guaiacum resinA resinous extract from the heart wood (lignum vitae) of the Guiacum officinale tree of India. The resin was used in the 16th century as an alternative to mercury for the treatment of syphilis. Since then it has been used to treat rheumatic disorders but this use is abandoned. Today guaiac is used in a test for the presence of inapparent traces of blood (occult blood) in the stools.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005