Summary

In ancient Greece and Africa the aloe plant was used to treat wounds. Today, aloe can be used to cure sunburns as well as heartburn. In the middle ages, aloe was used as a laxative, although modern medicine has found that use to be unfounded.  Aloe is also often used in skin care products.

Aloe is not to be used internally during pregnancy and breastfeeding. It should also not be given to children under 12 years old. Chronic aloe treatment on the skin may cause tissue damage. Aloe can be found in cream, capsule, and gel form.

Description

Medicinal Parts

The medicinal part of the plant is dried juice of the leaves.

Flower and Fruit

The inflorescence is forked once or twice and is 60 to 90 cm high. The raceme is dense, cylindrical and narrows toward the top. The terminal raceme is up to 40 cm high while the lower ones are somewhat shorter. The bracts are almost white, and the flowers are yellow, orange or red, and are 3 cm long.

Leaves, Stem, and Root

The lilylike succulent-leafed rosette shrub has a 25-cm stem or none at all. The stem has about 25 leaves in an upright dense rosette. The lanceolate leaf is thick and fleshy, 40 to 50 cm long and 6 to 7 cm wide at the base. The upper surface is concave, gray-green, often with a reddish tinge, which sometimes appears in patches in the young plants. The leaf margin has a pale pink edge and 2 mm long pale teeth.

Habitat

Aloe is thought to have originated in the Sudan and the Arabian Peninsula. Today the species is cultivated and found in the wild in northern Africa, the Near East, Asia, and in the southern Mediterranean region. The plant is cultivated in subtropical regions of the United States and Mexico, and on the Dutch Antilles, as well as coastal regions of Venezuela.

Production

Curacao Aloe consists of the dried latex of the leaves of Aloe barbadensis (syn. Aloe vera), as well as its preparations. Aloe is harvested from August until October. The juice is dried using various methods.

Not to be Confused With

Agave americana, known as American Aloe, which is not a true Aloe.

Actions & Pharmacology

Compounds: Aloe Barbadensis

Anthracene derivatives: particularly anthrone-10-C-glycosyls, including aloin A, aloin B, 7-hydroxyaloins A and B, and 1,8-dihydroxy ions, including Aloe-emodin, and 6′cinnamic acid esters of these compounds

2-alkylchromones: including Aloe resins B, C and D

Flavonoids

Compounds: Aloe Capensis

Anthracene derivatives: particularly anthrone-10-C-glycosyls, including aloin A, aloin B, 5-hydroxyaloin, and 1,8-dihydroxy anthraquinones, including Aloe-emodin, and mixed anthrone-C- and O-glycosides, including aloinosides A and B

2-alkylchromones: including Aloe resins A, B, C and D

Flavonoids

Effects

Antibacterial/Antiviral Effects

Aloe-emodin exerts dose-dependent growth inhibition of Heliobacter pylori through inhibition of arylamine N-acetyltransferase (NAT) activity (Wang, 1998). Aloe-emodin has shown antibacterial effects on four strains of methicillin-resistant Staphylococcus aureus (Hatano, 1999). Aloe emodin inactivates enveloped viruses and is directly viracidal to herpes simplex virus type 1 and type 2, varicella-zoster virus, pseudorabies virus, and influenza virus (Sydiskis, 1991).

Anti-inflammatory effects

The anti-inflammatory effect of the Aloe gel may be due to the salicylates, inactivation of bradykinin (via carboxypeptidases), and inhibition of histamine formation (Briggs, 1995; Natow, 1986). It appears that various nonspecified components in the gel reduce the oxidation of arachidonic acid, thereby reducing prostaglandin synthesis and inflammation (Davis et al, 1987; Pennys, 1982).

Antineoplastic Effects

Emodin suppresses tyrosine kinase activity of HER-2/neu-encoded p185neu receptor tyrosine kinase resulting in antineoplastic effects. This is beneficial in controlling HER-2/neu overexpressing cancer cells (Zhang, 1998).

