Ammonium bituminosulfonate

Ichthammol or ammonium bituminosulfonate (brand name Ichthyol), also known as black ointment, is a medication derived from sulfur-rich oil shale (bituminous schists). It is used (sometimes in combination with zinc oxide) as a treatment for different skin diseases, including eczema and psoriasis (see below). It is applied on the skin as an ointments, most commonly containing 10% or 20% ichthammol.

Bituminosulfonates are considered topical therapeutic agents with very good tolerability.

The use of ichthammol in dermatology was promoted by German physician Paul Gerson Unna.

Ichthammol ointments, commonly known as black ointment or drawing salve, should not be confused with black salve, an escharotic (corrosive) paste intended to destroy skin tissue. In contrast, ichthammol does not have any corrosive properties on the skin.