Botanical name

Aloe vera (L.) Burm. f. (Syn. A. barbadensis Mill.)
Aloe ferox Mill.

Family

Asphodelaceae

Common name

Aloe vera - Aloe, Aloe vera, Curaçao aloe, Medicinal aloe, Barbados aloe
Aloe ferox - Cape aloe, Bitter aloe, Red aloe

Information about the plant

The genus Aloe includes nearly 450 species and is mainly distributed in the tropical and subtropical regions of Africa, especially in South Africa. It can also be found on the Arabian Peninsula, in Mediterranean countries, in America, and in Asia. They are stemless, short-stemmed or arboreal leaf succulents, meaning that they can store water in their leaves, making them very well-adapted to climates with little or fluctuating precipitation. The large lance-shaped leaves are, therefore, thick and fleshy. Typically, the leaves are arranged in a rosette, from the center of which a very decorative, almost arboreal inflorescence grows. On this inflorescence, numerous large red, yellow or orange flowers are arranged in clusters.

The genus name Aloe, derived from Latin and Greek, is translated as “famous for its bitterness”. The bitterness is attributed to the yellow “Aloe juice” that is released from the fleshy leaves when they are cut off at the base and stored at an inclined angle. Each leaf drains 5 to 10 g of this juice. When dried, this juice solidifies into a hard, deep brown, opaque mass known as “Aloe”, which is medically used.
To obtain this drug, two Aloe species are used, the Aloe vera (syn. Aloe barbadensis) and Cape Aloe (Aloe ferox). Aloe vera originally comes from Sudan and the Arabian Peninsula and is nowadays widespread in tropical and subtropical regions of all continents due to cultivation and subsequent overgrowth. The specific epithet “barbadensis” refers to its existence on the West Indian island of Barbados. Cape aloe is native to the South African Cape. The specific epithet “ferox” comes from Latin and means “strongly proven, wild” and refers to the hard thorns in the center of the leaves and the sharp teeth along the edges of the leaves.

The storage tissue of Aloe vera leaves is also used. It consists of thin-walled cells that hold water in the form of mucilage. This mucilaginous parenchyma, known as Aloe vera gel, is obtained by “filleting” the leaves. Firstly, the leaf is cut across at the base and the top, and then the gel is cut out like a filet. These filets are washed to remove any remaining bitter leaf juice and then processed into a naturally turbid juice. Commercialized products include concentrated juice in the form of dry concentrates or fresh filets cut into cubes. Aloe vera gel products are consumed internally as juice as well as incorporated into cosmetics for external use. According to popular belief, Aloe vera gel has the reputation of a panacea.

Medicinally used parts of plants (herbal drug)

The dried juice of the leaves (Aloe) is used. Aloe consists of liver-colored, partially shiny pieces with shell-shaped surfaces.

Constituents of the herbal drug

Aloe contains anthranoids (hydroxyanthracene derivatives, “anthraquinones”), mainly aloins A and B, in addition to 2-alkyl chromones.

Quality of the drug

The quality of the following drugs or drug preparations is specified in the European Pharmacopoeia (Ph. Eur.):

• Cape aloe (Aloe ferox)
• Curaçao-Aloe (Aloe vera)
• Adjusted (standardized) aloe dry extract (Aloes extractum siccum normatum)

Medical applications

Recognised medical use

The HMPC has accepted the internal use of Cape and Curaçao aloe for short-term treatment of occasionally occurring constipation as “medically approved” (“well-established use”).

ESCOP: Cape and Curaçao aloe: for short-term use in cases of occasional constipation.

Traditional use

Not applicable

Herbal drug preparations in finished dosage forms

• Aloe dry extract standardized to anthranoids (aloin) in coated tablets
• Powdered Aloe (standardized) in solid medicines

Dosage

To ensure efficacy and avoid overdosing, Aloe should only be administered in the form of finished medicine standardized to anthranoids (aloin); the dosage can be found in the package leaflet. It is consumed in the evening before bedtime.

Preparation of a tea

Not applicable

Notes

Aloe should not be taken for longer than 1 to 2 weeks (intestinal mucosa-irritating laxative), continuous use increases intestinal inertia. Aloe should not be taken in cases of intestinal obstructions, appendicitis, inflammatory bowel diseases (e.g. Crohn’s disease, ulcerative colitis), abdominal pain of unknown origin and severe dehydration symptoms. A slight discoloration of urine during Aloe intake may occur.

Side effects

Rarely cramp-like gastrointestinal complaints occur (reduce the dose). Prolonged use of Aloe (laxative abuse) may cause problems with water and electrolyte balance, especially potassium losses. Additionally, protein and blood may appear in urine (albuminuria, hematuria). Chronic use leads to (reversible) pigment deposits in the intestinal mucosa.

Interactions

Chronic use of Aloe (laxative abuse) may lead to potassium deficiency, which may increase the effect of digitalis preparations (preparations containing cardiac glycosides). It could also affect the effectviness of antiarrhythmic drugs. Simultaneous intake with thiazide diuretics, adrenal steroids and licorice root can further increase potassium loss.

References

Herbal drug monographs

HMPC (2017,2022), ESCOP (2014), WHO vol. 1

Further literature

Commentary on the European Pharmacopoeia (Curaçao-Aloe, Nr. 257; Kap-Aloe, Nr. 0258; Aloe-Trockenextrakt, Nr. 0259)