Laxative (Cathartic) Effects

Anthraquinones such as Aloe are colonic-specific stimulant laxatives that have a direct action on intestinal mucosa, increasing the rate of colonic motility, enhancing colonic transit time, and inhibiting water and electrolyte secretion (Klinik et al, 1993; Godding, 1988). In addition, the laxative effect is due to irritation and stimulation of the colon. Other ingredients include Aloe-emodin, Aloesin, Aloetic acid, anthracene, anthranol, barbaloin, beta-or isobarbaloin, chrysophanic acid, cinnamic acid ester, emodin, an ethereal oil, resins (resistannol), and saponins (Shelton, 1991; Holdsworth, 1971; McCarthy & Haynes, 1967). There is some evidence that endogenous nitric oxide modulates the diarrhea effect of Aloe. Studies demonstrate a laxative effect 9 hours after ingestion (Izzo, 1999).

Anthraquinones may also have stool softening properties and do not disrupt the usual pattern of defecation (Gilman et al, 1990; Godding, 1988). The onset of action may be in 6 to 12 hours, or delayed for up to 24 hours (Koch, 1993; Cohen, 1992). Aloe vera latex, the pericyclic cells of the leaf produce a bitter yellow latex which is dried to give a dark brown solid material called “ALOEs” in many older pharmacy texts. This material is a strong cathartic containing various anthraquinones usually designated as aloin, which is primarily 1,8-dihyroxy-3-(hydroymethyl)-p,10-anthracenedione (Briggs, 1995).

A partial purification (via ethanolic and aqueous extracts) of Aloe vera leaves was strongly antibacterial and inhibited the growth of Bacillus subtilis. The action of the antibiotic substance was thought to be inhibition of nucleic acid synthesis and subsequent protein synthesis (Levin et al, 1988).

The sugar and polysaccharide content of the Aloe gel may be antibiotic via osmotic inhibition of bacterial growth. An antibacterial action is still under investigation and studies may find there is no effect (Briggs, 1995).

Effects of Topical Aloe Plants

Aloe vera depresses potential generation and conduction at neuromuscular junction processes, which result in analgesic and anti-inflammatory effects (Friedman, 1999). Ultraviolet radiation (UV) suppresses delayed type hypersensitivity (DTH) by altering the function of immune cells in the skin and causing the release of immunoregulatory cytokines. Extracts of crude Aloe barbadensis gel inhibits this photosuppression by preventing suppression of DTH responses and reducing the amount of keratinocyte derived immunosuppressive cytokines (IL-2) (Byeon, 1998; Strickland, 1999). Aloe vera gel contains small molecular modulators that prevent UVB-induced immune suppression in the skin. The immunomodulators restore the UVB-induced damages on epidermal Langerham cells (Lee, 1999).

Aloe vera increases collagen content of the granulation tissue and its degree of crosslinking to contribute to wound healing (Chithra, 1998). Aloe vera acts as a modulatory system toward wounds with anti-inflammatory effects (Davis, 1991). The use of Aloe vera has been associated with a delay in wound healing compared to standard treatment (Schmidt, 1991). Aloe vera gel exerts anti-inflammatory activity through its inhibitory action on the arachidonic acid pathway via cyclooxygenase (Vazquez, 1996). Due to its anti-thromboxane effects, Aloe vera decreases the morbidity of progressive dermal ischemia in frostbite (Heggers, 1987). Aloe vera contains a carboxypeptidase that inactivates bradykinin, salicylates, and a substance that inhibits thromboxane formation (Fujita, 1976; Klein, 1988).

The exact mechanism for the wound healing abilities of Aloe is uncertain, but probably involves an anti-inflammatory effect involving consumption of complement 3, depletion of classical and alternative pathway complement activity, inhibition of free oxygen radicals by activating polymorphonuclear leucocytes, thromboxane inhibition, and bradykinin inhibition (Hart et al, 1989; Hart et al, 1988; Zachary et al, 1987)

Clinical Trials

Acne

A study involving Aloe vera preparations for acne was discussed in a larger review considering the empirical evidence for complementary and alternative treatments (topical and oral) for acne. While Aloe vera gel alone was only minimally effective in anti-acne activity, in one randomized controlled trial cited (n=84), its combination with Ocimum oil appeared to be synergistic—even more effective than the application of a standard acne prescription formula of 1% clindamycin. The study showed that the effectiveness of various concentrations of Aloe vera gel with and without Ocimum gratissimum oil (topical) were significantly better than placebo in reducing the number of acne lesions (Magin, 2006).

