).

Some studies suggest that some components of aloe, such as acemannan, aloeride, and di(2-ethylhexyl)phthalate (DEHP) may have immunomodulating and anticancer effects (5) (7) (8). Emodin, an extract of aloe vera, inhibited cell proliferation and induced apoptosis in human liver cancer cell lines through p53- and p21-dependent pathways (4). Aloe is also thought to have antioxidant and anti-inflammatory properties (9).
Concurrent administration of aloe with chemotherapy may prevent oral mucositis in patients receiving chemotherapy (23) and benefit those with metastatic cancers (20). More research is needed. Data on external use of aloe products to alleviate radiation-induced skin damage are inconsistent (1) (2) (3).

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Purported Uses
  • Burns
  • Cold sores
  • Colitis
  • Diabetes
  • Dry Skin
  • Inflammation
  • Pain
  • Pruritus
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Constituents
  • Mono- and polysaccharides
  • Tannins
  • Sterols
  • Organic acids
  • Enzymes
  • Saponins
  • Vitamins
  • Minerals
  • Glucomannan, acemannan
  • Emodin
  • Lipids: cholesterol, gamolenic acid
    (18) (16)
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Mechanism of Action

It is presently believed that some of the beneficial effects of aloe result from inhibition of bradykinin by a contained carboxypeptidase. Aloe is also thought to hinder the formation of thromboxane, the activity of which is detrimental to healing of burn wounds (17). Laxative effect of aloe juice and aloe latex is caused by anthraquinone glycosides aloin A and B (16). Some studies have indicated that aloe vera may have anticancer effects. Emodin, an extract of aloe vera, can inhibit cell proliferation and induce apoptosis in human liver cancer cell lines through p53- and p21-dependent pathway (4). Acemannan, a carbohydrate fraction derived from aloe vera leaf, can stimulate cytokine production in mouse macrophage cell line (5). It also exhibited immunomodulating activity by inducing maturation of dendritic cells (6). Another in vitro study has indicated aloeride, a polysaccharide obtained from aloe vera juice, as a potent immunostimulator by increasing NF-kappa B activities (7). A compound, di(2-ethylhexyl)phthalate (DEHP), isolated from aloe vera can inhibit leukemic cells in vitro (8).

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Warnings

Aloe vera gel should not be confused with aloe juice or aloe latex, both of which contain anthraquinone, a cathartic laxative. Aloe vera taken for internal use should be discouraged due to possible adverse effects and inconclusive clinical data. Aloe vera injections for cancer patients have resulted in several deaths.
The FDA rules that aloe is not safe as a stimulant laxative.
(14)

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Adverse Reactions
  • Topical administration of aloe vera gel is considered safe but oral consumption of aloe can cause gastrointestinal upset and electrolyte abnormalities.
  • Inappropriate use of aloe vera supplements has been linked to thyroid dysfunction (10), acute hepatitis (11), and perioperative bleeding (12). Parenteral administration of aloe should be avoided due to potential toxicities and lack of clinical efficacy in humans.
  • A case of hypokalemia has been reported with use of aloe vera during chemotherapy (19).
  • Three cases of toxic hepatitis were reported following use of aloe preparations. Liver function was normalized after discontinuing aloe (22).
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Herb-Drug Interactions
  • Cytochrome P450 substrates: In vitro, aloe vera juice was found to inhibit CYP3A4 and CYP2D6 and can affect the intracellular concentration of drugs metabolized by these enzymes (24).

    Oral
  • Glyburide: Aloe may increase hypoglycemic effects.
  • Diuretics: Aloe may have additive hypokalemic effect due to diarrhea if used for a prolonged period.
  • Digoxin: Aloe may have additive hypokalemic effect due to diarrhea if used for a prolonged period.

