Synonyms
Aloe barbadensis Mill., Aloe chinensis Bak., A. elongata Murray, A. indica Royle, A. officinalis Forsk., A. perfoliata L., A. rubescens DC, A. vera L. var. littoralis König ex Bak., A. vera L. var. chinensis Berger, A. vulgaris Lam. In most formularies and reference books, Aloe barbadensis Mill. is regarded as the correct species name, and Aloe vera (L.) Burm. f. is considered a synonym. However, according to the International Rules of Botanical Nomenclature, Aloe vera (L.) Burm. f. is the legitimate name for this species. The genus Aloe has also been placed taxonomically in a family called Aloeaceae.

Local names
Aloe capensis, aloe curacao, aloe vera, aloes, aloès, aloès du Cape, aloès fèroce, aloes vrai, aloès vulgaire, alovis, Barbadoes aloe, Barbadoes aloes, Barbados aloe, Bergaalwyn, Bitteraalwyn, Cape aloe, chirukattali, Curacao aloe, Curacao aloes, Curacao alos, Echte Aloe, ghai kunwar, ghai kunwrar, gheekuar, ghikanvar, ghikuar, ghikumar, ghikumari, ghikwar, ghiu kumari, ghrita kumari, ghritakumari, grahakanya, gwar-patha, haang takhe, hlaba, Indian aloe, jadam, korphad, kumari, kumaro, kunvar pata, kunwar, laloi, laluwe, lo-hoei, lo-hoi, lou-houey, lu wei, luchuy, manjikattali, Mediterranean aloe, murr sbarr, musabar, rokai, sabbara, saber, sábila, sabilla, sabr, saibr, savila, savilla, semper vivum, shubiri, sibr, siang-tan, star cactus, tuna, umhlaba, waan haang charakhe, wan-hangchorakhe, yaa dam, yadam, zábila, zambila

Description
Succulent, almost sessile perennial herb; leaves 30–50cm long and 10cm broad at the base; colour pea-green (when young spotted with white); bright yellow tubular flowers 25–35cm in length arranged in a slender loose spike; stamens frequently project beyond the perianth tube.

Plant material used
Dried juice. Solidified juice originating in the cells of the pericycle and adjacent leaf parenchyma, and flowing spontaneously from the cut leaf, allowed to dry with or without the aid of heat. It is not to be confused with Aloe Vera Gel, which is the colourless mucilaginous gel obtained from the parenchymatous cells in the leaves of Aloe vera (L.) Burm. f.

Major chemical constituents
Aloe contains as its major and active principles hydroxyanthrone derivatives, mainly of the aloe-emodin-anthrone 10-C-glucoside type. The major constituent is known as barbaloin (aloin) (15–40%). It also contains hydroxyaloin (about 3%). Barbaloin (=aloin) is in fact a mixture of aloin A (10S) and B (10R). A. ferox also contains aloinoside A and B. Aloin A and B interconvert through the anthranol form as do aloinoside A and B

Dosage forms
Powdered, dried juice and preparations thereof for oral use.
The correct individual dose is the smallest amount required to produce a soft-formed stool. As a laxative for adults and children over 10 years old, 0.04–0.11 g (Curacao or Barbados Aloe) or 0.06–0.17 g (Cape Aloe) of the dried juice, corresponding to 10–30mg hydroxyanthraquinones per day, or 0.1 g as a single dose in the evening.

Medicinal uses
Uses supported by clinical data
Short-term treatment of occasional constipation.

Uses described in pharmacopoeias and well established documents
None.

Contraindications
As with other stimulant laxatives, products containing Aloe should not be used in patients with intestinal obstruction or stenosis, atony, severe dehydration with electrolyte depletion, or chronic constipation. Aloe should not beadministered to patients with inflammatory intestinal diseases, such as appendicitis, Crohn disease, ulcerative colitis, irritable bowel syndrome, or diverticulitis, or to children under 10 years of age. Aloe should not be used during pregnancy or lactation except under medical supervision after evaluating benefits and risks. Aloe is also contraindicated in patients with cramps, colic, haemorrhoids, nephritis, or any undiagnosed abdominal symptoms such as pain, nausea, or vomiting.

