The beneficial properies of thuja in the presence of warts and other skin growths(skin tags) may be due, to some extent, to some antiviral activity of its compounds, as shown by recent research. A group of German researchers reported in 2002 that an extract prepared from cedar leaf, alcohol, and water inhibits the reproduction of influenza virus type A, while a team of researchers in Japan found that an extract of Western red cedar was effective in treating eczema. Lastly, another group of Japanese researchers reported in 2003 that several compounds isolated from the stem bark of Japanese cedar appear to have some antitumor activity.