Clindamycin
"This drug did what it was supposed to do in preventing an infection in a puncture wound in my foot.
However on the 9th day of taking this drug I had an allergic reaction. Dose was 300MG 4 x's per day for 10 days. 
Hives broke out from my chest down to my upper thighs. My doctor told me to take Zyrtec or Claritin and should clear up the rash/hives in 2-3 days. "