Jarisch-Herxheimer reaction
noun
Ja·risch-Herx·hei·mer reaction
ˈyä-rish-ˈherks-ˌhī-mər- 
: an increase in the symptoms of a spirochetal disease (as syphilis, Lyme disease, or relapsing fever) occurring in some persons when treatment with spirocheticidal drugs is started
called also Herxheimer reaction
Cite this Entry
“Jarisch-Herxheimer reaction.” Merriam-Webster.com Medical Dictionary, Merriam-Webster, https://www.merriam-webster.com/medical/Jarisch-Herxheimer%20reaction. Accessed 4 Nov. 2025.
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