Black Alder

A genus of 125 species of deciduous and evergreen, often thorny trees and shrubs that occur mainly in northern temperate regions. Rhamnus frangula and R. cathartica are ideal for hedges in a wild or woodland garden. The former, which grows wild in damp, peaty ground, has good autumn color, and its flowers are especially attractive to bees. It was once grown to make charcoal for small-arms gunpowder. Rhamnus purshiana, which is native to coastal redwood and mixed evergreen forests, is particularly noticeable in winter, forming groups of upright, silver-gray stems. The bark of Rhamnus species contains anthraquinone glycosides, which have strong purgative effect and cause severe griping pains, nausea, and vomiting unless stored for at least a year after drying. Rhamnus cathartica has been used as a purgative since at least the 9th century and was included in the British Phamacopoeia in 1650. Its effect is so drastic that it is no longer prescirbed, although buckthorn syrup, made from the berries, is used in veterinary practice. Rhamnus frangula and R. purshiana have superseded R. cathartica in medicine, having a gentler effect; the latter is mild enough for treating children and the elderly. Rhamnus purshiana was first listed in the U.S. Pharmacopoeia in 1890. Indiscriminate stripping of bark, leading to the destruction or some 100,000 trees a year, was reported as early as 1909, and shortages led to the exploitation of the much smaller R. alnifolia (alder buckthorn), which is similar in chemistry. Anthraquinones are pigments, so plants that contain them are almost always used for dyeing — a purpose that usually predates their importance in medicine. Rhamnus infectoria (Avignon berry) was one an important source of yellow dye; R. davurica and R. utilis were sources of the pigment known as "Chinese green indigo", used in dyeing silk. Fruits of R. cathartica, known as "Rhine berries", also yield an artist's pigment.

Used for centuries in northern and central Europe as a cathartic laxative, the bark of the frangula shrub contains chemicals that attract water to the intestines and stimulate intestinal movement, resulting in the emptying of the bowels. Before it can be used medically, frangula bark must be aged properly, which includes a one-year drying process. The fresh bark is not used because it contains chemicals, including emodin, that cause severe vomiting.

Deciduous, thornless shrub or small tree with ovate leaves, to 7cm (3in) long, turning yellow and brown in autumn. Tiny green flowers appear in axillary clusters in late spring, followed by red berries, 1cm (½in) across ripening to black.

Common Name:
Black Alder
Other Names:
Alder Buckthorn, Alder Dogwood, Black Dogwood, Frangula
Botanical Name:
Rhamnus frangula syn. Frangula alnus
Native Location:
Europe, N Africa, and Russia
Well-drained soil in sun or partial shade. Rhamnus cathartica prefers alkaline soil, R. frangula neutral to acid soil. Shorten of thin out branches, and remove dead wood, in late winter or early spring.
By seed sown when ripe; by greenwood cuttings in early summer; by layering in autumn or early spring.
Bark is stripped from young plants during spring and early summer, and it is dried for one to two years before being used in decoctions, liquid extracts, powders, and tablets. Bark from two-year-old plants is preferred in the case of R. frangula. Fruits (R. cathartica) are collected when ripe and they are made into syrup.
5m (15ft)
3-5m (10-15ft)
Parts Used:
Inner bark
A bitter, astringent, antiseptic herb that stimulates the liver and gall bladder, and acts as a purgative.
Medicinal Uses:
Internally for chronic, atonic constipation, abdominal bloating, hepatitis, cirrhosis, jaundice, and liver and gall bladder complaints. Externally for gum disease and scalp infections.
To treat hemorrhoids and poor digestion. Germany's Commission E has approved the use of frangula to treat constipation.
Typical Dose:
A typical dose of frangula for constipation may range from 1 to 2 cups of frangula tea per day, using the smallest amount of herb needed to relieve symptoms.
Possible Side Effects:
Frangula's side effects include loss of electolytes, particularly potassium, with long-term use.
Drug Interactions:
Digoxin, Diuretics, Loop Diuretics, Oral Corticosteriods, Thiazide Diuretics.
Taking frangula with these drugs may increase the risk of hypokalemia (low levels of potassium in the blood):
Acetazolamide, (Apo-Acetazolamide, Diamox Sequels)
Azosemide, (Diat)
Beclomethasone, (Beconase, Vanceril)
Betamethasone, (Celestone, Diprolene)
Budesonide, (Entocort, Rhinocort)
Budesonide and Formoterol, (Symbicort)
Bumetanide, (Bumex, Burinex)
Chlorothiazide, (Diuril)
Chlorthalidone, (Apo-Chlorthalidone, Thalitone)
Cortisone, (Cortone)
Deflazacort, (Calcort, Dezacor)
Dexamethasone, (Decadron, Dexasone)
Ethacrynic Acid, (Edecrin)
Etozolin, (Elkapin)
Flunisolide, (AeroBid, Nasarel)
Fluorometholone, (Eflone, Flarex)
Fluticasone, (Cutivate, Flonase)
Furosemide, (Apo-Furosemide, Lasix)
Hydrochlorothiazide, (Apo-Hydro, Microzide)
Hydrocortisone, (Anusol-HC, Locoid)
Hydroflumethiazide, (Diucardin, Saluron)
Indapamide, (Lozol, Nu-Indapamide)
Mannitol, (Osmitrol, Resectisol)
Mefruside, (Baycaron)
Methazolamide, (Apo-Methazolamide, Neptazane)
Methyclothiazide, (Aquatensen, Enduron)
Methylprednisolone, (Depo-Medrol, Medrol)
Metolazone, (Mykrox, Zaroxolyn)
Olmesartan and Hydrochlorothiazide, (Benicar HCT)
Polythiazide, (Renese)
Prednisolone, (Inflamase Forte, Pred Forte)
Prednisone, (Apo-Prednisone, Deltasone)
Torsemide, (Demadex)
Triamcinolone, (Aristocort, Trinasal)
Trichlormethiazide, (Metatensin, Naqua)
Urea, (Amino-Cerv, UltraMide)
Xipamide, (Diurexan, Lumitens)
Taking frangula with these drugs may increase fluid and electrolyte loss:
Cascara, (Cascara)
Docusate and Senna, (Peri-Colace, Senokot-S)
Taking frangula with this drug may be harmful:
Digitalis, (Digitek, Lanoxin)—May increase therapeutic and adverse effects of the drug.
All parts, especially the berries are harmful if eaten. Sap and berries are skin irritants.
Lab Test Alterations:
May confound results of diagnostic urine tests that rely on a color change by discoloring urine (pink, red, purple, or orange).
Disease Effects:
May worsen irritable bowel syndrome, Crohn's disease, and other intestinal ailments.
Supplement Interactions:
Increased risk of potassium depletion when used with Licorice, Horsetail Plant, or other stimulant laxative herbs, such as Black Root, Cascara Sagrada, Castor Oil, and Senna.
Encylopedia of Herbs by Deni Brown Copyright ©: 1995, 2001 Dorling Kindersley Limited pp 342-343
The Essential Herb-Drug-Vitamin Interaction Guide by Geo. T. Grossberg,MD and Barry Fox,PhD. Copyright©2007 Barry Fox,PhD. Pp.227-228