| Bearberry, also called uva-urse (Arctostaphylos uva-ursi) |
| High tannin content may reduce absorption of cationic minerals (eg, calcium) and some drugs. |
| Black walnut husk (Juglans nigra) |
| High tannin content may reduce absorption of cationic minerals (eg, calcium) and some drugs. |
| Cola nut (Cola acuminata) |
| Contains up to 2.5% methylxanthines, including caffeine and theobromine. May strengthen the effects of psychoanaleptic drugs and caffeinated beverages. |
| Dandelion (Taraxacum officinale) |
| Potassium-rich compounds have a diuretic effect that may enhance activity of diuretic medicines. |
| Echinacea |
| May counteract immune-suppressant drugs. Taken over time, may suppress immunity. |
| Ephedra |
| May increase side effects of stimulants. Its activity as adrenergic receptors presents the potential for a wide range of drug interactions. |
| Flaxseed (Linum usitatissimum) (not oil) |
| High fiber content. When taken concurrently with drugs or foods, may bind lipids, nutrients, and some drugs, reducing absorption. Contains compounds near the fiber layer known as lignins that metabolize to the substances enterolactone and enterodiol, which in laboratory analyses have been shown to weakly bind estrogen receptor. Specific effects have not been characterized. They may serve as weak estrogen agonists or antagonists; therefore, flaxseed has a theoretical potential to modulate effects of tamoxifen, ralox-ifene, hormone replacement, and/or other estrogenic drugs, as well as endogenous estrogens. |
| Goldenseal (Hydrastis canadensis) |
| Taken over time, can interfere with B vitamin absorption, especially B1 (thiamine). |
| Hawthorn (Cratageus oxyacantha, Cratageus monogyna) |
| Contains flavinoids that may enhance action of cardiac glycosides and ease their side effects. |
| Kava kava (Piper methysticum) |
| Banned by the FDA. May cause drowsiness, dizziness, and intoxication. May enhance effects of sedatives or hypnotics. Not recommended for consumption with alcoholic beverages. May impair ability to drive a motor vehicle or operate machinery. |
| Licorice (Glycyrrhiza glabra) |
| May impair action of drugs that cause potassium loss. May enhance action of corticosteroids. May counteract effectiveness of drugs used to treat hypertension. Contains glycyrrhizic acid, which can affect the hormone aldosterone that helps regulate blood pressure. For patients with high blood pressure, edema, or electrolyte imbalance, use of licorice root or its products can lead to sodium retention, excessive potassium excretion, and water retention. Some licorice products have the glycyrrhizic acid removed and are sometimes sold as deglycyrrhizic licorice. |
| Oak bark (Quercus alba, Quercus rubrum) |
| High tannin content may reduce absorption of cationic minerals (eg, calcium) and some drugs. |
| PC-SPES and SPES |
| Combination of several products including Dyer's woad, (Isatis indigotica Fort), licorice root, ginseng, reishi mushrooms, skullcap, chrysanthemum, rubescens, and saw palmetto. Risk of deep vein thrombosis, nausea, and mild leg cramps have been reported in patients treated with PC-SPES. Exhibits estrogenic activity; use of PC-SPEC may confound the results of standard or experimental therapies and may produce clinically significant adverse effects. Gynecomastia occurs in several patients. Licorice is a component of the herbal combination. Glycyrrhizin, a constituent of licorice, metabolizes to the aglycone glycyrrhetinic acid. The acid has a keto group at position 11, a structural feature shared with the adrenocortical hormone cortisol. When taken in large amounts, ingestion of licorice may affect mineral and carbohydrate metabolism and may dangerously elevate blood pressure. PC-SPES and SPES capsules contain undeclared prescription drug ingredients that could cause serious health effects if not taken under medical supervision. Laboratory analysis of the products by the California Department of Health Services found PC-SPES contains warfarin and SPES contains alprazolam, which are available only by prescription. |
| Raspberry leaves (Rubus idaeus) |
| High tannin content may reduce absorption of cationic minerals (eg, calcium) and some drugs. |
| Red clover (Trifolium pratense) |
| Contains the isoflavone biochanin A, which is similar in structure to the isoflavone genistein in soy. Biochanin A in laboratory tests is found to bind estrogen receptors. Specific in vivo effects have not been characterized. Biochanin A may serve as estrogen agonist or antagonist, therefore a theoretical potential exists for red clover to modulate effects of tamoxifen, raloxifene, hormone replacement, and/or other estrogenic drugs as well as endogenous estrogens. |
| Saw palmetto (Serenoa repens, Sabal serrulata) |
| A lipophilic extract of the saw palmetto berries is taken to treat symptoms of BPH (benign prostatic hypertrophy), as the lipophilic (hexane or ethanol) extract of these berries has been shown to relieve urinary symptoms without reducing the hypertrophy associated with BPH. Prostate cancer patients taking saw palmetto might experience false (low) readings on the PSA test. Clinicians should be informed when patients are taking this herb. |
| Sheep sorrel (Rumex acetosella) |
| Contains high amounts of oxalic acid, which binds dietary minerals and inhibits absorption. May inhibit absorption of some medications. |
| St John's wort (Hypericum perforatum) |
| May enhance effects of narcotics and selective serotonin reuptake inhibitors (SSRIs). Increases side effects of photosensitizing drugs, alcohol, and melatonin. Laboratory reports have suggested but not confirmed that the mechanism of action for St John's wort may involve monoamine oxidase inhibition, SSRI reuptake inhibition, increased melatonin production, and other effects. Induces the drug metabolizing enzyme cytochrome P450 3A4. Has the potential to interact with many medications, including CPT-11 (Irinotecan). |
| Turmeric (Curcuma longa) |
| Exhibits antiplatelet activity. May enhance effects of anticoagulant medications such as warfarin and potentiate bleeding. |
| Valerian (Valeriana officinalis) |
| Enhances the effects of sedatives and hypnotic drugs. |
| Vitex (Vitex agnus-cactus) |
| May stimulate prolactin and increase the supply of mother's milk. Due to action that may affect sex hormones, vitex should not be taken concurrently with birth control pills or other hormone therapy. |
