Clinician Fact Sheet: Review of Herbal Supplements
January 1, 2000
Clinician Fact Sheet: Review of Herbal Supplements
Ginkgo (Ginkgo biloba L. Family: Ginkgoaceae)
1998 Retail Sales: $150,859,3281 Part Used: Leaf extract
Intended Indications
Allergic rhinitis, Alzheimer's disease, antioxidant, anxiety/stress, asthma, dementia, increases mental alertness, peripheral vascular disease, Raynaud's disease, senility, tinnitus, vertigo
Formulation and Dosage
• For memory or circulation: 120 mg/d in 2-3 divided doses
• For Alzheimer's, depression, or tinnitus: up to 240 mg/d in 2-3 divided doses
• Standardized leaf extract containing 24% flavone glycosides and 6% terpene lactones
Adverse Effects
Occasional GI upset, headache, dizziness, palpitations
Interactions
• Ginkgo may inhibit platelet aggregation so bleeding and prothrombin times should be closely monitored in patients on antiplatelet drugs and warfarin
• A theoretical interaction exists with other antiplatelet herbs; therefore, added vigilance is recommended if used in conjunction with ginger, garlic, or feverfew
• Patients taking antidepressants should be carefully monitored given ginkgo's reversible monoamine oxidase inhibitory capacity
• Ginkgo may reverse SSRI-induced sexual dysfunction
• Ginkgo can increase blood pressure when used concomitantly with thiazide diuretics
Contraindications
• Discontinue ginkgo use 7-10 days prior to surgery
• Safety not determined in pregnancy and lactation
St. John's wort
(Hypericum perforatum L. Family: Hypericaceae)1998 Retail Sales: $140,358,5601 Part Used: Leaves, flowering tops
Intended Indications
Antibacterial, antifungal, anxiety, mild-to-moderate depression
Formulation and Dosage
• 300 mg tid standardized to 0.3% hypericin extract (extracts standardized to hyperforin may soon appear on shelves as well)
Adverse Effects
Possibly increases photosensitivity in patients with fair complexions, occasional GI upset, dry mouth, dizziness, confusion
Interactions
• Concomitant use of MAO inhibitors, SSR inhibitors, and other antidepressant drugs should be avoided as well as photosensitizing agents
• One recent pharmacologic study showed that 14-day administration of St. John's wort decreased the bioavailability of digoxin by 25-30%2
Contraindications
• None documented
• Safety not determined in pregnancy and lactation
Recent Research
A recent study examined the reasons patients self-medicate with St. John's wort instead of seeking traditional health care.3 Extensive interviews were conducted with 22 women using St. John's wort. Upon review of the transcripts, several decision-making themes became evident. Study participants had a history of alternative medicine use and a desire for personal control of their health care. All St. John's wort users reported depressed mood and occasional irritability, cognitive difficulty, social isolation, and hormonal mood changes. Subjects reported self-diagnosis of minor depression, perceived high risk of prescription drugs, and a belief in the safety of herbal remedies. Additionally, participants noted barriers to and lack of knowledge of conventional health care providers and awareness of the ease of use and popularity of St. John's wort. Six of 22 (27%) participants had informed their primary care providers of their St. John's wort use. Users reported moderate effectiveness and few side effects.
Ginseng (Panax ginseng Family: Araliaceae)
1998 Retail Sales: $95,871,5441
Part Used: Roots
Intended Indications
Adaptogen, antioxidant, enhances immune function, fatigue, hypocholesterolemia, impotence, infertility, stress
Formulation and Dosage
• 100-200 mg/d standardized extract of 4-7% ginsenosides
• Continuous use not to exceed three months
• Preparations vary widely
Adverse Effects
Breast tenderness in women, nervousness and excitation that decreases with continued use of decreased dose, generally low toxicity from moderate doses of high-quality standardized product, postmenopausal bleeding
Interactions
• Since ginseng has been shown to decrease platelet adhesiveness in animal models, bleeding and prothrombin times should be monitored in patients taking anticoagulant and antiplatelet aggregating medications
• Variable effects on international normalizing ratio
• May interfere with digoxin activity or monitoring
• Because ginseng exhibits a hypoglycemic effect, blood glucose levels of diabetics should be monitored carefully
• Not indicated with caffeine or other stimulants
• Caution recommended for hypertensives
Contraindications
• None documented
• Safety not determined in pregnancy and lactation
Garlic (Allium sativum L. Family: Liliaceae)
1998 Retail Sales: $84,054,5201
Part Used: Bulb (clove), occasionally leaves
Intended Indications
Antibacterial, antimicrobial for mild respiratory and digestive tract infections, antiseptic, antispasmodic, atherosclerosis, lower blood pressure, lower serum cholesterol
Formulation and Dosage
• Total allicin potential of 3.6-5.4 mg/d or 10 mg/d alliin
• 4 g fresh garlic/d (multiple cloves)
Adverse Effects
Occasional GI upset, changes in gut flora, allergic skin reactions, odor may pervade breath and skin
Interactions
• Since garlic reduces platelet aggregation and increases fibrinolytic activity, bleeding and prothrombin times should be monitored in patients on antiplatelet drugs and warfarin
• A theoretical interaction exists with other antiplatelet herbs; therefore, added vigilance is recommended if used in conjunction with ginger, ginkgo, or feverfew
• May potentiate antihypertensives
Contraindications
• Discontinue garlic use 7-10 days prior to surgery
• Safety not determined in pregnancy and lactation
References
1. Blumenthal M. Herb market levels after five years of boom. HerbalGram 1999;47:64-65.
2. Johne A, et al. Pharmacokinetic interaction of digoxin with an herbal extract from St. John's wort (Hypericum perforatum). Clin Pharmacol Ther 1999;66:338-345.
3. Wagner PJ, et al. Taking the edge off: Why patients choose St. John's wort. J Fam Pract 1999; 48:615-619.
Additional Resources
Alternative Medicine Alert. Atlanta, GA: American Health Consultants; 1998;1:1-144; 1999;2:1-144.
McDermott JH. Herbal Chart for Health Care Professionals. American Pharmaceutical Association; 1999.
PDR for Herbal Medicines. Montvale, NJ: Medical Economics Co.; 1998.
The Review of Natural Products. St. Louis, MO: Facts and Comparisons.
Foster S, Tyler VE. Tyler's Honest Herbal. 4th ed. Binghamton, NY: The Haworth Herbal Press; 1999.