The herbal remedy echinacea decreases the odds of catching a cold cold by more than half, a new study has found.

Scientists from the University of Connecticut School of Pharmacy in the US reviewed 14 previous studies. They found that the herbal product cut cold progress by 58%. It also reduced how long a cold lasted by 1·4 days.

In one of the 14 studies the researchers reviewed, echinacea was taken alongside vitamin C, and this combination cut the cold incidence by 86%.

Despite previous evidence supporting echinacea's benefit in reducing effects of the common cold, there has still been debate over its benefits.

Dr Craig Coleman, one of the study's authors, said: "With over 200 viruses capable of causing the common cold, echinacea could have modest effect against rhinovirus but marked effects against other viruses." Rhinovirus is the most common cold virus.

Native Americans were the first to use the echinacea flower for medical purposes, to heal wounds. 

The researchers said they did not yet know exactly how echinacea reduced the impact of colds.

Published in The Lancet Infectious Diseases journal, the study found that even when patients were directly inoculated with a cold-causing virus, echinacea reduced the cold incidence by 35%.

Adults catch an average of two to five colds a year, while schoolchildren get between seven and 10, British estimates say.