Clindamycin
"I had a sinus infection that wouldn't go away with other antibiotics and I'm allergic to so many of the other strong ones that this is what I ended up being prescribed. I was worried about bad side effects because of my standing allergies, but it's really not all that bad. I started feeling better after the first day and I didn't have any side effects at first. It's day 6 of a 10 day treatment and I have a terribly sore throat but that's the only bad side effect I've noticed besides some soreness and mild nausea if I don't eat much. Note that I take a probiotic everyday, eat before each pill and drink a full bottle of water. I also don't lie down for at least 30 minutes after taking it. I'll try to stick out the full 10 days."