Echinacea for colds: what the evidence says and how to use it safely

Echinacea is a flowering herb. Cancer Research UK explains that it grows wild in the Great Plains and eastern parts of North America and is also grown in Europe. Common names include coneflower and purple coneflower, and there are several varieties, of which echinacea purpurea is the one most often sold as a herbal remedy.

Manufacturers make liquid extracts from the leaves, roots or the whole plant. It is sold as capsules, tablets, liquids to dilute, and ointment. Cancer Research UK says manufacturers promote it as a supplement that can prevent and lessen the symptoms of colds, flu and airway infections, although it also notes there is no standard dose and that some preparations do not say which variety they contain.

The NHS is direct about this. On its common cold page it says there is little evidence that supplements such as vitamin C, echinacea or garlic prevent colds or help you get better more quickly. The same page recommends rest, fluids and treatments for symptoms instead.

Cancer Research UK looks at echinacea from a cancer perspective, but its description of the research is helpful for everyone. It says laboratory and animal studies showed echinacea stimulated immune cells and reduced inflammation, but that there are no clinical trial results showing the same in humans; studies in people only showed changes to the immune system. It also reports a study in Cardiff in 2012 that seemed to show it is safe to take for up to 4 months, while some herbalists suggest limiting use to 8 weeks.

In short, laboratory activity has not been translated into proven benefit against colds in the UK sources used here. People who find echinacea helpful are describing their own experience, which can be real but is not the same as controlled evidence.

Cancer Research UK describes echinacea as generally safe, with severe side effects seeming rare. More common effects include headaches, dizziness, feeling sick, stomach ache, constipation and skin reactions such as redness, itching and swelling, which are more common in children. There is also a rare chance of a serious allergic reaction.

Longer use deserves caution. The charity says using echinacea for more than 8 weeks at a time might damage the liver or suppress the immune system, and herbalists recommend not taking it with medicines known to affect the liver. It adds that echinacea might interfere with how certain chemotherapy drugs, such as etoposide, work.

• Pregnant or breastfeeding: talk to a doctor before taking it, according to Cancer Research UK.

• Immune conditions such as autoimmune disease, HIV or AIDS: ask a doctor first.

• Taking immune-suppressing drugs: echinacea may work against them.

• Under 12: the MHRA is cited as warning of a risk of allergic reactions such as skin rashes.

• Taking any other medicine: the NHS advises checking with a pharmacist before taking a herbal medicine.

Quality varies. The NHS tells people to look for a traditional herbal registration (THR) mark and product code from the MHRA, which shows a herbal medicine has been licensed for use in England and meets safety standards. Cancer Research UK gives the same advice for European products and says THR products have been tested for quality and safety.

The NHS also advises not buying unlicensed herbal medicines online, saying they may not be safe, and it points out that herbal medicines are not recommended for children because not enough is known about their safety.

The NHS says you can usually look after a cold at home. Its advice includes resting, drinking plenty of fluids and using paracetamol or ibuprofen for aches and fever. Pharmacists can suggest decongestants or sore throat remedies, and it notes some cough and cold medicines are not suitable for babies, children and pregnant women.

It advises seeing a GP if you have a high temperature for more than 3 days, your symptoms get worse, you feel short of breath or have chest pain, or you have a long-term condition or weakened immune system and are worried. These are the situations in which a cold may be something more serious.