I was taking cefdinir for a sinus infection. Eight days into a 10-day treatment, I got a very bad case of hives (my doctor said it's not abnormal for the reaction to take so long to show up).

The hives were EVERYWHERE and I couldn't do much for several days. Antihistamines didn't help so I used cortisone cream to deal with it. It was just constant itching.

It has now been two and a half weeks since the episode and the hives have GREATLY reduced. I take 1 claritin a day and I'm mostly hive free, but when I go off the claritin the hives return to an annoying but not serious level.

How long can it take for it go away, assuming the antibiotic was the agent that caused it and I stopped taking it?

Thanks!

Cableboy just a guess here. In our family we have noticed a connection between our normal flora in our gut and our allergies. There is a lot of info on the net about this stuff. Your immune cells are in your gut and if your gut is healthy your immune system works better (allergies are an immune system gone awry). Antibiotics mess up your normal flora and maybe this is what has happened to you. Maybe you were borderline allergic or something and the antibiotic messing up your normal flora might have pushed you over the edge? Cure? Eat some yogurt everyday and see if you improve. The acidophilus in the yogurt will improve your normal flora.

Some things take longer than others to get out of the system. It should be clear within 6 weeks.

Hives usually come from the inside out, this means your body may still be saturated with the antibiotic. Some antibiotics continue to work for 2 weeks after he completion of taking it, then additional time will be needed for the antibiotic to be flushed out of your system.

Have you checked the internet to find out the half-life of the antibiotic?