Non-Steroidal Anti-Inflammatory Drug (NSAID) Response and Central Sensitization of Pain in Women With Dysmenorrhea

One dose of 550mg sodium naproxen taken at the onset of at least moderate pain after menstrual bleeding has started (i.e., at least 6/10 on the 0-10 numeric rating scale).

One dose of placebo capsule taken at the onset of at least moderate pain after menstrual bleeding has started (i.e., at least 6/10 on the 0-10 numeric rating scale).