The Herx Reaction

The herx reaction is expected during treatment. However moderate herxing might not be tolerated and treatment may need to be modified 
or slowed down. Severe herxing can in fact be very detrimental, and has even been known to be fatal. A balance is therefor required. Quite 
literally the degree of herxing is proportional to the bacterial kill. It is caused by breakdown products of the dying bacteria. It certainly will 
cause raised discomfort for a few days or even several during treatment. 

The reaction can be thought of as temporary flu like symptoms combined with the individuals own unique disease symptoms. Ask about ways 
to help alleviate these problems.

The herx reaction differs in frequency for bartonella, babesia and lyme. It may cause a rash and great confusion can occur compared to the 
possibility of allergic drug reaction. The rashes are very different with the latter being urticarial.

Here is a picture of a bartonella rash that comes up during herx reactions in an 8 yo girl. Note the classic tell-tale bartonella striae.

and after two months treatment on her new antibiotic improvement was obvious with just this much rash on the left buttock

For the technically minded Wikipedia has an excellent few words to say at