With dermal preparations the therapeutic effect of the active ingredient is considerably influenced by factors such as the properties of the base and the type and conditions of the skin. In this respect, the correlation between the effect of the bases and the acuteness of the disease is the following: the more acute the disease, the more important the base and the less important the active ingredient. For dermal preparations there is consequently a therapeutic need for a differentiated spectrum of suitable bases. The choice of the appropriate vehicle plays a considerable role in the success of the treatment. The criteria for the selection of suitable vehicles are discussed on the basis of various examples.