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Harmful Effects of Herbs

Recent surveys indicate that more than 50% of the population use some form of complementary and alternative medicine. In the United States, the sale of herbal medicines now exceeds $4 billion per year. Marketing campaigns often imply that any natural product is safe. However, herbal medicines are classified as dietary supplements and do not have to be proven safe before being released into the marketplace. Many herbs have been associated with adverse effects due to assay interference, herb-therapeutic drug interaction, or organ toxicity. The following list was compiled to provide a quick reference.

Common Name

Other Names

Intended Use

Adverse Effects

Aristolochic Acid

Snakeroot, birthroot, snakeweed, sangree root, serpentary, wild ginger

traditional Chinese herbs

nephrotoxicity, carcinogenic

Bitter Orange

Citrus aurantium, zhi xhi, zhi oiao, zhiqiao, kijitsu, neroli oil, Shangzhou,

weight loss, stimulant, athletic performance

tachycardia, vasoconstriction, hypertension, stroke

Borage oil

Borago officinalis, bee plant, bee bread, ox’s tongue, starflower oil

rheumatoid arthritis, hypertension

hepatotoxicity, lower seizure threshold, increase warfarin effect

Cat's Claw

Uncaria tomentosus, Una de gato, hawks claw

anti-viral, prevent colds & flu, chronic fatigue syndrome

hypotension, diarrhea, increase warfarin effect, inhibit CYP3A4

Chan Su

Chinese toad auricular glands

tonsillitis, sore throat, palpitations, heart tonic

vasoconstriction, hypertension, arrhythmia, digoxin immunoreactivity


Larrea tridentata, creosote bush, jarilla, greasewood, hediondilla

anti-neoplastic, anti-oxidant, arthritis remedy, cleansing tonic

cholestatic hepatotoxicity, nephrotoxicity, carcinogenic


Symphytum officinale, knitbone, nipbone, black root, bruisewort, consolidae radix

inflamed joints, wounds, gout, fractures, thrombophlebitis

hepatic veno-occlusive disease

Dan Shen

Salvia miltiorrhiza

angina pectoris, cardiovascular diseases

digoxin immunoreactivity, increase warfarin effect, platelet inhibition, fibrinolysis

Dong quai

Angelica senensis

menopause & menstruation

increase warfarin effect


Purple cone flower

colds, flu, URI, UTI, immune stimulant

allergic reactions, nausea, myalgia, hepatitis


Ma huang

weight loss, stimulant, athletic performance

arrhythmia, hypertension, stroke

Evening Primrose

Oenothera biennis, primrose oil

breast tenderness, PMS

lower seizure threshold


Tanacetum parthenium, Chrysanthemum

headaches, migraines, menstrual cramps, arthritis

increase warfarin effect


Allium sativum

lower blood pressure & cholesterol

increase warfarin effect, platelet inhibition


Teucrium chamaedrys

weight loss, general tonic

cholestatic hepatotoxicity


motion & morning sickness

increase warfarin effect

Ginkgo biloba

Maiden hair tree

forgetfulness, mental focus, tinnitus, claudication

increase warfarin effect, platelet inhibition, hypertension, seizures


Eleutherococcus senticosus (Siberian), Panax ginseng (Asian)

stress, endurance

decrease warfarin effect, digoxin immunoreactivity, hypoglycemia, Stevens Johnson, schizophrenia

Green tea

Camellia sinensis

cancer prevention, heart tonic, nausea & vomiting

decrease warfarin effect

Kava kava

Piper methysticum, kawa, ava, awa, gea ,gi, kao, kew, malohu, yagona, sakau

anxiety, insomnia

hepatoxicity, parkonsonism, GABA receptor blockade, calcium & sodium channel blockade


anti-inflammatory, thyroid tonic, metabolic tonic


Licorice root

anti-inflammatory, peptic ulcers

aldosteronism, hypokalemic myopathy, hypertension, increase warfarin effect


Lobelia inflata, Pokeweed, Indian tobacco, cardinal flower, asthma weed

anti-viral, anti-neoplastic


arrhythmia, respiratory failure

Lu Shen Wan

heart tonic

falsely elevated digoxin levels


digestive aid, sedative, heart tonic



Daturia inoxia


seizures, hallucinations, coma


Nerium oleander, dogbane, Thevetia peruviana, rose laurel

cancer, HIV, hepatitis, psoriasis, rheumatoid arthritis

arrhythmia, contact dermatitis, digoxin immunoreactivity, N&V, diarrhea, salivation, altered mentation

Passion flower

Passiflora incarnata

insomnia, anxiety

arrhythmia, drowsiness


Mentha puleguim, Hedeoma pulegoides, squawmint, mosquito plant, tickweed

induce menstruation, abortifacient, gout, fleas

hepatoxicity, nephrotoxicity, seizures


Gynostemma pentaphyllum, Jiaogulan, miracle grass, Xianxio, Southern Ginseng

lower BP & cholesterol

increase warfarin effect, nausea, diarrhea

St. John's Wort

Hypericum perforatum, goat weed

mood disorders, depression

induces CYP3A4 & P-glycoprotein drug transporter, increased drug clearance, lower therapeutic drug levels

Saw Palmetto

Serenoa serrulata, Sabal serrulata, saw tooth palm

BPH, polycystic ovary syndrome, hirsutism

5-alpha reductase inhibition, testosterone metabolism inhibition


Scutellaria laterifolia, pimpernel, hoodwort, monkey flower, mad-dog weed, quaker bonnet

insomnia, irritability, nervousness, snakebites, rabies

hepatotoxic, giddiness, stupor, confusion, seizures

Valerian root

Valeriana officinalis, capon's tail

Insomnia, anxiety

neurotransmitter inhibition by enhancing GABA, tachycardia, hypotension, headache, delirium


Corynanthe yohimbe, Pausinystalia yohimbine, yohimbehe, johimbe

aphrodesiac, impotence

Tachycardia, hypertension, urinary retention

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