Herbal Drugs: Physiological effects

Last modified: Sunday, 31. May 2009 - 4:02 pm

Herbal drugs act on the body in a variety of ways. Echinacea may boost the body’s immune system and help fight off bacterial and viral infections. Garlic appears to lower levels of cholesterol in the blood. Gink-go may improve circulation by thinning the blood. The chemical compounds called flavonoids found in many herbal medications may help clear the body of harmful molecules called oxygen free radicals. However, exactly how echinacea, garlic, ginkgo, and other herbal drugs affect the body is still being studied.
Harmful side effects
All drugs, even conventional drugs, may cause toxic side effects in some people, and herbal drugs are no
exception. Critics of herbal drugs believe that they carry a greater risk of harmful side effects than conventional drugs do because the lack of manufacturing standards and quality control for herbal drugs leads to uncertainty about their potency. The skeptics cite a long list of documented toxic side effects and even fatalities caused by herbals, and they point to a list of herbal drugs known to cause serious side effects.
Proponents of herbal drugs argue that these medications must be safe because they have been used by countless people for thousands of years. They cite preliminary studies that show that some herbal remedies work as well as conventional drugs and produce fewer side effects. For example, an herbal mixture of fennel, peppermint, and wormwood improved symptoms of abdominal pain more effectively and with fewer side effects than the conventional drug metoclopramide, according to a study published in Phytomedicine. And many studies have shown that St. John’s wort seems to be as effective as standard antidepressants for mild to moderate depression while carrying a lower risk of side effects.
Following are some herbals known to cause serious side effects:
• Comfrey (Symphytum offtcionale). Ointments made from comfrey are used topically for wound and bone healing. Comfrey tea and pills have been prescribed by herbalists to treat gastrointestinal ulcers and diarrhea. However, the FDA advised dietary supplement manufacturers to take comfrey off the market in 2001 because of the gathering evidence that comfrey taken internally causes severe liver toxicity. The FDA also noted the lack of evidence for comfrey’s effectiveness. Comfrey should not be used by pregnant women or breastfeeding mothers.
Ephedra (Ephedra sinica), also called ma huang. This herb contains amphetamine-like substances called ephedrine alkaloids that can powerfully stimulate the heart and central nervous system. Ephedra is most often taken by young and middle-aged adults for weight loss, increased energy, and body building. The FDA has received and investigated hundreds of reports of serious side effects associated with ephedra, including high blood pressure, irregular heart rate, seizures, heart attacks, strokes, and death. People with high blood pressure, heart conditions, and neurologic disorders should not take ephedra. Pregnant woman should also avoid this herb.
• Kava. This herb has been promoted for a variety of uses, including relief of stress, anxiety, insomnia, and premenstrual syndrome. However, in 2001 the FDA wrote a letter to health care professionals advising them that kava had been implicated in 25 cases of severe liver toxicity in Germany and Switzerland. The FDA has also received several reports of serious injuries associated with kava in the United States, including one report of a previously healthy woman who required a liver transplant. Kava should not be used by pregnant women or breastfeeding mothers.
• Licorice {Glycyrrhiza glabra). Herbalists use licorice root and licorice juice to treat gastritis and stomach ulcers. However, licorice can cause significant sodium retention and high blood pressure in people who consume more than 3 grams per day for more than six weeks. Licorice should not be used by pregnant women or by patients with liver diseases such as chronic hepatitis or cirrhosis of the liver.
• Pennyroyal {Mentha pulegium). This widely available herb, drunk as an infusion, is used for digestive disorders, colds, and skin diseases. It is also used to induce abortions. However, pennyroyal is known to be toxic to the liver. One published report documented more than 20 cases of severe toxic reactions caused by this herb, including two fatalities. The PDR-HM recommends against using pennyroyal. Because pennyroyal can cause abortions at high doses, pregnant women especially should not use it.
• Finally, initial studies indicate that the following herbals are likely free of serious side effects: chamomile, garlic, ginkgo, peppermint, sabal {Sabal serrulata), saw palmetto, and St. John’s wort.
Long-term health effects
No one knows what the long-term health effects of taking herbal drugs might be. Long-term studies to assess the delayed effects or rare adverse effects of herbals have not been conducted.

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