I have only ever used brewers yeast as it is easy to just sprinkle a spoon on their food each time I feed them. I have always been leery of using pills since it seems it would be easy to overdose them.
You should be able to find it in most health food stores plus both Walmart and Walgreens sell it under their store labels.
You should be able to find it in most health food stores plus both Walmart and Walgreens sell it under their store labels.