Cefdinir
"I have chronic sinusitis and was prescribed cefdinir. I had no known allergies to antibiotics (and have been on MANY over the years) Two days into treatment I woke with my face swollen and covered in hives. My throat began swelling and I was rushed to the ER. After two Epi shots and IV epinephrine, I spent 5 days in intensive care with anaphylaxis and the worst case of hives I have ever experienced. It was, by far, the most agonizing pain I've endured. It took months to go away with steroids, antibiotics and prescription antihistamines. It have permanent scarring on my body as a result of the hives. I'm now allergic to all cephalosporins."