drug reaction

[gopo92]

can a person get drug reaction like anaphylactic reaction even if the drug has been used before. e.g if I have taken a particular antibiotic many times, is there still a chance that I might get a reaction to it????

[achillea]

Yes, it is possible.  Happens all the time, in fact.  You hear people say, 'But I have taken X for years and never had a problem,' but there's a good physiological reason for why it does happen:

Immune reactions and allergies--almost without exception--require *prior exposure* to something.  IOW, the immune system has to be acquainted with a substance in order to react to it and make antibodies.  That's the essential nature of immunity.

The mystery is *why*, after tolerating something like a medication, a food, or even a cosmetic for years, the immune system actually makes a mistake and decides the substance is a bad guy after all.  

For more information, check out this site, especially the paragraph titled "What causes allergies to start?":

http://www.webmd.com/allergies/guide/chronic-allergies-causes

[Jerry_NJ]

I believe the answer is unlikely but possible.  One should always be on the outlook for unusual side effect symptoms.  

I have several heart drugs that I have taken for years and I am always on guard and on the outlook for signs of symptoms or increases in symptoms problems.

I do not take antibiotic often, but I have never had any side effects or reactions that I could detect.