Yes they do! And here are some alternate uses for Alka Seltzer:
Clean a toilet: Drop in 2 tablets, wait 20 minutes, brush and flush.
Clean a vase: Fill with water and drop in 2 tablets.
Polish jewelry: Drop 2 tablets into a glass of water and immerse the jewelry for 2 minutes.
Clean a thermos bottle: Fill the bottle with water, drop in 4 tablets, and let soak for an hour.
Unclog a drain: Clear the sink drain by dropping 3 tablets down the drain followed by a cup of Heinz White Vinegar. Wait a few minutes, then run the hot water.
Wow...unclog a drain and get rid of indigestion!