Taking 300 milligrams per day of Echinacea at the first sign of a cold appears to do little to reduce symptoms or speed recovery, according to a report released Monday.

Echinacea, derived from the purple coneflower, is sold over the counter as an immune-system strengthener and cold remedy. Despite its popularity, recent studies have suggested that the herb may do little to prevent or treat the common cold.

Adding to the evidence, the current study found that people who were given Echinacea within 24 hours of their first cold symptoms reported equally severe symptoms as people who received a placebo drug, and both groups took the same amount of time to recover.

“There is currently no conclusive evidence that the root or herb portions of Echinacea are useful in the treatment of the common cold,” study author Dr. Steven Yale of the Marshfield Clinic in Wisconsin told Reuters Health.

“I would not recommend the use of Echinacea for treatment of the common cold” until large studies clearly show it can shorten colds and ease symptoms, he added.

In 1997 alone, Americans spent around $27 billion out-of-pocket on alternative medicine. Some of that went to fighting and preventing common colds, which strike most adults between 2 and 4 times each year.

However, recent research has cast doubt on whether the herbal preparation can treat colds. A study published last year found that children who took Echinacea as soon as they developed a cold showed no difference in the severity or duration of cold symptoms than children who took a placebo pill. (http://nccam.nih.gov/health/alerts/echinacea/index.htm)

Another study published last month showed that Echinacea may also do little to prevent colds.

To further test the herbal medicine’s prowess at fighting colds, Yale and his co-author Dr Kejian Liu randomly assigned 128 people to take capsules three times per day containing either 100 milligrams of Echinacea purpurea or a placebo within 24 hours after developing a cold, and continue to do so until their colds resolved.

Most people got over their colds after seven days, the authors write in the Archives of Internal Medicine. Those who took Echinacea had just as severe symptoms and suffered just as long as people on a placebo.

Yale explained that some studies have still shown that Echinacea may help prevent and treat colds. These conflicting results are likely due to differences between studies in the amount, type and part of the Echinacea plant used, he explained.

Despite the contradictory evidence, many people still turn to Echinacea, probably because they think it will work for them and is relatively safe, Yale said.

“However, it is important to recognize that herbs are drugs and may have serious side effects - including drug interactions - when taken with some prescription medications,” he cautioned.

SOURCE: Archives of Internal Medicine, June 14, 2004.