Astragalus - Drug Interactions, Side Effects and Precautions of Use

Taxonomic Class

Fabaceae

Common Trade Names

Astragalus Power, Astragalus Supreme, Biomune OSF Plus, Nature's Way Astragalus Root, Neo-Cardio, Phytisone, Phyto Complete, Phytogen, Super Immuno-Tone, Thymucin

Common Forms

Available in capsules (100 mg, 150 mg, 200 mg, 250 mg, 400 mg, 470 mg, 500 mg), extract, tea, and tincture.

Source

The herb is derived from the root of the astragalus or Astragalus membranaceous plant, which is native to China, Korea, and Japan. The root may be fried with honey or chewed untreated; it has a sweet, licorice flavor.

Chemical components

Astragalus contains betaine, beta-sitosterol, choline, glycosides (astragalosides I through VII), plant acids (AMon-S, hexuroic acid), polysaccharides (astroglucans A through C), rumatakenin, sugar, saponins (more than 40 identified), and vitamin A.

Actions

Animal studies suggest effects that include stimulation of the immune system, possibly by the saponin and multiple polysaccharide constituents found in the astragalus root. Mice subjected to testing for stamina and stress resistance (swimming long distances and exposure to extreme temperatures) performed better when fed astragalus root.

Several test tube and rodent studies suggest that the herb successfully combats the scarring, inflammation, and other heart damage caused by the Coxsackie B virus.

Astragalus root saponins have been found to have diuretic activity.

These saponins have also been identified as having anti-inflammatory and antihypertensive activity.

Reported Uses

Astragalus is mainly used in traditional Chinese medicine to support and enhance the immune system. One study examined immune system stimulation for AIDS patients, and the preliminary results appeared favorable. A series of Chinese reports claim that a mixture of herbs including astragalus could induce seronegative conversion in a small number of HIV patients. Some people use the herb to speed healing because it may provide antibacterial activities or enhance one's own immune system. Others use astragalus as a protectant for the liver and kidneys.

Ten patients suffering from Coxsackie B viral myocarditis with depressed natural killer (NK) activity were given astragalus I.M. for 3 to 4 months. After treatment, the NK activity increased from 11.5% to 44.9%, whereas the control group NK activity remained unchanged . In another study, researchers observed an improved cellular immunity in blood samples of patients suffering from viral myocarditis.

According to various studies, astragalus may be beneficial for repair of the heart muscle. One study suggests that patients using astragalus experienced less anginal pain and improved electrocardiography readings compared with subjects using nifedipine. Another study demonstrated significant improvement of left ventricular function in postmyocardial infarction patients treated with astragalus compared with patients who did not receive the herb over a 4-week period. This study hypothesized that astragalus's antioxidant effects contributed to the benefits observed.

Dosage

Dried root: 1 to 4 g P.O. t.i.d.

Tincture: 1 dropperful P.O. b.i.d. or t.i.d.

Adverse Reactions

None reported.

Interactions

Antihypertensives: Interference with or increased hypotensive effects. Avoid using together.

Contraindications And Precautions

Use astragalus cautiously in patients taking immunosuppressants or those with autoimmune diseases.

Special Considerations

Find out why the patient has been taking astragalus.

Although no known chemical interactions have been reported in clinical studies, consideration must be given to the herbal product's pharmacologic properties and the potential for interference with the intended therapeutic effect of conventional drugs.

Caution the patient not to self-treat symptoms of cardiac or immune dysfunction before receiving appropriate medical evaluation because this may delay diagnosis of a potentially serious medical condition.

Advise the patient to consult a health care provider before using herbal preparations because a treatment that has been clinically researched and proved effective may be available.

Commentary

Astragalus has demonstrated some intriguing behaviors on the immune system. Although this herb is thought to have minor toxicities, research is in its infancy. Caution should be used when considering it for the treatment of serious insults to the immune system, such as AIDS, cancer, hepatitis, HIV infection, and myocarditis.