Constipation

A preparation containing celandin, Aloe vera, and psyllium produced more frequent bowel movements, softer stools, and less laxative dependence than controls in a double-blind, randomized, placebo-controlled study of 35 patients with chronic constipation. Symptoms during the last 2 weeks of this 28-day trial were compared with baseline figures obtained during the 2 weeks prior to the study initiation. Abdominal pain was not reduced in either group. A capsule of the preparation was given each day at the beginning of the study and, depending on response, was increased to 3 capsules during the study in some participants. Each capsule was 500 mg and consisted of celandin, Aloe vera, and psyllium in a 6:3:1 ratio. The part of the Aloe plant used was not mentioned. The preparations were not evaluated separately, only as the mixture. (Odes & Madar, 1991).

Herpes Simplex

Aloe vera whole leaf extract (0.5%) in hydrophilic cream (4.8 days) showed a statistically shorter mean duration of healing sores of genital herpes compared to Aloe vera gel (7 days) or placebo (14 days). The percentage of healed patients increased in the Aloe group as well (70%, 45%, and 7.5%, respectively). There were 120 male circumcised patients with their first episode of genital herpes and no previous history of herpes generalis. The subjects had a total of 1,496 lesions (mean of 12.5) that were present for less than 7 days (mean 4.3 days). Patients (n=120) were divided into three groups, one treated with the Aloe-containing cream, one with Aloe gel, the other a placebo cream. Application was 3 times a day with a protected finger, for 5 consecutive days per week for 2 weeks. Aloe vera extract and gel were both effective in reducing healing and duration of lesions, but Aloe vera in the cream form was statistically better in reducing mean lesion duration and healing compared to either the gel or the placebo. There were no significant side effects (Syed et al, 1996).

Aloe vera whole leaf extract (0.55) was found to be effective in treating first lesions of herpes simplex in 60 men with culture-confirmed herpes simplex genitalis who had lesions within 7 days of initial outbreak. The total number of lesions in the group was 738 (mean 12.3). Patients were randomly assigned to a placebo group and the same cream with aloe added. The cream was self-applied three times daily for 5 consecutive days for 3 weeks. Patients were examined twice weekly, and reepithelialized lesions with some residual erythema were considered “cured.” The Aloe extract group had a significantly shorter mean time to healing than placebo (4.9 days as compared to 12 days) (p<0.001). There was also a 66.7% rate of healed patients in the aloe group, while only a 6.7% rate in the placebo group (p<0.001). There were 5 cases of mild itching that resolved in the first 24 hours; this did not result in patient withdrawal. “Cured” patients were followed for 20 months, and at the end of this time there was a 13% recurrence rate (Syed et al, 1997).

Irritable Bowel Syndrome

Fifty-eight patients with irritable bowel syndrome (IBS) were randomized to receive Aloe vera or a placebo during a 3-month period. Symptoms were assessed at baseline, 1 and 3 months. No evidence was found that Aloe vera benefits patients with IBS (Davis et al, 2006).

Psoriasis

Forty-one patients with stable plaque psoriasis took part in a randomized, double-blind, placebo-controlled right/left comparison study to test the effect of a commercial, preserved but otherwise untreated, Aloe vera gel. A 2-week wash-out period was followed by a 4-week treatment period with 2 daily applications and follow-up visits after 1 and 2 months. The score sum of erythema, infiltration, and desquamation decreased in 72.5% of Aloe vera-treated sites compared with 82% of placebo-treated areas from week 0 to week 4. The results indicate that the effect of the commercial Aloe vera gel on stable plaque psoriasis was modest and not better than placebo (Paulsen et al, 2005).

