In such cases, the kidneys may not be able to eliminate antibiotics from the body as effectively, increasing the risk of side effects. Doctors also consider the following:
http://www.merck.com/mmhe/sec17/ch192/ch192a.html
Antibiotics may also sometimes be administered topically, as with eye drops or ointments. Side effects. Although antibiotics are generally considered safe and well tolerated, they ...
http://en.wikipedia.org/wiki/Antibiotic
Not only do the antibiotics kill the bacteria causing the ear infection, but they also kill the friendly bacteria, called "flora", that live in your child's intestines.
http://www.askdrsears.com/html/8/T080600.asp
Antibiotics may have side effects. Some of the more common side effects may include: Soft stools or diarrhea; Mild stomach upset; You should notify your doctor if you have any of the ...
http://www.emedicinehealth.com/antibiotics/page4_em.htm