Injection device having a thread having a variable pitch

An autoinjector for dispensing a liquid product, in particular a highly viscous medication, includes: a housing, a product container, which is arranged in the housing and has a slidable piston, wherein the piston can be slid in a dispensing direction in order to dispense the product contained in the product container, a forward drive element, which acts on the piston as the product is being dispensed, a first spring, which is preloaded such that the product can be dispensed from the product container by the sliding of the forward drive element and the piston, and a rotation element, which is operatively coupled to the forward drive element, wherein the first spring acts on the rotation element in such a way that the rotation element is set into rotation in order to dispense the product, wherein the rotation element or the forward drive element has a thread having a variable pitch.