  • Topical
  • Hydrocortisone: Aloe may increase anti-inflammatory effects.
    (15)
  • Sevoflurane:Aloe may have additive antiplatelet effect causing excessive bleeding during surgery. (12)
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Literature Summary and Critique

Worthington HV, Clarkson JE, Bryan G, et al. Interventions for preventing oral mucositis for patients with cancer receiving treatment. Cochrane Database Syst Rev. 2011 Apr 13;(4):CD000978.
This review included 131 studies involving 10,514 randomised subjects. Ten interventions, where there was more than one trial, showed some statistically significant evidence of a benefit for preventing or reducing the severity of mucositis, compared to either a placebo or no treatment. The treatments were aloe vera, amifostine, cryotherapy, granulocyte-colony stimulating factor (G-CSF), intravenous glutamine, honey, keratinocyte growth factor, laser, polymixin/tobramycin/amphotericin (PTA) antibiotic pastille/paste and sucralfate.
However, the strength of evidence varied and benefits may be specific for certain cancers and treatment. Well designed trials are needed to establish the above findings.
 
Heggie S, et al. A Phase III study on the efficacy of topical aloe vera gel on irradiated breast tissue. Cancer Nurs 2002;25(6):442-51.
This is a Phase III trial involving 225 women with breast cancer who received radiation therapy after lumpectomy or partial mastectomy. Patients were randomized to receive either topical aloe vera gel or topical aqueous cream for 2 weeks after radiation treatment. The author concluded that aloe vera gel is less effective than aqueous cream in reducing radiation induced skin side effects, such as dry desquamation and pain.

Olsen DL, et al. The effect of aloe vera / mild soap versus mild soap in preventing skin reactions in patients undergoing radiation therapy. Oncol Nurs Forum 2001;28:543-7.
A randomized, blinded, prospective study of patients undergoing radiation therapy. Seventy patients were randomized to receive skin care with either aloe vera and mild soap or mild soap alone. Time to skin change (texture, erythema, tanning, pruritus) was the primary measured outcome. Aloe vera product contained pure aloe vera gel in addition to d-alpha tocopherol, triethanolamine, and methylparaben. There was no statistically significant difference between the treatment arms at low cumulative dose(<2,700 cGy). Aloe vera added soap seems to have a protective effect on patients who received a higher cumulative radiation dose(>2700 cGy).

 

