Merck Manual

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Echinacea

By

Laura Shane-McWhorter

, PharmD, University of Utah College of Pharmacy

Last full review/revision Jan 2022| Content last modified Sep 2022
CLICK HERE FOR THE PROFESSIONAL VERSION

What is echinacea?

What claims are made about echinacea?

People take echinacea mostly to help prevent or treat viral infections in the upper respiratory tract, such as the common cold. Some people apply echinacea as a cream or ointment to treat skin disorders and promote healing of wounds. Proponents claim that echinacea has antioxidant and anti-inflammatory effects, helping to prevent cancer and other diseases. Antioxidants Antioxidants The human body needs various vitamins and minerals in order to thrive. Many of these nutrients can be found in whole, non-processed foods such as fruits and vegetables. However, most modern... read more protect cells against damage by free radicals, which are highly chemically active by-products of normal cell activity.

Does echinacea work?

Studies of echinacea's role in preventing and/or treating the common cold are inconsistent. The largest factor contributing to inconsistency is the variability of plant preparations (including different plant parts and species) and the supplement's ingredients.

Some preliminary evidence shows that taking echinacea may help decrease some of the inflammatory molecules (cytokines) that are involved in COVID-19 infection and may help diminish occurrence of acute respiratory distress syndrome (ARDS) that occurs in some people. However, this has not been substantiated.

No rigorous scientific studies support claims that echinacea helps prevent cancer or improves immunity, blood sugar, anxiety, and inflammation, or promotes wound healing.

What are the possible side effects of echinacea?

No dangerous side effects have been identified, but some people experience dizziness, fatigue, headache, and digestive upset. People with allergies to certain plants (for example, ragweed, chrysanthemum, marigold, daisies) may have allergic reactions when they take echinacea.

What drug interactions occur with echinacea?

Echinacea taken for longer than 8 weeks may interact with drugs that can cause liver damage, thereby increasing the risk of liver damage. Echinacea may negate the beneficial effects of immunosuppressants, which are used, for example, to prevent rejection of organ transplants. Echinacea may increase blood levels of caffeine by as much as 30%.

Recommendations

Echinacea is probably safe for short-term use, but whether it helps boost the immune system and prevents viral infections, such as the common cold, is unknown. People who have autoimmune diseases (such as rheumatoid arthritis and multiple sclerosis), have received organ transplants, or have an impaired immune system (for example, by AIDS or tuberculosis) should consult their doctor before they take echinacea.

NOTE: This is the Consumer Version. DOCTORS: CLICK HERE FOR THE PROFESSIONAL VERSION
CLICK HERE FOR THE PROFESSIONAL VERSION
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