Warnings
Aloe-containing products should be used only if no effect can be obtained through a change of diet or use of bulk-forming products. Stimulant laxative products should not be used when abdominal pain, nausea, or vomiting are present. Rectal bleeding or failure to have a bowel movement within 24 hours after use of a laxative may indicate a serious condition. Chronic use may cause dependence and need for increased dosages, disturbances of water and electrolyte balance (e.g. hypokalaemia), and an atonic colon with impaired function. The use of stimulant laxatives for more than 2 weeks requires medical supervision. Chronic abuse with diarrhoea and consequent fluid and electrolyte losses (mainly hypokalaemia) may cause albuminuria and haematuria, and may result in cardiac and neuromuscular dysfunction, the latter particularly in the case of concomitant use of cardiac glycosides (digoxin), diuretics, corticosteroids, or liquorice root

Precautions
General
Laxatives containing anthraquinone glycosides should not be used continuously for longer than 1–2 weeks, owing to the danger of electrolyte imbalance.

Drug interactions
Decreased intestinal transit time may reduce absorption of orally administered drugs. Existing hypokalaemia resulting from long-term laxative abuse can potentiate the effects of cardiotonic glycosides (digitalis, strophanthus) and antiarrhythmic drugs such as quinidine. The induction of hypokalaemia by drugs such as thiazide diuretics, adrenocorticosteroids, and liquorice root may be enhanced, and electrolyte imbalance may be aggravated.

Drug and laboratory test interactions
Standard methods may not detect anthranoid metabolites, so measurements of faecal excretion may not be reliable. Urinary excretion of certain anthranoid metabolites may discolour the urine, which is not clinically relevant but which may cause false positive results for urinary urobilinogen, and for estrogens when measured by the Kober procedure.

Carcinogenesis, mutagenesis, impairment of fertility
Data on the carcinogenicity of Aloe are not available. While chronic abuse of anthranoid-containing laxatives was hypothesized to play a role in colorectal cancer, no causal relationship between anthranoid laxative abuse and colorectal cancer has been demonstrated. In vitro (gene mutation and chromosome aberration tests) and in vivo (micronucleus test in murine bone marrow) genotoxicity studies, as well as human and animal pharmacokinetic data, indicate no genotoxic risk from Cape Aloe

Pregnancy: teratogenic effects
No teratogenic or fetotoxic effects were seen in rats after oral treatment with aloe extract (up to 1000 mg/kg) or aloin A (up to 200 mg/kg).

Pregnancy: non-teratogenic effects
Aloe should not be used during pregnancy except under medical supervision after benefits and risks have been evaluated.

Nursing mothers
Anthranoid metabolites appear in breast milk. Aloe should not be used during lactation except under medical supervision, as there are insufficient data available to assess the potential for pharmacological effects in the breast-fed infant.

Paediatric use
Oral use of Aloe in children under 10 years old is contraindicated.

Adverse reactions
Abdominal spasms and pain may occur after even a single dose. Overdose can lead to colicky abdominal spasms and pain, as well as the formation of thin, watery stools.
Chronic abuse of anthraquinone stimulant laxatives can lead to hepatitis.
Long-term laxative abuse may lead to electrolyte disturbances (hypokalaemia, hypocalcaemia), metabolic acidosis, malabsorption, weight loss, albuminuria, and haematuria. Weakness and orthostatic hypotension may be exacerbated in elderly patients when stimulant laxatives are repeatedly used. Secondary aldosteronism may occur owing to renal tubular damage after aggravated use. Steatorrhoea and protein-losing gastroenteropathy with hypoalbuminaemia have also been observed, as have excessive excretion of calcium in the stools and osteomalacia of the vertebral column. Melanotic pigmentation of the colonic mucosa (pseudomelanosis coli) has been observed in individuals taking anthraquinone laxatives for extended time periods. The pigmentation is clinically harmless and usually reversible within 4 to 12 months after the drug is discontinued. Conflicting data exist on other toxic effects such as intestinal-neuronal damage after long-term use.

