Got hives from amoxicillin allergy - do I need to do anything?

Tell your doctor. Drug reactions such as hives may represent an allergic reaction to a medication, or sometimes a cross reaction to a virus. In any case, you should discuss this with your health care provider to add this medication to your list of potential allergies.
Take antihistamine. If you are still reacting take an antihistamine. You should not take it again.