The aloe plant originally came from Africa. The leaves, which are long, green, fleshy, and have spikes along the edges, are used medicinally. The fresh leaf gel and latex are used for many purposes. Aloe latex is the sticky residue left over after the liquid from cut aloe leaves has evaporated.

Aloe has been historically used for many of the same conditions for which it is used today -particularly constipation and minor cuts and burns. In India, it has been used by herbalists to treat intestinal infections, suppressed menses, and colic.

The constituents of aloe latex responsible for its laxative effects are known as anthraquinone glycosides. These molecules are split by the normal bacteria in the large intestines to form other molecules (aglycones), which exert the laxative action. Since aloe is such a powerful laxative, other plant laxatives such as senna or cascara are often recommended first.

Topically, it is not yet clear which constituents are responsible for the wound healing properties of aloe. Test tube studies suggest polysaccharides, such as acemannon, help promote skin healing by anti-inflammatory, antimicrobial, and immune-stimulating actions. Aloe?s effects on the skin may also be enhanced by its high concentration of amino acids, as well as vitamin E, vitamin C, zinc, and essential fatty acids.

Aloe has been used to treat minor burns. Stabilized aloe gel is applied to the affected area of skin three to five times per day. Older case studies reported that aloe gel applied topically could help heal radiation burns, and a small clinical trial found it more effective than a topical petroleum jelly in treating burns. However, a large, modern, placebo-controlled trial did not find aloe effective for treating minor burns.

Two small controlled human trials have found that aloe, either alone or in combination with the oral hypoglycemic drug, glibenclamide, effectively lowers blood sugar in people with type 2 (non-insulin-dependent) diabetes. An aloe extract in a cream has been shown effective in a double-blind, controlled trial in people with psoriasis.