An earlier study shows, however, that Aloe vera (0.5%) whole leaf extract effectively (p<0.001) cured or reduced the signs of psoriasis in a double-blind, placebo-controlled study. Sixty patients with slight to moderate chronic plaque-type psoriasis were randomized into 2 groups, 1 using a placebo cream, the other using the cream with Aloe vera extract (with mineral oil and castor oil to solubilize the Aloe). The mean Psoriasis Area and Severity Index (PASI) score before treatment was 9.3 (range 4.8 to 16.7). Patients applied the creams topically, without occlusion or exposure to sunlight, to affected areas 3 times a day for 5 consecutive days per week for 4 weeks. Patients were examined weekly, for up to 16 weeks, for reduction of lesions, desquamation, decreased erythema, infiltration, and lowered PASI scores. Results showed that 83.3% of the patients had reduced or no psoriasis signs with Aloe, while only 6.6% of controls had a positive effect. Plaque was reduced by 82.8% for the Aloe group and only 7.7% for the control group (p<0.001). The PASI score in the treated group dropped to a mean of 2.2 (Syed et al, 1996).

Radiation-Induced Skin Toxicity

A phase III, double-blind, placebo-controlled study evaluated Aloe vera gel for use as a prophylactic agent for radiation-induced skin toxicity. A total of 194 women receiving breast or chest-wall irradiation were included in the study. Skin dermatitis was scored weekly during the trial by patients and by healthcare providers. Aloe vera gel did not protect against radiation therapy-induced dermatitis (Williams, 1996).

A double-blind, placebo-controlled study with 108 breast cancer patients that were treated with a minimum 50cGy radiation dose to the breast or chest wall were evaluated for dermatitis scores following the use of topical Aloe vera. Patients were stratified based on age, breast surgery, planned target radiation dose, and skin complexion, then randomized to a control group of no treatment or an Aloe vera treated (98% Aloe) group. The medications were applied to the treatment field twice daily starting within 3 days of radiation initiation. If radiation-induced dermatitis occurred, patients were instructed to apply a 1% hydrocortisone cream at least one hour either side of the Aloe or placebo application. The chest-wall skin was evaluated weekly by a physician or nurse, and the patients graded the skin reaction weekly via a questionnaire. Measures used to assess treatment efficacy included maximum reported severity of dermatitis, time to occurrence of severe (Grade 3 or greater) dermatitis, and duration of severe dermatitis. Treatment continued through the radiation therapy. The study reported no difference between the Aloe vera group and the group treated with placebo with respect to any of the assessments measured. (Williams et al, 1996).

In a literature review of novel approaches to radiotherapy-induced skin reactions, the authors cite research by the previous study author (Williams, 1996) and others, including data from a follow-up trial. In the study reviewed, the effects of Aloe vera gel plus mild soap versus mild soap alone as a means of preventing radiotherapy-induced dermatitis were assessed in a randomized controlled trial of 70 patients. The Aloe vera gel also included urea, vitamin E, preservatives, and a filler. Skin condition was evaluated weekly. There were no adverse effects from the use of Aloe vera gel, and its application was successful in preventing radio-dermatitis in some cases, particularly in patients who received relatively higher radiotherapy doses; the reaction was less severe and skin changes took longer to develop (Maddocks-Jennings, 2005).

In contrast, the authors of a systematic review and critical appraisal of evidence (including a previous systematic review, five randomized controlled trials, and two non-published randomized controlled trials) for the effectiveness of Aloe vera gel for radiation-induced skin reactions concluded that there is no evidence to indicate that topical Aloe vera preparations are effective in preventing or lessening these lesions (Richardson 2005).

No statistically significant difference was detected between treatment with Aloe vera and placebo for mild or moderate/severe mouth ulcers (mucositis) caused by radiation or chemotherapy for cancer in 58 subjects enrolled in a trial. The Aloe vera trial had been identified by authors of a larger review of interventions for preventing this common complication in people undergoing cancer treatment (Worthington 2007).

