There is a BIG difference between an ALLERGIC reaction to an antibiotic and an ADVERSE reaction. An allergic reaction is generally short term in nature like a rash, labored breathing, etc. Adverse reactions are usually much longer lasting (can be permanent) and typically much more severe. Herxing symptoms as described on this board can be exactly like adverse reactions to an antibiotic. It would be impossible to tell the difference between diarrhea, nausea, malaise, fever, etc. caused by herxing from the same symptoms caused by an adverse reaction. The herxing will go away, but the adverse reaction could be the harbinger of much worse problems that could be permanent. Beware of all the talk of herxing as if it in a minor annoyance on the way to getting better. The symptoms you are experiencing could be the result of an adverse reaction to the drug you are taking and you might be much worse off than when you began taking the drug. Remember, allergic reactions are generally self limiting. Adverse reactions are not--examples are ulcerative colitis (abx), joint damage (abx), heart damage (antiinflammatories and abx), nerve damage (abx), liver damage (all drugs), etc. Be careful before ingesting any drug for long periods of time.