Alka-Seltzer - Alka-Seltzer · On The Rocks. You haven't tried it yet? Oh boy. Alka-Seltzer On The Rocks works just like Alka-Seltzer Off The Rocks . . . only it's good enough to drink. Maybe even delicious? And even today, in 1966, nothing relieves an upset stomach and summer headache faster . . . or better than good old Alka-Seltzer. Try it at a picnic. Try it at the beach. Plop two Alka-Seltzers in water. Let it bubble away a few seconds. Add ice. A slice of lime. Cheers.