Gargling to Prevent the Common Cold

Gargling is one of the best things to do to treat a sore throat.
Does it work to prevent the common cold?
In Japan, to prevent URIs, like the common cold, gargling has been strongly recommended (though like many virtually cost-free, simple and effective modalities, it’s not yet popular in the Western world).
In a randomized controlled study in 2005. “They found a significant drop in the incidence of the common cold, but not the flu, suggesting that simple plain water gargling is effective to prevent respiratory infections among healthy people. This virtually cost-free modality would appreciably benefit people both physically and economically around the world.”
Nearly 20,000 preschoolers were followed for 20 days in another study. Children in the exposure group were instructed to gargle at least once a day.
Whereas gargling with tap water reduced the chance of a fever by about a third, gargling with saline water or green tea lowered this risk even further by half (saline water) and two thirds (green tea) respectively.
The researchers concluded that “Gargling might be effective in preventing febrile diseases in children.”

Primary Sources:

K. Satomura, T. Kitamura, T. Kawamura, T. Shimbo, M. Watanabe, M. Kamei, Y. Takano, A. Tamakoshi. Prevention of upper respiratory tract infections by gargling: A randomized trial. Am J Prev Med 2005 29(4):302 – 307
M. Sakai, T. Shimbo, K. Omata, Y. Takahashi, K. Satomura, T. Kitamura, T. Kawamura, H. Baba, M. Yoshihara, H. Itoh. Cost-effectiveness of gargling for the prevention of upper respiratory tract infections. BMC Health Serv Res 2008 8(NA):258
T. Kitamura, K. Satomura, T. Kawamura, S. Yamada, K. Takashima, N. Suganuma, H. Namai, Y. Komura. Can we prevent influenza-like illnesses by gargling? Intern. Med. 2007 46(18):1623 – 1624
T. Noda, T. Ojima, S. Hayasaka, C. Murata, A. Hagihara. Gargling for oral hygiene and the development of fever in childhood: A population study in Japan. J Epidemiol 2012 22(1):45 – 49
K. Sato, T. Ohmori, K. Shiratori, K. Yamazaki, E. Yamada, H. Kimura, K. Takano. Povidone iodine-induced overt hypothyroidism in a patient with prolonged habitual gargling: Urinary excretion of iodine after gargling in normal subjects. Intern. Med. 2007 46(7):391 – 395
Fendrick AM, Monto AS, Nightengale B, Sarnes M. The economic burden of non-influenza-related viral respiratory tract infection in the United States. Arch Intern Med. 2003 Feb 24;163(4):487-94.