Written by Edzard Ernst and the CAM-Cancer Consortium.
Updated March 20, 2013

Aloe vera

Is it safe?

Adverse effects

Numerous adverse effects are on record but, generally speaking, these are mild and reversible2. Topical use: allergic reactions, delayed healing of deep wounds.

Oral use: irritation of and damage to intestinal mucosa, intestinal pain, diarrhoea, fluid and electrolyte loss.


Oral: pregnancy (oral administration can cause abortion), intestinal obstruction or inflammation.


Oral: increased effects of antiarrhythmics, cardiac glycosides, diuretics and steroids2.


Based on animal studies, there is a suspicion that oral use of Aloe vera might promote colonic cancer21 and that topical use might enhance the induction of skin cancer by ultraviolet light22.


Edzard Ernst, CAM-Cancer Consortium. Aloe vera [online document]. http://cam-cancer.org/The-Summaries/Herbal-products/Aloe-vera. March 20, 2013.

Document history

Fully updated and revised in March 2013 by Edzard Ernst.
Summary first published in July 2011, authored by Edzard Ernst.


  1. Ernst E, Pittler MH, Wider B, Boddy K. The Desktop Guide to Complementary and Alternative Medicine. 2nd edition. Edinburgh: Elsevier Mosby. 2006.
  2. Ulbricht C, Armstrong J, Basch E, Basch S, Dacey C, Dalton S et al. An evidence-based systematic review of Aloe vera by the Natural Standard Research Collaboration. J Herb Pharmacother 2007; 7(3-4):279-323.
  3. Cárdenas C, Quesada AR, Medina MA. Evaluation of the anti-angiogenic effect of Aloe-emodin. Cell Mol Life Sci 2006; 63(24):3083-3089.
  4. Xiao B, Guo J, Liu D, Zhang S. Aloe-emodin induces in vitro G2/M arrest and alkaline phosphatase activation in human oral cancer KB cells. Oral Oncol 2007; 43(9):905-910.
  5. Esmat AY, Tomasetto C, Rio MC. Cytotoxicity of a natural anthraquinone (Aloin) against human breast cancer cell lines with and without ErbB-2: topoisomerase IIalpha coamplification. Cancer Biol Ther 2006; 5(1):97-103.
  6. Singh RP, Dhanalakshmi S, Rao AR. Chemomodulatory action of Aloe vera on the profiles of enzymes associated with carcinogen metabolism and antioxidant status regulation in mice. Phytomed 2000; 7(3):209-219.
  7. Saini M, Goyal PK, Chaudhary G. Anti-tumor activity of Aloe vera against DMBA/croton oil-induced skin papillomagenesis in Swiss albino mice. J Environ Pathol Toxicol Oncol 2010; 29(2):127-135.
  8. Chaudhary G, Saini MR, Goyal PK. Chemopreventive potential of Aloe vera against 7,12-dimethylbenz(a)anthracene induced skin papillomagenesis in mice. Integr Cancer Ther 2007; 6(4):405-412.
  9. El-Shemy HA, Aboul-Soud MA, Nassr-Allah AA, Aboul-Enein KM, Kabash A, Yagi A. Antitumor properties and modulation of antioxidant enzymes' activity by Aloe vera leaf active principles isolated via supercritical carbon dioxide extraction. Curr Med CHem 2010; 17(2):129-138.
  10. Richardson J, Smith JE, McIntyre M, Thomas R, Pilkington K. Aloe vera for preventing radiation-induced skin reactions: a systematic literature review. Clin Oncol 2005; 17:478-484.
  11. Su CK, Mehta V, Ravikumar L, Shah R, Pinto H, Halpern J 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.
  12. Lissoni P, Giana L, Zerbini S, Trabattoni P, Rovelli F. Biotherapy with the pineal immunomodulating hormone melatonin versus melatonin plus Aloe vera in untreatable advanced solid neoplasms. Nat Immun 1998; 16:27-33.
  13. Suboj P, Babykutty S, Valiyaparambil Gopi DR, Nair RS, Srinivas P, Gopala S. Aloe emodin inhibits colon cancer cell migration/angiogenesis by downregulating MMP-2/9, RhoB and VEGF via reduced DNA binding activity of NF-kappaB. Eur J Pharm Sci 2012; 45(5):581-591.
  14. Tabolacci C, Rossi S, Lentini A, Provenzano B, Turcano L, Facchiano F et al. Aloin enhances cisplatin antineoplastic activity in B16-F10 melanoma cells by transglutaminase-induced differentiation. Amino Acids 2013; 44(1):293-300.
  15. Worthington HV, Clarkson JE, Bryan G, Furness S, Glenny AM, Littlewood A et al. Interventions for preventing oral mucositis for patients with cancer receiving treatment. Cochrane Database Syst Rev 2011;(4):CD000978.
  16. George J. To assess the effectiveness of aloe vera gel in preventing skin reactions associated with radiotherapy. Indian Journal of Palliative Care 2011; 17:91-103.
  17. Sudarshan R, Annigeri RG, Sree VG. Aloe vera in the treatment for oral submucous fibrosis - a preliminary study. J Oral Pathol Med 2012; 41(10):755-761.
  18. Lissoni P, Rovelli F, Brivio F, Zago R, Colciago M, Messina G et al. A randomized study of chemotharpy versus biochemotherapy with chemotherapy plus Aloe arborescens in patients with metastic cancer. In Vivo 2009; 23:171-176.
  19. Puataweepong P, Chanachai M, Dangprasert S, Sithatani C, Sawangsilp T, Narkwong L et al. The efficacy of oral Aloe vera juice for radiation induced mucositis in head and neck cancer patients: a double-blind placebo-controlled study. Asian Biomed 2009; 3(4):375-382.
  20. Sakai R. Epidemiologic survey on lung cancer with respect to cigarette smoking and plant diet. Jpn J Cancer Res 1989; 80(6):513-520.
  21. Yokohira M, Matsuda Y, Suzuki S, Hosokawa K, Yamakawa K, Hashimoto N et al. Equivocal colonic carcinogenicity of Aloe arborescens Miller var. natalensis berger at high-dose level in a Wistar Hannover rat 2-y study. J Food Sci 2009; 74(2):T24-30.
  22. National Toxicology Program. Photocarcinogenesis Study of Aloe vera [CAS NO. 481-72-1(Aloe-emodin)] in SKH-1 Mice (Simulated Solar Light and Topical Application Study). Natl Toxicol Program Tech Rep Ser 2010; Sep(553):1-206.