Echinacea Use Against Cold

Can you give me info on use of this to combat a cold? The person is 68 years old, and has smoked for years.

Echinacea stimulates the immune system by increasing the white blood cell count and stimulating macrophages that ingest foreign bacteria. It is effective in combating infections such as the common cold and influenza by protecting non-infected cells against viral infections. It has been found effective in allergy treatment because it helps prevent tissue inflammation due to harmful foreign toxins . It is also useful in infections of the mouth, throat and digestive system and for other complaints such as skin disorders and candida.
No side effects have been reported in clinical trials. There is no evidence that Echinacea loses its effect when taken for long periods.
For more information on echinacea, see Steven Foster's book "Echinacea, Nature's Immune Enhancer" or Christopher Hobb's "Echinacea: The Immune Herb!" (both available from Richters).