Each Naprogesic tablet contains 275 mg of Naproxen sodium, which treats the cause of period pain symptoms by inhibiting the production of prostaglandins, tiny molecules that are the major culprits responsible for period pain. Naprogesic gives effective temporary relief from period pain symptoms for up to 8 hours.Naprogesic is gluten and lactose free and available in packs of 12 and 24 tablets.