Radiotherapy Adjunct

A phase II, double-blind, prospective, randomized, placebo-controlled trial determined that Aloe vera gel was not a beneficial adjunct to head-and-neck radiotherapy. Patients (n=58) received biweekly examinations. At the end of treatment, it was shown that subjects taking Aloe vera had identical scores to those on placebo with regard to maximal grade of toxicity, duration of Grade 2 or worse mucositis, quality-of-life scores, percentage of weight loss, use of pain medications, hydration requirement, oral infections, and prolonged radiation breaks (Su et al, 2004).

Ulcerative Colitis

To investigate the efficacy and safety of Aloe vera gel for the treatment of mildly to moderately active ulcerative colitis, a double-blind, randomized, placebo-controlled trial was performed. Subjects (n=44) were given Aloe vera gel or placebo, 100 mL twice daily for 4 weeks, in a 2:1 ratio. Primary outcome measures were clinical remission, sigmoidoscopic remission, and histological remission. The results indicate that Aloe vera produced a clinical response more often than placebo, safely reducing the histological disease activity (Langmead et al, 2004).

Ulcers, Leg

Aloe vera gel was effective in healing long-term leg ulcers that other therapies had not been able to heal. Aloe vera gel was prepared from the fresh leaves and was applied locally (via an Aloe soaked gauze) to leg ulcers 3 to 5 times daily as a dressing after the wound had been cleansed with boric acid, hydrogen peroxide, and citrimide 1% solution (El Zawahry et al, 1973). There were no control ulcers, nor means of addressing the effect of Aloe separate from that of the wound cleansings.

Ulcers, Pressure

A review of wound cleansing options for care of pressure ulcers overall identified very little rigorous research (randomized and controlled trials). One study of reasonable quality included Aloe vera, however. The study of 126 subjects followed for 14 days showed statistically significant improvement in Pressure Sore Status tool scores (percentage reduction in pressure sore status) for wounds cleansed with a saline spray combination of Aloe vera, silver chloride, and decyl glucoside (Vulnopur), compared to wounds cleansed with isotonic saline (p=0.025) (Moore, 2007).

UV Light Damage

UVB light exposure was given to 12 volunteers for 1.5 minutes using an UVB light pen (250 to 450 nanometers light spectrum). Patients between 21 and 54 years of age had no peripheral vascular disease. Four sites (two on each arm) were irradiated, two sites on one arm and a nonirradiated control site were given topical aloe gel (directly from the plant leaf) application each hour. Measurement of blood flow were taken at these sites at 6 and 24 hours. Erythema was evaluated as either greater to, equal to, or less than that in the control area. There was no significant difference in blood flow between control sites and aloe gel treated sites exposed to ultraviolet light. This was true at 6 and 24 hours post-exposure. There was no qualitative difference in erythema. (Crowell et al, 1989).

Treatment of a dermabrasion with an Aloe gel resulted in accelerated healing by about 72 hours in one study (Fulton, 1990). Eighteen full-faced dermabrasions were performed and one-half of each face treated with the standard polyethylene oxide dressing (PEOD), the other side with the dressing saturated with Aloe vera gel. Within 24 to 48 hours the Aloe side showed considerable vasoconstriction and reduction in edema. By the third to fourth day the Aloe side had less crusting and exudate, and by the fifth and sixth day reepithelialization was almost complete (90%), while the PEOD site was only 40% to 50% complete. There was a slight stinging or burning sensation when the Aloe dressing was applied, but overall, there was less pain and throbbing.

Vitamin Absorption

Aloe vera preparations increased the absorption of vitamins C (water-soluble) and E (fat-soluble) in a randomized placebo-controlled double-blind crossover study involving 11 healthy individuals ranging in age from age 21 to 42. None were taking vitamin supplements. Both aloe preparations—a whole-leaf extract and an inner fillet gel—slowed the absorption and increased the duration of the vitamins in the subjects' plasma, with maximum concentrations 2 to 4 hours later than occurred in the control group. The Aloe gel extract was particularly effective in these regard to vitamin C (ascorbate) absorption after 8 and 24 hours (Vinson, 2005).

