The present application relates to the technical field of shower system, and provides a device for adding a fluid medium to a shower system and a shower system. The device includes a water pipe assembly, a fluid medium pipe assembly and a valve body assembly. The valve body assembly includes a one-way valve for preventing back flow of the liquid medium and a water jet pump. The one-way valve is provided between a fluid medium inlet and a fluid medium outlet. The water jet pump includes a three-way valve pipe. A water inlet pipe of the three-way valve pipe is in communication with a water inlet, a water return pipe of the three-way valve pipe is in communication with the fluid medium outlet, and a water mixing pipe of the three-way valve pile is in communication with a water outlet.