What is it?

Echinacea is a herbal remedy taken from the echinacea plant, the most popular variety of which is the purple coneflower plant called echinacea purpurea. It is one of the most widely used immune system stimulants in Europe. The American Indians were the first to recognise the value of the plant, using it for wound-healing and snakebites.

What does it treat?

It is a preventative treatment for colds, influenza and other respiratory tract infections. It is believed to work by stimulating a group of cells in the immune system known as the macrophages (part of the generic phagocytic cells). These cells destroy bacteria and viruses. It is believed to have other anti-fungal properties and is thus used as treatment for thrush and some skin problems. In tropical climates, it is also taken as a treatment for diarrhoea.

How is it taken?

Echinacea can be taken either as a tincture diluted with water or in the form of capsules, powder or pills. It is also available in cough lozenges and herbal drinks. The organic herbal remedy company, Bioforce, is one of the most popular brands available here. Its founder, the Swiss naturopath, Alfred Vogel, formulated the Echinaforce remedy from freshly harvested organic herbs grown in Switzerland. The dosage to be taken varies according to the potency of the echinacea product. In tincture form, the recommended dose is usually 15-20 drops three times daily for three to four weeks, followed by a month off before resuming again. Alternatively, 20 drops can be taken once a day for as long as desired. Echinacea products with higher potencies should be taken strictly as indicated on the packet.

Are there any contra-indications?

Although there has been a recent study which found echinacea to be safe during pregnancy, it is generally not recommended for pregnant women and young children. It also may interfere with immuno-suppressive therapies.

There is some evidence to suggest that echinacea is not suitable for sufferers from autoimmune diseases such as multiple sclerosis or disorders in which a heightened immune system response may be counterproductive (such as AIDS, asthma, leukaemia and tuberculosis). Some people have an allergic reaction to echinacea.

First-timer's experience (35year-old writer):

"I started taking it one day when I felt a cold coming on. That particular cold never arrived and now, three weeks later, I am still taking it and remain cold-free. It's too early to say really whether it will prevent me getting colds and flu this winter. The real proof will come when everyone else in the family gets a cold and I don't. "The downside of it is that it is a bit of a nuisance to take and you are never sure if you are taking the same dose each time. I mean, how big is a drop? Also, because it is recommended to take the tincture three times a day before meals, you can easily forget it sometimes. For this reason, I found it was a good idea to keep the bottle close to my everyday food items.

"On a psychological level, it feels good to be taking something that purports to boost my immune system."

An advocate's view (John Gormley, health spokesperson for the Green Party):

"I discovered echinacea a few years ago and have taken it intermittently ever since. There is no doubt that if you take if when you feel a cold coming on, you won't get the full-blown cold that lays you up. I honestly don't know how it works, but it does seem to boost the immune system. I think it is brilliant. Most people react to a cold by taking a lemon drink with paracetemol, which will stop your headache but won't make you feel better more quickly. "Instead, I take echinacea. I have been told, however, that you shouldn't take it all the time because after a while it can run down your immune system. Also, some people are allergic to it. So, I take it for a few days any time I feel something coming on or if I feel a bit flat. As a politician, you simply can't afford to be sick in bed; you don't have that luxury. "I remember when I lived in Germany years ago, echinacea was widely used. It is mainstream there, but there is still a more alternative vibe to it here."

Is there any scientific research to back it up?

Clinical trials in a placebo-controlled double-blind study in Sweden found that echinacea can improve the symptoms of colds and flu, shortening the course of the illness in 78 per cent of cases.

Dr Muiris Houston is on leave.