Other research has estimated that about 53% of Americans regularly used at least one herbal product, with a high prevalence of use among the elderly. Research has revealed that many people do not reveal their herbal use to their physicians and pharmacists, increasing the chance of potentially serious herb-drug interactions.

When taking herbal preparations, it’s important to be aware of safety issues. The composition of herbal products sold in the U.S. is quite variable, and herbal remedies can produce side effects and interact with prescription medications. When purchasing a prescription drug, you generally know exactly what it contains because the medication has been carefully measured. By contrast, herbs are living organisms that can differ dramatically from plant to plant.

Because our metabolism is well suited for digesting plants and herbal medicines have a gentle, cumulative effect, they have little or no side effects for most people. However, like all medicines, a doctor should be consulted and dosage instructions should be adhered to, particularly for children, women who are pregnant or breast-feeding, and those regularly taking other prescribed medicines. Since herbs contain active ingredients, some of these compounds may interact negatively with medications.

Many people believe that herbs are just as effective as drugs, but without the side effects. Herbs do perform many healing functions in the body, but they must be used appropriately, not indiscriminately. Although herbal remedies are less likely than most conventional medicines to cause side effects, herbs nevertheless can be very potent. Moreover, not all plant life is beneficial. There are poisonous plants, and some of them are deadly, especially if used for long periods of time. Even certain herbs that are used only for healing purposes cannot be taken for extended periods of time.

Some herbs are associated with allergic reactions, dangerous interactions with conventional prescription medications, and serious psychiatric risks. There are multiple published reports of severe reactions to various herbs. The following are a few examples of the problems that can occur with the use of herbal medicine.

• Chamomile is one of most popular herbal teas and is known for its sedative, laxative, and spasmolytic effects. But because chamomile is a member of the ragweed family, it should be avoided by those who are allergic or sensitive to ragweed. First-time use of chamomile in some individuals can cause anaphylaxis as well as contact dermatitis and urticaria, an allergic skin reaction.

• Garlic, used in both herbal medicine and as a flavoring in some of our favorite recipes, has antithrombotic properties, cholesterol-lowering effects, and can enhance the pharmacological effect of anticoagulants. However, it can significantly prolong bleeding time, and should not be taken prior to surgery. Although garlic can improve the mechanisms of some medications, it can reduce the efficacy of others, such as anti-AIDS drugs.

• St. John's wort is one of the most widely used herbal supplements, and many doctors in Europe prescribe it over antidepressant medications. It is known as a potent reuptake inhibitor of serotonin, norepinephrine, and dopamine. Numerous studies have found St. John's wort to be as effective as antidepressant medications for treating depression. But because St. John's wort works in the same manner as antidepressant medications, it can induce an over-dose effect combined when with a serotonin reuptake inhibitor antidepressant. This condition, called "serotonergic syndrome," is a life-threatening drug reaction that causes the body to have too much serotonin.
  

"Even though herbal medicines are not devoid of risk, they could still be safer than synthetic drugs. Between 1968 and 1997, the World Health Organization's monitoring centre collected 8,985 reports of adverse events associated with herbal medicines from 55 countries. Although this number may seem impressively high, it amounts to only a tiny fraction of adverse events associated with conventional drugs held in the same database."

Part of the reason that herbs have the potential to create adverse reactions is because of their powerful medicinal attributes. Taken under the guidance of a qualified health care professional, herbal medicine has been shown to safe and effective. Problems tend to arise when people take herbal preparations outside of such guidance or neglect to tell health care providers about all the medication, herbal and dietary supplements they are taking.

References
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