A Jarisch-Herxheimer Reaction (often called a Herx for short) is the reaction that your body gets when there is a spike in die offs from the Lyme Disease and associated co-infection bacteria. It is sometimes seen as a good sign (that the medication is working), however severe Herxes can be dangerous (causing brain and organ damaged) and so need to be managed carefully. You can read more about the Herx reaction here - http://whatislyme.com/the-herxheimer-reaction/ and ways to manage a herx reaction can be seen here and http://www.lyme-disease-research-database.com/coping_with_a_herx.html here – http://whatislyme.com/biotoxin-illness-and-detoxing/ but the most important thing is to let your body rest and recover and not place too much extra stress on your body.
Some Lyme doctors recommend a special drink to ease mild herx reactions – you can read about this here.
Because Herx reactions to treatment for Lyme Disease and associated coinfections can be dangerous, the LDAA recommends you work with an experienced Lyme Disease doctor to guide your treatment, rather than self treating from information that you have sourced off the internet.