One in three Americans has taken herbal medicines in the past year to improve health. Annual purchases soar each year, costing billions in sales. Herbals that have been proven safe and effective deserve to be considered valid options for improving health. However, the effectiveness of many herbal medicines is still not proven, and it’s often difficult to tell fact from fiction in books and computer resources about herbs. Many are either for or against herbal medicines, making it difficult to get a true picture of the benefits and risks of using these products.
One important factor to keep in mind is that herbs act like medicines in the body and can cause strong unwanted effects. Table 1 lists some of the most common herbals used in the US, possible uses, side effects, and warnings or interactions with other medicines. As with prescription and over-the-counter medicines, dangerous side effects can occur when taking herbals, particularly if too much of the product is used. To cite one example, chamomile should not be taken if you have a history of asthma or allergic dermatitis, or if you take warfarin (Coumadin) or other blood thinners. The herbal should also be avoided if you are pregnant or breastfeeding, because it may trigger a miscarriage.1 Yet, most people would not think to look into the safety of drinking a cup of chamomile tea each night to help with sleep.
If you use herbal medicines, consult with your doctor before you start taking the herb, or let your physician and pharmacist know if you are already taking these products. Unfortunately, some studies have found that most people don’t tell their doctors they are taking herbal medicines.1 In some cases, they don’t consider herbals to be medicine; in other cases, they believe their doctors will criticize them for using the herbals. However, doctors need to know if you are taking these products so they can accurately judge whether particular symptoms are related to a medical illness or a side effect from an herbal medicine. Those who take herbal products should also keep a reliable, unbiased reference on hand. The National Library of Medicine and National Institutes of Health offer a comprehensive, free Internet resource that can be accessed at: www.nlm.nih.gov/medlineplus/herbalmedicine.html.
1) Fetrow CW, Avila JR. The complete guide to herbal medicines. 2000; Springhouse, PA:
Table 1. Common Herbal Medicines, Side Effects, Warnings, and Interactions
|Herb||Why People May Use This Herb||Examples of Side Effects||Examples of Warnings and Interactions|
|Echinacea||Treatment or prevention of colds, urinary bladder infections, burns Rash, dizziness, itching||Immune system can be overstimulated and then depressed with long-term use||Immune system can be overstimulated and then depressed with long-term use; long-term use can result in liver damage|
|St. John's wort||Internal use: depression, anxiety; Topical use: burns, skin lesions||Sun sensitivity, upset stomach, dry mouth, restlessness, trouble sleeping, constipation||May interact with birth control medicines, immunosup-pressants, cancer medicines, and other medicines for depression|
|Gingko biloba||Poor memory, poor leg circulation, dizziness, ringing in the ears||Upset stomach, headache, seizures, unusual bleeding or bruising||May interact with blood thinners like warfarin|
|Garlic||High blood pressure, high cholesterol, fatty deposits in arteries||Upset stomach, indigestion, nausea, allergic reactions, dizziness, sweating, underactive thyroid, stimulation of the uterus||May interact with blood thinners like warfarin|
|Saw palmetto||Benign prostate enlargement||Abdominal or back pain, diarrhea, nausea, painful urination, trouble emptying bladder||Use only if diagnosed with benign prostate enlargement and approved by your doctor|
|Ginseng||General health promotion and to increase energy levels, sexual function, athletic ability, fertility||Diarrhea, high blood pressure, insomnia, nervousness, chest pain, breast pain, rapid pulse, vaginal bleeding||May interact with drugs used to treat diabetes, blood thinners, depression medicines|
|Goldenseal||Internal use: upper respiratory infections; Topical use: inflammation, antiseptic to clean wounds, skin infections||Diarrhea, high blood pressure, mouth sores, nausea, numbness or tingling in arms or legs, seizures, dangerous heart rhythms||Taking large doses can cause death; may interact with heart and blood pressure medicines and blood thinners|
|Aloe||Topical use: wound healing, itching, burns; Internal use not recommended although oral capsules/extracts are available||Delayed wound healing, diarrhea, reddish urine, dehydration||Avoid taking aloe capsules if you have kidney or heart disease; may interact with digoxin, steroids, water pills|
|Siberian ginseng||General health promotion and to increase energy levels, sexual function, athletic ability, fertility||Diarrhea, high blood pressure, insomnia, nervousness, blurred vision, pimples, vaginal bleeding, low blood sugar in diabetic patients||Don't use when taking vitamins B1, B2, and C; don't use for more than 3 weeks; may interact with digoxin|
|Valerian||Insomnia, anxiety, muscle spasms||Fatigue, headaches, irregular heartbeats, excitability, nausea||May interact with sedatives; don't use if you have liver disease|
|Kava||Elevate mood, promote relaxation, treat anxiety, insomnia, menopausal symptoms||Visual disturbances, difficulty voiding, stomach discomfort, worsening of Parkinson disease, and serious muscle damage; heavy use may cause scaly skin rash||May cause liver injury, including hepatitis, cirrhosis, and liver failure; a maximum dose of 250 mg is suggested to prevent liver damage; avoid use if you have liver problems, are taking other medicines that can affect the liver, or have kidney disease, blood disorders, Parkinson disease, or depression|
|Black cohosh||Menopausal symptoms, painful menstruation, spasms of the uterus, high blood cholesterol, poor circulation in the legs||Overdose may cause nausea, vomiting, dizziness, visual disturbances, slow heart rate, sweating||Low incidence of bad side effects, but cases have been reported of liver injury, heart disorders, and convulsions|
|Evening primrose oil||Symptoms of arthritis, leg pain, breast pain, skin disorders such as eczema, acne, or psoriasis, weak bones, dry eye syndrome, nerve damage related to diabetes, prevent high blood pressure, start/shorten labor||Upset stomach, nausea, diarrhea, headache, possible seizures||Increased risk of bleeding when taken with warfarin or other medications that help prevent blood clots; avoid use if you have a history of seizures|
|Feverfew||Prevention of migraine headaches, arthritis pain, ringing in the ears, skin disorders, allergies, nausea and vomiting||Upset stomach, heartburn, bloating, nervousness, dizziness, insomnia, joint stiffness, fatigue, pounding heart, weight gain||Possibly unsafe when taken during pregnancy; may cause early contractions and miscarriage; may cause allergic reaction in people allergic to ragweed and other plants; interactions with numerous other drugs that are broken down by the liver|