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References
  1. Heggie S, Bryant GP, Tripcony L, Keller J, Rose P, Glendenning M, et al. A Phase III study on the efficacy of topical aloe vera gel on irradiated breast tissue. Cancer Nurs. 2002 Dec;25(6):442-51.
  2. Olsen DL, Raub W, Jr., Bradley C, Johnson M, Macias JL, Love V, 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 Apr;28(3):543-7.
  3. Williams MS, Burk M, Loprinzi CL, Hill M, Schomberg PJ, Nearhood K, 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 Sep 1;36(2):345-9.
  4. Kuo PL, Lin TC, Lin CC. The antiproliferative activity of aloe-emodin is through p53-dependent and p21-dependent apoptotic pathway in human hepatoma cell lines. Life Sci. 2002 Sep 6;71(16):1879-92
  5. Zhang L, Tizard IR. Activation of a mouse macrophage cell line by acemannan: the major carbohydrate fraction from Aloe vera gel. Immunopharmacology. 1996 Nov;35(2):119-28.
  6. Lee JK, Lee MK, Yun YP, Kim Y, Kim JS, Kim YS, et al. Acemannan purified from Aloe vera induces phenotypic and functional maturation of immature dendritic cells. Int Immunopharmacol. 2001 Jul;1(7):1275-84.
  7. Pugh N, Ross SA, ElSohly MA, Pasco DS. Characterization of Aloeride, a new high-molecular-weight polysaccharide from Aloe vera with potent immunostimulatory activity. J Agric Food Chem. 2001 Feb;49(2):1030-4.
  8. Lee KH, Kim JH, Lim DS, Kim CH. Anti-leukaemic and anti-mutagenic effects of di(2-ethylhexyl)phthalate isolated from Aloe vera Linne. J Pharm Pharmacol. 2000 May;52(5):593-8.
  9. Yagi A, Kabash A, Okamura N, Haraguchi H, Moustafa SM, Khalifa TI. Antioxidant, free radical scavenging and anti-inflammatory effects of aloesin derivatives in Aloe vera. Planta medica. 2002 Nov;68(11):957-60.
  10. Pigatto PD, Guzzi G. Aloe linked to thyroid dysfunction. Archives of medical research. 2005 Sep-Oct;36(5):608.
  11. Rabe C, Musch A, Schirmacher P, Kruis W, Hoffmann R. Acute hepatitis induced by an Aloe vera preparation: a case report. World J Gastroenterol. 2005 Jan 14;11(2):303-4.
  12. Lee A, Chui PT, Aun CS, Gin T, Lau AS. Possible interaction between sevoflurane and Aloe vera. Ann Pharmacother. 2004 Oct;38(10):1651-4.
  13. Anon. License revoked for aloe vera use. Nat Med Law 1998;1:1-2.
  14. FDA. Status of Certain Additional Over-the-Counter Drug Category II and III Active Ingredients. http://www.fda.gov/ohrms/dockets/98fr/050902a.htm. Accessed August 14, 2009.
  15. Brinker F. Herb Contraindications and Drug Interactions, 3rd ed. Sandy (OR): Eclectic Med; 2001.
  16. Robbers JE, et al. Pharmacognosy and pharmacobiotechnology. Baltimore: Williams & Wilkins; 1996.
  17. Foster S, et al. Tyler's Honest Herbal: A Sensible Guide to the Use of Herbs and Related Remedies. New York: Haworth Herbal Press; 1999.
  18. Tyler, V. Herbs of Choice, the Therapeutical Use of Phytomedicinals. Binghamton, New York: Pharmaceutical Press; 1994.
  19. Baretta Z, Ghiotto C, Marino D, Jirillo A. Aloe-induced hypokalemia in a patient with breast cancer during chemotherapy. Ann Oncol 2009 Aug;20(8):1445-6.
  20. Lissoni P, Rovelli F, Brivio F, et al. A randomized study of chemotherapy versus biochemotherapy with chemotherapy plus Aloe arborescens in patients with metastatic cancer. In Vivo. 2009 Jan-Feb;23(1):171-5.
  21. Khorasani G, Hosseinimehr SJ, Azadbakht M, Zamani A, Mahdavi MR. Aloe versus silver sulfadiazine creams for second-degree burns: a randomized controlled study. Surg Today. 2009;39(7):587-91.
  22. Yang HN, Kim DJ, Kim YM, et al. Aloe-induced toxic hepatitis. J Korean Med Sci. 2010 Mar;25(3):492-5.
  23.  Worthington HV, Clarkson JE, Bryan G, et al. Interventions for preventing oral mucositis for patients with cancer receiving treatment. Cochrane Database Syst Rev. 2011 Apr 13;(4):CD000978.
  24. Djuv A, Nilsen OG. Aloe Vera Juice: IC(50) and Dual Mechanistic Inhibition of CYP3A4 and CYP2D6. Phytother Res. 2011 Aug 15. doi: 10.1002/ptr.3564.
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How It Works

Bottom Line: Aloe is safe for topical use. It is not an effective cancer treatment and is dangerous when given by injection.

Scientists think that compounds found in aloe inhibit molecules that play a role in inflammation. Studies in laboratory rats confirm this anti-inflammatory activity. Aloe is also thought to hinder the formation of thromboxane, a molecule that is detrimental to the healing of burn wounds. Aloe kills bacteria and fungi directly in laboratory studies. Aloe vera gel should not be confused with aloe juice or aloe latex, both of which contain potent laxative substances.

