If i've taken macrobid for uti in the past with no reaction how worried should i be now that i might have an allergic reaction?

Dont worry: If you had no reaction in the past , you will likely be O.K..It is still possible to have an allergic reaction at any time, but the fact that we know you are not allergic to this medicine, is a good predictor.

Allergies unusual: Macrobid is usually very well tolerated with a very low rate of allergic reactions. The other common medications used to treat bladder infections (such as sulfa or cephalosporins) are much more likely to cause an allergic response. If you have concerning symptoms such as an unusual rash or trouble breathing you should review these problems with your doctor.

Don't worry: Be happy. You can't worry over developing an allergic reaction to a drug since it is usually unpredictable however if one already is allergic to one drug (not intolerance), he is more likely to develop allergy to another.