A portable electronic device includes a battery, a transcutaneous electrical nerve stimulation (TENS) circuit, a power management circuit, a first output unit, and a second output unit. The TENS circuit provides a TENS electrical current. The power management circuit is coupled to the battery and the TENS circuit for managing a power distribution of the portable electronic device. The first output unit receives the TENS electrical current from the TENS circuit and outputs the TENS electrical current to a user. The second output unit receives a power signal from the battery and outputs the power signal to an external electronic device.