A Guide to Common Medicinal Herbs

Here are some common medicinal herbs. Most herbs have not been completely tested to see how well they work or to see if they interact with other herbs, supplements, medicines, or foods. Products added to herbal preparations may also cause interactions. Be aware that "natural" does not mean "safe." It's important to tell your healthcare providers about any herb or dietary supplement you are using.

Chamomile

(Flower)

Considered by some to be a cure-all, chamomile is commonly used in the U.S. for anxiety and relaxation. It is used in Europe for wound healing and to reduce inflammation or swelling. Few studies have looked at how well it works for any condition. Chamomile is used as a tea or applied as a compress. It is considered safe by the FDA. It may increase drowsiness caused by medicines or other herbs or supplements. Chamomile may interfere with the way the body uses some medicines, causing too high a level of the medicine in some people.

Chamomile for the skin (topical) may be used to treat skin irritation from radiation cancer treatments. Chamomile in capsule form may be used to control vomiting during chemotherapy.

Echinacea

(Leaf, stalk, root)

Echinacea is commonly used to treat or prevent colds, flu, and infections, and for wound healing. Many studies have looked at how well echinacea works to prevent or shorten the course of a cold, but none were conclusive. Some studies do show some benefit of using echinacea for upper respiratory infections.

Short-term use is advised because other studies have also shown that long-term use can affect the body's immune system. Always check with your healthcare provider about any interactions with medicines that you are already taking. People allergic to plants in the daisy family may be more likely to have an allergic reaction to echinacea. The daisy family includes ragweed, chrysanthemums, marigolds, and daisies.

Feverfew

(Leaf)

Feverfew was traditionally used to treat fevers. It is now commonly used to prevent migraines and treat arthritis. Some research has shown that certain feverfew preparations can prevent migraines. Side effects include mouth ulcers if the leaves are chewed and digestive irritation. People who suddenly stop taking feverfew for migraines may have their headaches return. Feverfew should not be used with nonsteroidal anti-inflammatory medicines because these medicines may change how well feverfew works. It should not be used with warfarin or other anticoagulant medicines.

Garlic

(Cloves, root)

Garlic has been used all over the world in cooking and for its many medicinal properties. The compounds isolated from garlic have been shown to have antimicrobial, cardioprotective, anticancer and anti-inflammatory properties. These properties may play a role in the belief that garlic helps lower cholesterol and blood pressure. Unfortunately, the evidence is conflicting. The FDA considers garlic safe. But it can increase the risk of bleeding and should not be used with warfarin, a blood thinner. For the same reason, large amounts should not be taken before dental procedures or surgery.

Ginger

(Root)

Ginger is most commonly known as an herb for easing nausea and motion sickness. Research suggests that ginger may relieve the nausea caused by pregnancy and chemotherapy. Other areas under investigation in the use of ginger are in surgery and as an anticancer agent. It's wide range of actions may be due in part to its strong anti-inflammatory and antioxidative effects.

Reported side effects may include bloating, gas, heartburn, and nausea in certain people.

Gingko

(Leaf)

Ginkgo leaf extract has been used to treat a variety of conditions such as asthma, bronchitis, fatigue, and tinnitus. It is also used to improve memory and to prevent dementia and other brain disorders. Some studies have supported its slight effectiveness. But exactly how gingko works isn't understood. Only extract from leaves should be used. Seeds contain ginkgo toxin. This toxin can cause seizures and, in large amounts, death. Because some information suggests that ginkgo can increase the risk of bleeding, it should not be used with nonsteroidal anti-inflammatory medicines, anticoagulants, anticonvulsant medicines, or tricyclic antidepressants.

Ginseng

(Root)

Ginseng is used as a tonic and aphrodisiac, even as a cure-all. Research is uncertain how well it works, partly because of the difficulty in defining "vitality" and "quality of life." There is a large variation in the quality of ginseng sold. Side effects are high blood pressure and tachycardia. It's considered safe by the FDA. But it shouldn't be used with warfarin, heparin, nonsteroidal anti-inflammatory medicines, estrogens, corticosteroids, or digoxin. People with diabetes should not use ginseng.

Goldenseal

(Root, rhizome)

Goldenseal is used to treat diarrhea and eye and skin irritations. It is also used as an antiseptic. It is also an unproven treatment for colds. Goldenseal contains berberine, a plant alkaloid with a long history of medicinal use in both Ayurvedic and Chinese medicine. Studies have shown that goldenseal is effective for diarrhea. But it's not recommended because it can be poisonous in high doses. It can cause skin, mouth, throat, and gastric irritation.

Milk thistle

(Fruit)

Milk thistle is used to treat liver conditions and high cholesterol, and to reduce the growth of cancer cells. Milk thistle is a plant that originated in the Mediterranean region. It has been used for many different illnesses over the last several thousand years, especially liver problems. Study results are uncertain about the actual benefits of milk thistle for liver disease.

Saint John's wort

(Flower, leaf)

Saint John's wort is used as an antidepressant. Studies have shown that it has a small effect on mild to moderate depression over a period of about 12 weeks. But it is not clear if it is effective for severe depression. A side effect is sensitivity to light, but this is only noted in people taking large doses of the herb. St. John's has been shown to cause dangerous and possibly deadly interactions with commonly used medicines. It is very important to always talk with your healthcare provider before using this herb.

Saw palmetto

(Fruit)

Saw palmetto is used to treat urine symptoms from benign prostatic hypertrophy (BPH). But recent studies have not found it to be effective for this condition. Side effects are digestive upset and headache, both mild.

Valerian

(Root)

Valerian is used to treat sleeplessness and to reduce anxiety. Research suggests that valerian may be a helpful sleep aid, but the evidence is not consistent to confirm it. In the U.S., valerian is used as a flavoring for root beer and other foods. As with any medicinal herb, always talk with your healthcare provider before taking it.