Example inventions reduce pain of a user associated with primary dysmenorrhea (PD). Example inventions affix one or more patches externally on a dermis of the user, the patch including a flexible substrate, an adhesive on a first side adapted to adhere to the dermis of the user, a processor directly coupled to the substrate, and electrodes directly coupled to the substrate. Example inventions activate the patches, the activating including generating an electrical stimuli via the electrodes to activate one or more nerves of the user.
