The medicinal part is the bark. Salix nigra is American Willow.
Flower and Fruit
The male flowers are yellow and the female green. They are dioecious and appear at the same time as the leaves on leafy stems in erect catkins. The male catkins are densely blossomed and cylindrical, up to 6.5 cm by 1 cm and have 2 stamens. The female catkins are cylindrical, 4.5 cm by 7 mm. The seeds have a tuft of hair.
Leaves, Stem, and Root
Silver Willow is a 6- to 18-m high tree or bush with fissured gray bark. The leaves are short-petioled, lanceolate, acuminate, and become cuneate at the base. They are finely serrate, silky-haired, and tomentose underneath, and blue-green matte in color.
The annual twigs are not easy to break off at the base.
The plant is indigenous to central and southern Europe.
White Willow bark consists of the bark of the young, 2- to 3-year-old branches harvested during early spring of Salix alba, Salix purpurea, Salix fragilis, and other comparable Salix species.
Black Willow, Cartkins Willow, European Willow, Pussywillow, Salicin Willow, Withe Withy,Withy
Actions & Pharmacology
Glycosides and esters yielding salicylic acid (1.5-12%): salicin (0.1-2%), salicortin (0.01-11%) and salicin derivatives acylated to the glucose residue (up to 6%, including fragilin, populin)
The efficacy of the drug is due mainly to the proportion of salicin present. After splitting of the acyl residue, the salicin glycosides convert to salicin, the precursor of salicylic acid. Salicylic acid is antipyretic, antiphlogistic and analgesic. White Willow bark is the phytotherapeutic precursor to acetylsalicylic acid (aspirin).
The salicin component is responsible for the anti-inflammatory and antipyretic effects. The tannin content has astringent properties on mucous membranes.
Indications & Usage
Approved by Commission E:
Salicin is useful in diseases accompanied by fever, rheumatic ailments, headaches and pain caused by inflammation.
Folk medicine uses include toothache, gout, gastrointestinal disorders, diarrhea, and wound healing.
Willow Bark is contraindicated in patients that have a hypersensitivity to salicylates. Salicylates should not be used in children with flulike symptoms due to the association of salicylates with Reye's Syndrome.
Patients with an active gastric or duodenal ulcer, hemophilia, asthma, or diabetes should avoid Willow Bark preparations.
Salicylates should be avoided during pregnancy.
Salicylates have been associated with rashes in breastfed infants; use is not recommended.
Precautions & Adverse Reactions
No health hazards are known in conjunction with the proper administration of designated therapeutic dosages. Stomach complaints could occur as a side effect due to the tannin content.
There have been reports of metabolic acidosis in children with normal renal and hepatic function who were treated with salicylates and carbonic anhydrase inhibitors for joint pain and glaucoma. This combination should be avoided (Cowan, 1984).
Due to the salicin component of White Willow, caution should be exercised when used in combination with salicylates and other nonsteroidal anti-inflammatory drugs. There are reports that salicylate decreased serum naproxen concentrations markedly and increased serum naproxen clearance by as much as 56% (Furst, 1987).
Though there are no reports of interactions with drugs that affect blood-clotting times, and some studies suggest that thrombocyte inhibition is unlikely. Antiplatelet medications and any medication that prolongs the PT time should not be used with Willow Bark (Wichtl & Bisset, 1994).
Alcohol and barbiturates may mask the symptoms of salicylate overdosage and may enhance the toxicity of salicylates.
Mode of Administration
Liquid and solid preparations for internal use. Combinations with diaphoretic drugs could be considered. Drug extracts are contained in some standardized preparations of analgesics/antirheumatics, hypnotics/sedatives, and gastrointestinal remedies.
To prepare an infusion, use 2 to 3 g of finely cut or coarsely powdered drug in cold water, boil, allow to steep for 5 minutes, then strain.
6 to 12 g (average daily dose corresponding to 60-120 mg total salicin).
Infusion–1 cup 3 to 4 times daily. (1 teaspoonful = 1.5 g drug)
Liquid Extract–(1:1 in 25% alcohol) 1 to 3 mL 3 times daily.
Powder–1 to 2 g, several times a day.