The invention relates to an injection device (100) for delivering liquid compositions, such as viscous hyaluronic acid gels. The device comprises a generally elongated housing (1) having first and second ends (20, 30) and the housing is adapted to receive an exchangeable cartridge (2) comprising the liquid composition proximal to the first end (20). A drive mechanism is arranged within the housing, comprising a motor and a power source, typically an electric motor and a rechargeable battery. The motor is coupled to a plunger rod which is intended to act on the cartridge (2) received in the housing (1) in order to expel the liquid composition contained in the cartridge (2). A first actuation means (8) for actuating the drive mechanism is provided on an upper side of the elongated housing (1), proximal to the first end (20) of the housing (1) and a second actuation means (9) for actuating the drive mechanism is provided at the second end (30) of the housing (1).
