[Effect of various kinds of tar and tar concentrations on anthralin erythema]

The effect of tar on anthralin-induced erythema was epicutaneously tested in ten patients. 3%, 5%, or 10% crude coal tar or coal tar solution was added to vaseline containing anthralin. A 5% or 10% tar preparation significantly suppressed the anthralin erythema induced by 0.5 to 1.0% anthralin having been applied for 24 hrs. In these concentrations, coal tar solution was at least as effective as coal tar itself.