Thiamine(1+) is a primary alcohol that is 1,3-thiazol-3-ium substituted by (4-amino-2-methylpyrimidin-5-yl)methyl, methyl and 2-hydroxyethyl groups at positions 3, 4 and 5, respectively. It has a role as a human metabolite, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite and a mouse metabolite. It is a primary alcohol and a vitamin B1. It is a conjugate base of a thiamine(2+).