Alka-Seltzer XS is a double action formula, with added caffeine, designed to act fast on pain. The soluble tablets contain aspirin and paracetamol, which together have pain relief, fever relief, and anti-inflammatory properties. Aspirin and paracetamol are rapidly absorbed and distributed around the body to provide fast relief of general pain such as headaches, migraines, period pain, toothache, and sore throat. Alka-Seltzer XS also provides symptomatic relief of fever, colds and flu, as well as rheumatic pain, sciatica, lumbago, fibrositis, and muscular aches and pains.