The National Center for Complementary and Alternative Medicine (NCCAM) reveals that around 5 to 10 percent of Americans come down with the flu each year. Complications related to flu have resulted in 200,000 hospitalizations in the U.S. Meanwhile, though colds do not cause serious complications, they are one of the leading reasons for doctor visits and school or work absences.
Find out what research findings have to say about the use of natural products to treat the flu and colds, as compiled by NCCAM.
The Flu
Vaccination is the best protection against getting the flu. Starting in 2010, the Federal Government's Centers for Disease Control and Prevention has recommended annual flu vaccination for all people aged 6 months and older.
There is currently no strong scientific evidence that any natural product is useful against the flu.
Colds
Zinc
Zinc taken orally (by mouth) may help to treat colds, but it can cause side effects and interact with medicines. Zinc is available in two forms-oral zinc (e.g., lozenges, tablets, syrup) and intranasal zinc (e.g., swabs and gels). A 2011 analysis of clinical trials found that oral zinc helps to reduce the length and severity of colds when taken within 24 hours after symptoms start. The analysis also concluded that zinc, taken at low doses for at least 5 months, reduced the number of colds in children. Intranasal zinc has been linked to a severe side effect (irreversible loss of the sense of smell) and should not be used.
A note about safety: Oral zinc can cause nausea and other gastrointestinal symptoms. Long-term use of zinc, especially in high doses, can cause problems such as copper deficiency. Zinc may interact with drugs, including antibiotics and penicillamine (a drug used to treat rheumatoid arthritis).
Vitamin C
Vitamin C does not prevent colds and only slightly reduces their length and severity. A 2010 review of scientific literature found that taking vitamin C regularly (at least 0.2 grams per day) did not reduce the likelihood of getting a cold but was linked to small improvements in cold symptoms. In studies in which people took vitamin C only after they got a cold, vitamin C did not improve their symptoms.
A note about safety: Vitamin C is generally considered safe; however, high doses can cause digestive disturbances such as diarrhea and nausea.
From NCCAM.NIH.gov