Yes, probiotics are OTC. There are many kinds... Acidophilus is the most common (at almost all drug stores). If you want more of a variety I suggest going to a nutrition store (GNC, etc.). I take Acidophilus, Kyo-Dophilus and Phyto Pharmica Probiotic Pearls. The last 2 mentioned are pills that have a combination of several probiotics in them. I personally believe that a probiotic pill with a combination of more than 1 string is best. Also, which ever you choose, try picking one that needs to be refrigerated and has at least 1 billion cultures per dose.
IF you buy the Acidophilus, be aware that it might cause gas at first. Also, if you get the Acidophilus, don't start with more than 2 billion cultures per dose. I bought an Acidophilus pill with 5 billion per dose and I had gas cramps and D right away. Start with a smaller dose and work your way up (just like fiber!).
Last thing... Most probiotic "pearls" are enteric coated. This means the pill will not be digested in your stomach but will
open in your intestines. This is ideal. You want the good bacteria to hit your intestines where the bad resides. Lots of the "good bacteria" from regular pills don't quite make it to your intestines because they get digested in your stomach. If you're willing to pay the money look for enteric pills. OR, spend the money on the refrigerated kinds of probiotics.
Keep us posted.