Plant tars

Plant tars, also known as wood tars, are obtained by dry distillation of bark, wood, whole trunks and/or branches. In the past, they played an important role in dermatology. Their current use in external therapy is rather insignificant due to their potential side effects (see alsoPix betulina, Pix juniperi and others), as better, less toxic and safely effective preparations are available for the various indications.

Commission E did not deal with plant tars.

Plant/wood tars contain more than 1000 different chemical compounds, including polycyclic aromatic hydrocarbons (PAHs), phenols, cresols and naphthalene compounds, which are potential carcinogens.

The following plant tars are/were used in external therapy:

• beech tar
• Birch tar
• Coniferous wood tars (tars from pine species: Pix pinaceae)
• Juniper tar

Plant tars soothe itching and have anti-inflammatory, antimicrobial and anti-eczematous effects. In addition, plant tars inhibit proliferation and sebaceous gland activity and have anti-acanthotic and anti-infiltrative effects.

Plant tars are used to treat subacute and chronic eczema and psoriasis. Their therapeutic importance has diminished over the last two decades.

Apply 5-10 to 20 % preparations in different carrier media 1 -2 times daily in a thin layer.

Tar smells bad. There is a danger of soiling clothes or laundry. Furthermore, phototoxic reactions, contact allergies and folliculitis can occur. Resorption of polyaromatics is to be expected with the risk of nephrotoxic and carcinogenic effects when applied over large areas.

In the presence of exudative or pustular forms of psoriasis, in xeroderma pigmentosum, in dysplastic nevi syndrome, in Gorlin-Goltz syndrome, or in the case of an existing pregnancy or while breastfeeding, local therapy with plant tars is contraindicated. In the genital, scrotal, inguinal, perineal and axillary areas as well as in the area of the exposed skin (pototoxic effect) and in small children, application is only possible to a limited extent. The application area and time should also be limited.

Plant tars react phototoxically.

An application should only be made for a precise indication and then for a limited period of time, as plant tars probably contain mutagenic ingredients in low concentrations.

1. Sheaf C (2005) Topical therapy. In: Braun-Falco et al. dermatology and venereology. Springer publishing house Heidelberg, S. 1455
2. Schilcher H (2016) In: Guide to Phytotherapy, Urban & Fischer Verlag Munich, p. 250 ff.