Echinacea is an herb that has been used to treat or prevent symptoms related to illnesses such as common colds and the flu. To date, studies have revealed mixed results as to whether echinacea prevents or shortens illness.

The species of plants known as Echinacea are flowering perennials that are native to the East and Midwest regions of the United States. There are nine species, and three are used in supplements: Echinacea purpurea, Echinacea angustifolia and Echinacea pallida. Echinacea is sold under various trade names and is one of the most popular supplements in the United States.

The National Institutes of Health (NIH) has conducted two studies that have revealed no link between taking echinacea regularly (e.g., on a daily basis) and the prevention of colds and other infections. However, other studies have indicated that echinacea may provide benefits to those with upper respiratory infections. The NIH and other organizations are continuing to explore the potential link between echinacea use and a reduction in the severity and duration of illnesses such as colds and the flu.

In most people, echinacea does not cause side effects. However, some people may experience an allergic reaction, the most serious of which is anaphylactic shock, a life-threatening, whole-body allergic reaction associated with a collapse of the circulatory system. Other potential side effects include gastrointestinal symptoms, dizziness, nausea, swelling and rash.

People with certain allergies should not take echinacea. This is particularly true of people who are allergic to plants in the Asteraceae or Compositae family. Examples of such plants include ragweed, chrysanthemums, marigolds and daisies.

Few studies have been performed on the potential interactions between echinacea and medications, supplements or other herbs. In rare cases, echinacea has been linked with liver inflammation (hepatitis). As a result, patients taking certain medications are urged to avoid taking echinacea. It is important to tell physicians and other medical professionals about all supplements and herbs that a patient is taking.

Echinacea is an herb that has been used to prevent and treat symptoms related to respiratory illnesses such as common colds and the flu. For many years, people have believed that this herb stimulates the immune system to fight infections. To date, studies have revealed mixed results as to whether echinacea prevents or shortens illness.

The species of plants known as Echinacea are flowering perennials that are native to the East and Midwest regions of the United States. There are nine species, and three are used in supplements: Echinacea purpurea, Echinacea angustifolia and Echinacea pallida. The whole plant and its roots are used to make supplements, depending on the brand. A liquid extract made from the root of Echinacea purpurea is the most popular form of echinacea supplement. The roots and above-ground plant parts have different chemical properties that can influence the effectiveness of the herb.

Echinacea is sold under various trade names. It is one of the most popular supplements in the United States. The National Institutes of Health (NIH) estimates that echinacea supplements account for about 10 percent of all supplement sales in the United States. In addition to being used to prevent or treat infections such as a cold or the flu, people have used echinacea to treat wounds and skin problems, including acne and boils (tender, swollen areas that form around hair follicles).

Scientific studies into the health effects of echinacea have revealed mixed results. The NIH  conducted two studies that revealed no link between taking echinacea regularly (e.g., on a daily basis) and the prevention of colds and other infections. As a result, the NIH concluded that echinacea does not appear to be useful in preventing these illnesses.

However, other studies have indicated that echinacea may provide benefits to those with upper respiratory infections. The NIH and other organizations are continuing to conduct clinical trials to explore the potential link between echinacea use and a reduction in the severity and duration of illnesses such as colds and the flu.

One of the problems with herbal supplements is the issue of standardization. Supplements are not regulated by the U.S. Food and Drug Administration (FDA) and manufactureres are not obligated to comply with the safety standards required of medications. In addition, it is difficult to know what part of the plant is contained in the supplement, which could influence the effectiveness of the herb. It is also difficult to reliably determine what species of echinacea and how much echinacea are contained in supplements. Furthermore, even plants of the same species may have different variations of active compounds depending on factors such as individual genetic differences, how the plant was grown and how it was harvested.

The potential effect of echinacea on other medical conditions is also being studied. These conditions include:

• Genital herpes
• Radiation-associated toxicity
• Skin and oral wounds
• Vaginal yeast infections (candidiasis)

People with certain allergies should not take echinacea. This is particularly true for people who are allergic to plants in the Asteraceae or Compositae family. These are large families that contain a variety of plant types, including ragweed, chrysanthemums, marigolds and daisies.

People with asthma or atopy (a genetic tendency to experience allergic reactions) are also more likely to experience adverse reactions to echinacea.

In most people, echinacea does not cause side effects. However, some people may experience an allergic reaction that may include symptoms such as rashes and increased asthma symptoms. In its most severe state, anaphylactic shock may occur, which is a life-threatening, whole-body allergic reaction.

Gastrointestinal side effects have also been reported in people who use echinacea. Other side effects known to occur with use of this herb include:

• Dizziness
• Muscle aches
• Nausea
• Rash

Patients taking echinacea are urged to discuss this and any other supplement or herb use with their physicians. Few studies have been conducted on the potential interactions between herbs such as echinacea and medications, supplements or other herbs. In rare cases, echinacea has been linked with liver inflammation (hepatitis). As a result, patients taking certain medications are advised to avoid taking echinacea. These include the following:

• Acetaminophen (over-the-counter pain relief medication)
• Amiodarone (heart medication)
• Anabolic steroids (drugs that promote muscle growth)
• Methotrexate (cancer drug)
• Oral antifungal medications

Because echinacea is thought to stimulate the immune system, it is not likely to be a good choice for people who take drugs designed to suppress the immune system. Such drugs may include azathioprine, cyclosporine and corticosteroids (e.g., prednisone).

Some studies have indicated that echinacea may increase the rate at which the liver metabolizes many drugs, causing the medications to move through the body too quickly. This can make the drugs less effective.

Preparing questions in advance can help patients to have more meaningful discussions with their physician regarding their conditions and treatments. Patients may wish to ask their doctor the following questions related to echinacea:

1. What is your opinion on the effectiveness of echinacea in reducing cold or flu symptoms?
   
   
2. What type of echinacea, if any, do you recommend?
   
   
3. How will I know if echinacea is working?
   
   
4. How long should I take echinacea?
   
   
5. Will it be evident if I am taking too much echinacea?
   
   
6. What should I do if I start experiencing side effects related to echinacea?
   
   
7. Can I take cold and flu medications at the same time I take echinacea?
   
   
8. Are there certain medications that I should stop taking while I’m on echinacea?
   
   
9. Will certain herbs interact poorly with echinacea?
   
   
10. Are their alternative herbs or medications that might serve as a more effective treatment?