The present invention relates to a transdermal therapeutic system for administering an active substance through the skin, said system being suitable for an application period of at least three days, comprising the layers arranged in the following order with respect to each other: a) a cover layer, b) an active substance layer comprising a polymer matrix containing the active substance, c) an adhesive layer comprising a contact adhesive, which consists of a mixture of one or more polyisobutylenes and one or more polybutenes, and d) a pull-off layer.