Clindamycin
"I have been taking this for a horrible dental infection.  Dentist did a pulpectomy but was unable to do a full root canal because of the infection. 

I have been on the medication for two days now and have not experienced any of the side effects mentioned.  I do have stomach issues resulting from a recent gall bladder removal but nothing has changed since starting this medication.  I always take medications with plenty of water/liquid.  As others suggested, it is always a good idea to take antibiotics with a probiotic (pills/yogurt) and to continue it for a few weeks after the antibiotics."