... nearly 2 years. I have been given cefalexin for a dental abscess ( I am allergic to penicillin) and I see it can cause hemolytic anemia. Naturally I am very worried about the antibiotic starting up the anemia again. Does this mean I should not take it? Does the anemia, if it is started by the drug, only last till it is out of your system? Any advice would be very much appreciated