Aloe vera has a long history of use as a medicinal plant, with written record going back to 1750 BC. The plant has a wide variety of uses because different parts of the plant have different medicinal properties. The mucilaginous gel that is most widely associated with aloe vera comes from the inner part of the leaf. It is separated from the pericyclic tubules, specialized cells that are under the epidermis of the leaf. Those cells have a bitter yellow latex or juice that is dried to form a pharmaceutical product called aloe latex. Aloe gel is used for wound healing, both internally and externally. It greatly speeds the healing of many skin injuries, including ulcerations, burns, frostbite, and abrasions. Aloe latex is a powerful cathartic and is used for constipation. Because it can cause painful cramping, it is not used as often as gentler herbal laxatives. Lower doses of aloe latex can be effective in preventing kidney stone formation or reducing their size. Lower doses can also be effective as a stool softener, which is particularly helpful in the case of hemorrhoids.

Aloe gel is now found in many commercial skin-care products, shampoos, and conditioners. But some studies have shown that it does not retain its healing ability when stored. There is now a stabilized form of the gel that may be able to be stored and still retain the healing action, but fresh aloe gel from the leaves is still the best option.

Aloe gel may also be taken internally, often in a liquid form called aloe juice. In this form, aloe can help heal peptic ulcers by inhibiting stomach acids that irritate ulcers. Aloe juice also improves digestion by destroying many bacteria that cause infection.

A perennial plant; yellow flowers; tough, fleshy leaves grow up to 20 inches long, 5 inches across, up to 30 per plant; grows to 4 feet. Grown in most tropical and subtropical locations, including Caribbean, southern United States, Latin America, and the Middle East.

• Leaves

Anthraquinones, aloins, anthranoids, aglycones, polysaccharides (including glycoproteins and mucopolysaccharides), and prostaglandins

Aloe gel is best fresh from an aloe plant. Slit a leaf lengthwise and remove gel. Aloe gel is also available commercially in stabilized form. Aloe latex is available as a powder or in 500 mg capsules for use as a laxative. Aloe juice is available in liquid form.

• Aloe was historically used to treat burns.
• Traditional herbal actions: antibacterial, antifungal, anesthetic, antipyretic, antipruritic, moisturizer, vasodilator, anti-inflammatory, anthelmintic, cathartic, stomachic, demulcent, emmenagogue, laxative combined with carminative, vulnerary
• Clinical applications: burns (due to radiation, sunburn, and other causes), headaches, dry skin, rashes (due to dermatitis, poison ivy, or insect bites), kidney stones, hemorrhoids, hives, constipation, wound healing, peptic ulcers, immune system enhancement, diabetes, asthma

Aloe vera contains vitamins C and E and zinc, which are all important for wound healing. Glycoproteins in aloe gel inhibit and break down bradykinin, a mediator of pain and inflammation. Aloe gel also inhibits thromboxane, which also causes inflammation. Aloe gel stimulates fibroblast and connective tissue formation, a healing action that most other anti-inflammatories don't have. The polysaccharides in aloe seem to stimulate skin growth and repair as well. Aloe also increases blood flow to burned tissue, which helps it heal.

Aloe gel has been particularly effective in healing diabetic leg ulcers because along with its other wound healing capabilities, it also lowers blood sugar.

Aloe gel's antibacterial and antifungal ability compares favorably with that of silver sulfadiazine, an antiseptic used regularly in treatment of extensive burns. Aloe vera extract has been shown to kill Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens, Citrobacter species, Enterobacter cloacae, Streptococcus pyogenes, Streptococcus agalactiae, Staphylococcus aureus, Escherichia coli, Streptococcus faecalis, and Candida albicans.

Aloe's active cathartic component is aloin. In small doses, it gives tone to intestinal muscle. In larger doses, it becomes a strong purgative, increasing colonic secretions and peristaltic contractions in the large intestine. It is harsher on the system than other anthraquinone laxatives, such as cascara and senna. The anthraquinones in aloe latex prevent kidney stone formation by binding calcium in the urinary tract and reducing the growth rate of urinary calcium crystals.

Aloe juice heals peptic ulcers by inhibiting pepsin when the stomach is empty, releasing it only to digest food. It inhibits the release of hydrochloric acid by preventing the binding of histamine to parietal cells. It also heals and prevents other irritants from reaching the ulcer. Aloe juice aids the digestive process by increasing gastric pH, reducing yeast infections, and improving water retention.

Acemannan, an antiviral compound of aloe juice, is a powerful immune system stimulant. It enhances macrophage activity, the function of T cells, and interferon production.

• The dosage for dry aloe extract is very small (50 to 200 mg).
• For general use: dosage of gel or juice 2 tbsp tid (the standardized aloe product measured to hydroxyanthracene derivatives is not widely available in the USA)
• For prevention of kidney stones: 2 to 3 tbsp daily
• For laxative purposes: 500 to 1,000 mg daily (care should be taken that laxative doses of aloe are accompanied by carminative herbs to prevent griping)
• For burns or wound healing, topically: aloe vera gel applied liberally (fresh gel from aloe plant is best)
• For hemorrhoids, as a stool softener: dry aloe extract, 0.05 to 0.2 g
• For constipation: 20 to 30 mg hydroxyanthracene derivatives per day, calculated as anydrous aloin

Aloe gel is safe for external use, unless it causes a rare allergic reaction. Discontinue use if it irritates the skin. It is not useful for treatment of deep, vertical wounds (e.g. cesarean incision). Aloe latex may cause severe intestinal cramps or diarrhea.

Pregnant or nursing mothers should not ingest aloe latex. It may cause uterine contractions and trigger miscarriage. Contraindicated for gastrointestinal illness, intestinal obstruction, appendicitis, and abdominal pain of unknown origin. May aggravate ulcers, hemorrhoids, diverticulosis, diverticulitis, colitis, and irritable bowel syndrome. If taken over a long time, can cause dependence or disturbance of electrolyte balance. May cause urine to turn a harmless red color. Should not be used for children under 12.

In a single blind clinical trial of patients with diabetes mellitus, aloe vera juice (1 tbsp 80% juice bid) combined with glyburide (10 mg glibenclamide) significantly improved blood sugar levels and decreased triglyceride levels (Bunyapraphatsara et al. 1996). Glyburide alone was ineffective. The effects of the combined treatment were not greater than results obtained from treatment with aloe vera juice alone. Blood glucose levels should be monitored carefully in diabetic patients using aloe vera either alone or in combination with other antidiabetic medications in order to avoid potential hypoglycemic complications.

The topical and systemic applications of aloe vera combined with hydrocortisone 21-acetate significantly reduced edema in mice and rats with acute inflammation (Davis et al. 1991). Topically, aloe vera (5%) and hydrocortisone (0.5% aqueous solution) decreased ear inflammation in mice by 85.6%. Systemically, aloe (25 mg/kg and 100 mg/kg) combined with hydrocortisone (0.1 mg/kg and 100 mg/kg) decreased inflammation in rats by 65.7% compared to results obtained from either treatment alone; these solutions were injected on a 10 mg/kg basis to measure the inhibitory effects on paw edema.

German Commission E approves aloe latex for chronic constipation, with certain reservations.

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