Andrographis

• Andrographis, also referred to as Indian echinacea, has a long history of use for treating colds.Evidence indicates it significantly reduces cold symptoms, says Dr. Evangeline Lausier of Duke University. A study published in the March 2010 issue of "Phytomedicine" conducted a double-blind placebo controlled trial on the effects of andrographis. Over 200 patients took either 200mg daily of andrographis or a placebo. During the first three days, both groups experienced a reduction in symptoms. From days three to five however, the andrographis group began to experience a significant improvement in symptoms, while the placebo group reported no change or a worsening of their condition. For best results, start supplementation within three days of the onset of symptoms.
  
  

Echinacea

• Perhaps one of the best known natural treatments for colds, echinacea has produced mixed results in clinical studies. Those showing positive results observed a 10 to 30 percent reduction in cold symptoms. According to WebMD, echinacea likely works to reduce colds despite mixed evidence. Integrative medicine expert David Leopold says that conflicting results likely stemmed from using different species of the herb and recommends echinacea purpurea. The University of Maryland Medical Center says a review of 14 studies found using this herb reduced the length of a cold by an average of 36 hours, and lists the suggested dosage as 300mg three times a day.
  
  

Vitamin C

• Long hailed for its beneficial effects on the immune system, vitamin C has gained a strong reputation as a natural treatment for a cold. WebMD reports mixed evidence on its benefits for treating colds, but notes some studies have found it might lessen the duration of a cold by 24 to 36 hours. The University of Maryland Medical Center notes that many studies only found symptom-reducing benefit in people who took vitamin C supplements regularly, not just when sick.
  
  

Zinc

• Zinc lozenges are also commonly used to treat colds. Along with other vital functions such as promoting normal growth and development , zinc plays a large part in promoting healthy immunity. This supplement has been long studied for its effects on the common cold and has always produced mixed results. According to a WebMD article last updated in December 2010, a recent review of 15 studies found it did reduce the duration of cold symptoms. It notes the different formulations used in different studies that might account for inconsistent results. The body most easily absorbs zinc picolinate, zinc citrate, zinc acetate, zinc glycerate and zinc monomethione.