A treatment device may comprise a cover defining a cavity, wherein the cavity is configured to receive a part of a body. The cover may comprise at least one sheet having a composite structure. The composite structure may comprise at least two layers and at least one adhesive matrix situated between the two layers. At least one of the two layers may be permeable to a solvent, and the two layers may be permanently bonded to the adhesive matrix. The adhesive matrix may contain at least one active agent that is soluble in the solvent. When the active agent is dissolved in the solvent, the active agent may be released from at least one side of the cover.