A Jarisch-Herxheimer reaction, shortened to “herx” as slang, is a predictable and temporary “flare-up” or worsening of symptoms caused by the die-off of spirochete bacteria. This condition was discovered and named after the German dermatologist, Karl Herxheimer (1844-1947). The condition was originally observed in syphilis patients. This recurring flare up is physically and emotionally devastating – especially for those who have very chronic and/or severe cases of chronic Lyme disease.