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Purported Uses
  • As a topical anesthetic
    Laboratory evidence supports this use, but it has not been tested in clinical trials.
  • To treat burns
    Scientific evidence supports the topical use of aloe for minor burns.
  • To prevent and treat redness, rash, and pruritus caused by radiation therapy
    Clinical trials have produced conflicting results in support of and against this use. Topical use of aloe is generally safe.
  • As a skin moisturizer
    No scientific evidence supports this use.
  • To treat inflammation associated with conditions such as cold sores, eczema, and pruritis
    Clinical evidence supports this use.
  • To treat cancer
    No scientific evidence supports this use. Cancer therapy using injections of acemannan, a substance found in aloe, resulted in death of several patients.
  • To treat diabetes
    Two nonrandomized trials conducted by the same group suggest that blood glucose levels may be reduced by aloe vera. Further study is warranted.
  • To treat ulcerative colitis
    A small randomized, controlled trial shows weak support for this use. More research is needed.
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Research Evidence

Side effects associated with Cancer treatments
A review of 131 studies involving 10,514 randomised participants was conducted to determine effectiveness of agents used to prevent oral mucositis in cancer patients. Ten interventions, where there was more than one study, showed some statistically significant evidence of benefit in preventing or reducing the severity of mucositis, compared to either a placebo or no treatment. The treatments were aloe vera, amifostine, cryotherapy, granulocyte-colony stimulating factor (G-CSF), intravenous glutamine, honey, keratinocyte growth factor, laser, polymixin/tobramycin/amphotericin (PTA) antibiotic pastille/paste and sucralfate.
However, the strength of evidence varied and benefits may be specific for certain cancers and treatment. More well designed trials are needed to establish the above findings.

One study compared the use of a mild soap with or without a topical aloe vera gel in 70 patients undergoing radiation therapy for cancer. The time it took for skin changes (such as redness and itching) to develop was measured, and practically no difference was seen between patients using aloe and those using soap alone. However, patients who used aloe and received high doses of radiation (greater than 2700 cGy) did show some benefit. It should be noted that the aloe vera gel also included vitamin E and other ingredients that may have had an effect on the outcomes.

In another clinical trial, 225 women with breast cancer who received radiation therapy after lumpectomy or partial mastectomy were studied to see if aloe vera gel was better than a water-based body cream in preventing skin side effects of radiation therapy. For two weeks during radiation therapy, the women were randomly assigned to apply either aloe vera gel or the cream to the affected area. Results showed that aloe vera gel is less effective than a water-based cream in reducing radiation-induced skin side effects, such as peeling and pain.

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Patient Warnings
  • This product is regulated by the FDA as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. This product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.
  • Aloe vera gel should not be confused with aloe juice or aloe latex, both of which contain anthraquinone, a potent laxative.
  • Despite the use of some oral dosages in clinical trials of ulcerative colitis, there is not enough evidence at this time to support the use of aloe vera by mouth or by injection. The risk of serious adverse effects is high, and several cancer patients died from aloe vera injections that were used as a cancer therapy.
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Do Not Take If
  • You are taking glyburide, diuretics, or digoxin (This applies to use of aloe vera by mouth ONLY: As a laxative, oral aloe may further lower blood sugar or potassium levels if used for a long period of time).
  • If you are taking drugs that are substrates of Cytochrome P450 3A4 and CYP2D6 (Aloe vera juice may increase the risk of side effects of these drugs).
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Side Effects
  • Certain dosage forms of aloe when taken orally, can cause GI upset, nausea, vomiting, and rash.
  • Toxicity from ingestion of aloe includes seizures, dangerously low blood potassium levels, and electrolyte abnormalities.
  • A case of hypokalemia (low potassium levels) has been reported with use of aloe vera during chemotherapy.
  • Three cases of toxic hepatitis were reported following use of aloe preparations. Liver function was normalized after discontinuing aloe.
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Dosage (Inside MSKCC Only)
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Last updated: December 7, 2011