Double actionpain relief caffeinefor rapid relief from headache with upset stomach alka seltzer xs contains two pain relieving agents to help relieve headacheit also contains an antacid to calm an upset stomach and buffering agents which empty the stomach to aid reliefalso suitable for relief of general pain such as migraine and period pains rheumatic and muscular pain and the symptomatic relief of colds and flualka seltzer is a registered trade