Wound Healing

Twenty-seven patients with a recent partial thickness burn injury and an individual confluent area of more than 2%, and no previous treatment, were treated with Aloe gel/gauze and found to have an improved healing rate versus controls that received petroleum jelly/gauze dressings. Cleaned wounds were divided into two parts, the first treated with either a transparent Aloe vera gel (85% Aloe gel with another unnamed ingredients), the second part with petroleum jelly. The materials were applied twice daily, topically, with a sterile glove. Wounds were inspected and photographed on day 1, 7, 14, 21, or until complete epithelialization. By the 14th day, most of the Aloe gel treated burn areas were completely healed. The mean healing time for the Aloe gel group was 11.89 days, the time for the petroleum jelly group was 18.18 days (p<0.002). Histology of the wounds via biopsy was done on days 1, 7, 14, and 21. On day 7 the ulcerated part of both treatment areas were covered with necrotic tissue debris and red blood cells, the petroleum jelly-treated sites also had an acute inflammatory exudate intermixed with necrotic tissue. Papillary and reticular dermis was infiltrated by acute and chronic inflammatory cells. Aloe-treated areas had full epithelialization developed by 14 days with newly formed squamous epithelium. On day 14, the petroleum jelly gauze areas had partially developed epithelialization at the wound edges (Visuthikosol et al, 1995).

Aloe vera gel produced a retardation in healing using a standard wound care protocol, with and without Aloe vera gel, in 21 women who had wound complications requiring additional healing after Cesarean delivery or laparotomy. Wounds treated with the standard protocol alone healed in 53 days (standard deviation of 24 days), while those treated with Aloe vera required 83 days (standard deviation of 28 days) (p=0.003). Patients were randomly assigned, and any with diabetes, cancer, or treatments requiring corticosteroids were excluded from the study. Incisions included in the study had opened spontaneously or had been drained to treat seroma, hematoma, or wound abscesses. The Aloe gel used was a commercial product (Carrington Dermal Wound Gel) and it was applied with a gloved finger, at each dressing change, to the granulation tissue in the wound bed at the level of the subcutaneous tissue and dermis (Schimidt & Greenspoon, 1991). The study was not performed on the original, non-complicated incisions, just on incisional cases with complications.

Indications & Usage

Aloe Barbadensis and Capensis

Approved by Commission E:

• Constipation

Aloe Barbadensis

Unproven Uses

The drug is used for evacuation relief in the presence of anal fissures after recto-anal operations. In European folk medicine the drug is employed for its ability to influence digestion.

Chinese Medicine

The most common use in Chinese medicine is for treatment of fungal diseases.

Indian Medicine

Uses in Indian medicine include stomach tumors, constipation, colic, skin diseases, amenorrhea, worm infestation, and infections.

Aloe Capensis

Unproven Uses: Aloe capensis

has been used as a stool softener in the presence of anal fissures, hemorrhoids, and after recto-anal operations. The fresh juice is used for eye inflammations and for syphillis in South Africa.

Homeopathic Uses

The herb is used for gastrointestinal disorders, hemorrhoids, and constipation.

Contraindications

Aloe is contraindicated in cases of intestinal obstruction, acutely inflamed intestinal diseases (eg, Crohn's disease, ulcerative colitis), ileus of any kind (acute surgical abdomen, bowel obstruction, fecal impaction), appendicitis, and abdominal pain of unknown origin.

Pregnancy

Not to be used during pregnancy.

Breastfeeding

Not to be used while breastfeeding.

Pediatrics

Not to be given to children under 12 years of age.

Precautions & Adverse Reactions

Spasmodic gastrointestinal complaints are a side effect to the drug's purgative effect. Arrhythmias, nephropathies, edema, and accelerated bone deterioration may occur in rare cases. Prolonged use of Aloe may lead to pigmentation in the intestinal mucosa (pseudomelanosis coli), a side effect that usually reverses upon discontinuation of the drug. Long-term use can also lead to albuminuria and hematuria. Hypersensitivity, manifested by generalized nummular eczematous and papular dermatitis, has been reported after long-term use of oral and topical Aloe preparations. Contact dermatitis to Aloe gel may be due to irritation of the skin by needlelike crystals. Use of the latex containing anthraquinones may result in absorption of these chemicals resulting in a brown discoloration of body fluids.