Posology
The correct individual dose is the smallest amount required to produce a soft-formed stool. As a laxative for adults and children over 10 years old, 0.04–0.11 g (Curacao or Barbados Aloe) or 0.06–0.17 g (Cape Aloe) of the dried juice, corresponding to 10–30mg hydroxyanthraquinones per day, or 0.1 g as a single dose in the evening.

Plant material used
Liquid gel from the fresh leaf. Aloe Vera Gel is not to be confused with the juice, which is the bitter yellow exudate originating from the bundle sheath cells of the leaf. The drug Aloe consists of the dried juice,

Dosage forms
The clear mucilaginous gel. At present no commercial preparation has been proved to be stable. Because many of the active ingredients in the gel appear to deteriorate on storage, the use of fresh gel is recommended. Preparation of freshgel: harvest leaves and wash them with water and a mild chlorine solution. Remove the outer layers of the leaf including the pericyclic cells, leaving a “fillet” of gel. Care should be taken not to tear the green rind which can contaminate the fillet with leaf exudate. The gel may be stabilized by pasteurization at 75–80°C for less than 3 minutes. Higher temperatures held for longer times may alter the chemical composition of the gel

Chemical assays
Carbohydrates (0.3%) (12), water (98.5%). Polysaccharide composition analysis by gas–liquid chromatography

Major chemical constituents
Aloe Vera Gel consists primarily of water and polysaccharides (pectins, hemicelluloses, glucomannan, acemannan, and mannose derivatives). It also contains amino acids, lipids, sterols (lupeol, campesterol, and β-sitosterol), tannins, and enzymes. Mannose 6-phosphate is a major sugar component

Medicinal uses
Uses supported by clinical data
None.

Uses described in pharmacopoeias and well established documents
Aloe Vera Gel is widely used for the external treatment of minor wounds and inflammatory skin disorders. The gel is used in the treatment of minor skin irritations, including burns, bruises, and abrasions. The gelis further used in the cosmetics industry as a hydrating ingredient in liquids, creams, sun lotions, shaving creams, lip balms, healing ointments, and face packs. Aloe Vera Gel has been traditionally used as a natural remedy for burns. Aloe Vera Gel has been effectively used in the treatment of first- and second-degree thermal burns and radiation burns. Both thermal and radiation
burns healed faster with less necrosis when treated with preparations containing Aloe Vera Gel. In most cases the gel must be freshly prepared because of its sensitivity to enzymatic, oxidative, or microbial degradation. Aloe Vera Gel is not approved as an internal medication, and internal administration of the gel has not been shown to exert any consistent therapeutic effect.

Uses described in traditional medicine
The treatment of acne, haemorrhoids, psoriasis, anaemia, glaucoma, petit ulcer, tuberculosis, blindness, seborrhoeic dermatitis, and fungal infections

Proven pharmacological activity
Animal studies
Wound healing, Anti-inflammation

Human studies
Wound healing, Anti-inflammation

Contraindications
Aloe Vera Gel is contraindicated in cases of known allergy to plants in the Liliaceae.

Warnings
No information available.

Precautions
No information available concerning general precautions, or precautions dealing with carcinogenesis, mutagenesis, impairment of fertility; drug and laboratory test interactions; drug interactions; nursing mothers; paediatric use; or teratogenic or non-teratogenic effects on pregnancy.

Adverse reactions
There have been a few reports of contact dermatitis and burning skin sensations following topical applications of Aloe Vera Gel to dermabraded skin. These reactions appeared to be associated with anthraquinone contaminants in this preparation. A case of disseminated dermatitis has been reported following application of Aloe Vera Gel to a patient with stasis dermatitis. An acute bullous allergic reaction and contact urticaria have also been reported to result from the use of Aloe Vera Gel

Posology
Fresh gel or preparations containing 10–70% fresh gel.