Originally Posted by November
Fermcap or Five Star Defoamer work well too.
These drops work great. No more boilovers and they do not seem to have any effect on fermentation, krausen formation or head retention.
You can also use any drugstore anti-gas drops that contain Simethicone (eg. CVS Infant's gas relief drops). Just make sure they have no flavorings. About 3 drops is all I need to keep 7 gallons rolling in my kettle with no chance of a boilover.