This information describes the common uses of Echinacea, how it works, and its possible side effects.

Common Name

Coneflower; purple coneflower, Black Sampson; Sampson root, Sonnenhut, Igelkopfwurzel

How It Works

Echinacea does not appear to prevent the common cold, but it may shorten the duration of colds or be of benefit in the early treatment of influenza when taken within 24–48 hours of the first symptoms.

Echinacea extract appears to stimulate immune cells in laboratory and animal studies. Some compounds found in echinacea appear to reduce inflammation, relieve pain, and kill bacteria and viruses directly. Human studies have found that echinacea is not effective for preventing the common cold or to treat respiratory infections, but it may shorten the duration of colds. One large clinical trial suggested a specific echinacea formulation was as effective as  a prescription drug to treat influenza, with fewer side effects.

Few studies have been conducted on echinacea with respect to cancer or cancer treatment. Some studies suggest that echinacea could alter the effectiveness of some anticancer drugs or cause adverse effects.

Purported Uses

  • To treat the common cold
    Most studies do not support this use. One clinical trial supports the use of echinacea for reducing the length of colds, but not the severity of symptoms. One large trial suggests a specific echinacea formulation could be as effective as a prescription drug to treat influenza, with fewer side effects.
  • As an antiseptic
    Laboratory studies suggest that echinacea has antibacterial qualities.
  • To stimulate the immune system
    Laboratory and animal studies suggest that echinacea extracts stimulate different parts of the immune system. Human studies suggest immune-changing effects.
  • To treat viral infections
    Laboratory studies suggest that echinacea has antiviral properties and a human study suggests a specific echinacea formulation could be as effective as a prescription drug to treat the influenza virus.
  • For faster wound healing
    Animal models suggest wound-healing properties, but studies have not been conducted in humans.

Do Not Take If

  • You are taking immunosuppressants (eg, tacrolimus, cyclosporine): Echinacea may lessen their effect.
  • You are taking drugs that are substrates of cytochrome P450: Echinacea may increase the risk of side effects of these drugs.
  • You are taking tamoxifen: Lab studies suggest echinacea may weaken the effects of tamoxifen.
  • You are taking etoposide: Echinacea caused low blood platelets in a patient receiving etoposide.
  • You are taking P-glycoprotein (P-gp) substrate drugs: Lab studies suggest echinacea could alter effectiveness of some of these drugs.
  • You are taking oseltamivir: Lab studies showed that echinacea reduced the active formation of this drug, and may therefore reduce effectiveness.
  • You are undergoing eyelid surgery: Echinacea increases the risk of dry eye syndrome.
  • You have allergies or asthma: Allergic reactions have been reported with echinacea.
  • You are pregnant or nursing: Echinacea has not been adequately studied in pregnant women.

Side Effects

Common: Headache, dizziness, nausea, constipation, mild stomach pain, skin rash, irritation

Rare: Serious allergic reactions

Case Reports – Oral
Worsening of a chronic blistering skin disease:
In a 55-year-old man with a history of pemphigus vulgaris, which was controlled with immunosuppressants. Only partial remission was reported after he was treated again with immunosuppressants.

Reduced white blood cell count: In a 51-year-old woman following chronic use of echinacea. Her white blood cell count returned to normal levels 7 months after discontinuing echinacea supplements.

Severe hepatitis: In a 45-year-old man who complained of fatigue and jaundice lasting one week, linked to daily high doses of echinacea used to strengthen his immune system after catching the cold.

Increased eosinophil count in the bloodstream: In a 58-year-old man, there was an increase in this type of white blood cell following use of echinacea. His symptoms improved after discontinuing echinacea.

Low platelet and blood-coagulation disorders: Two case reports involve a 61-year-old cancer patient whose use of echinacea likely interacted with etoposide, and a 32-year-old man who used echinacea to alleviate respiratory symptoms.

Severe acute liver failure: In a 2-year-old girl, likely cause by echinacea toxicity.

Case Report – Topical
Eye irritation and conjunctivitis:
7 reports following use of topical echinacea were received by The National Registry of Drug-Induced Ocular Side Effects. Symptoms resolved after discontinuing echinacea.

Special Point

Echinacea supplements available in stores contain varying amounts and different species of echinacea. Therefore, the beneficial results seen with echinacea in clinical trials may not apply to a product that contains a different species or quality of this herb. One study found that about half of the echinacea brands tested did not contain the type or quality of echinacea that they claimed on the label.