Effects on Plasma Electrolytes

Prolonged use of excessive laxative doses may lead to significant loss of electrolytes, in particular potassium, and electrolyte/fluid imbalance may occur. Potassium loss is partly due to direct loss in the feces and partly as secondary renal effect associated with sodium loss (Westendorff, 1993). Patients taking Aloe for more than 1-2 weeks may experience hypokalemia (signs and symptoms include lethargy, muscle cramps, headaches, paresthesias, tetany, peripheral edema, polyuria, breathlessness, and hypertension). The loss of potassium can result in hyperaldosteronism, inhibition of intestinal motility and enhancement of the effect of cardioactive medications. Prolonged use should be avoided (Bisset, 1994).

Gastrointestinal

Abdominal pain, excessive bowel activities, such as diarrhea, nausea, and perianal irritation are the primary adverse effects with anthraquinone laxatives such as Aloe (Bisset, 1994). Long-term laxative use may also include bloody diarrhea and, in toxic doses, possible kidney damage. Hemorrhoids may be exacerbated by taking the latex laxative orally (Briggs, 1995).

Malignancy

Prolonged use of anthracene drugs increases the relative risk of colon carcinoma (Siegers, 1993). Recent studies failed to demonstrate a connection between the administration of anthracene drugs and frequency of carcinomas in the colon (Schorkhuber, 1998). Low molecular weight compounds found in Aloe vera gel are cytotoxic (Avila, 1997). The component 1,8-dihydroxyanthraquinone inhibits the catalytic activity of topoisomerase II resulting in genotoxicity and mutagenicity (Mueller, 1999).

Tissue Damage

Chronic treatment with high doses of Aloe reduces vasoactive intestinal peptide and somatostatin levels, which may damage enteric nervous tissue (Tzavella, 1995).

Teratogenicity

Aloe latex contains anthraquinones that may stimulate uterine muscle activity, initiate premature labor, or possibly cause abortion when given orally. Mutagenic activity to lectins that are found in Aloe have been noted (Suzuki et al, 1979). A lectin found in whole Aloe arborescens leaves was shown to have mitogenic activity on lymphocytes (Suzuki et al, 1979).

Drug Interactions

Moderate Risk

Antidiabetic Agents

Increased risk of hypoglycemia. Clinical Management: Monitor blood glucose levels and signs and symptoms of hypoglycemia closely if Aloe and an antidiabetic agent are taken together.

Digoxin

Concurrent use may result in hypokalemia resulting in digoxin toxicity. Clinical Management: Patients who are taking digoxin should be advised to avoid concomitant use with Aloe. If digoxin toxicity occurs, potassium should be monitored and supplemented if necessary while discontinuing Aloe.

Dosage

Mode of Administration

Due to the side effects of the drug, it is rarely used internally and is not recommended. Aloe powder, aqueous- and aqueous-alcoholic extracts in powdered or liquid form are available for oral use.

How Supplied

• Capsules–250 mg, 470 mg
• Cream
• Gel–99%, 72%
• Softgel–1000 mg

Preparation

A stabilized Aloe extract is prepared with hot water. The extract will have a content of 19% to 21% aloin.

Daily Dosage

The recommended daily dosage is 20 to 30 mg hydroxyanthracene derivatives/day, calculated as anhydrous aloin. The recommended single dosage is 0.05 g Aloe powder from Aloe barbadensis or 0.05 to 0.2 g Aloe powder of Aloe capensis in the evening. Aloe capensis can be given as a single dose of 0.1 g in the evening.

Homeopathic Dosage

For Aloe capensis, administer 5 drops, 1 tablet, 10 globules, or parenterally 1 to 2 mL three times daily (HAB1).

Note

The smallest dosage needed to maintain a soft stool should be used. Stimulating laxatives must not be used over an extended period of time (1 to 2 weeks) without medical advice.

Storage

Aloe should be protected from light and moisture.

Literature