Ive been on keflex 6 days. last night i had a hive about the size of a dime on left breast. i took 2 benadryl and its almost gone this morning. could keflex cause 1 hive? should i finish the last dose? or skip it? am i now allergic to keflex?

Cannot tell for sure: It is possible to be allergic to any medication. A medication has other ingredients, such as stabilizers, preservatives, pH buffers, etc..., and a person may be allergic to one of the other ingredients. Also, a person can be ok with the drug, but react to a breakdown product of the drug, or react to a "bound" combination of the drug+substance (the substance may be from the person's own body).