Metronidazole
"I am on flagyl 500mg 3X a day. I have a severe case of colitis and was RX'd this and Cipro 500mg 2X a day. The flagyl is so rough on me. It makes my stomach hurt so badly, as if I had pancreatitis.  I also started running a temperature and felt like I had bronchial pneumonia. I am very limited on the antibiotics I can take due to allergies. I won't take this antibiotic again unless I'm in dire straights. I can't take levaquin because it causes me to get pancreatitis and tendinitis. I've read that flagyl gets rid of parasites. I hope if I have them that they're gone after taking the flagyl 3X a day for 10 days......"