Coal tar, pine tar and sulfonated shale oil preparations: comparative activity, efficacy and safety

Tar and sulfonated shale oil preparations are used in the treatment of a variety of inflammatory skin diseases, including psoriasis vulgaris; due to the high polycyclic aromatic hydrocarbon (PAH) content of tars, a possible relationship with cancer in humans has been postulated. On the other hand, the purity of sulfonated shale oils concerning PAHs guarantees a good tolerability during dermatologic therapy.

In this review, it is attempted to compare activity, efficacy and safety of coal tar, pine tar and sulfonated shale oil preparations which currently play a role in dermatologic treatment.

Primary sources of PAHs in the normal human environment are forest fires, cigarette smoke and combustion of fossil fuels for heating and energy. Thermal processing of fossil substances is also required for the production of tars and sulfonated shale oils. Due to individual manufacturing techniques, tars and sulfonated shale oils differ completely in their chemical composition. Still, sulfonated shale oils are often falsely grouped as tars because of their related origin and similar dermatologic indications. There is at least limited evidence of the activity and efficacy of various tars as well as sulfonated shale oil preparations in different frequent inflammatory skin diseases. This includes psoriasis vulgaris and atopic eczema of glabrous as well as hairy skin. There is still some concern about the long-term tolerability of tar preparations at least in some contexts. This, however, does not apply to sulfonated shale oil preparations. Consequently, at least their use should still be considered a rational drug treatment in dermatology.