The Herxheimer reaction is an inflammatory process that occurs inside the body when large numbers of bacteria die and release toxins. This reaction can be observed in people with certain types of infections who are taking antibiotics for treatment and become sicker for a brief period of time as the body processes the toxins. Herxing, as it is sometimes known, is not necessarily dangerous to the patient's health, but it can be uncomfortable, and it may make it difficult for a patient to comply with a drug regimen. There are drugs available to reduce the inflammation.
This phenomenon, also known as the Herx reaction, die-off reaction, or Jarish-Herxheimer reaction, was first observed at the turn of the 20th century in syphilis patients. Dermatologists treating such patients noticed that when initially dosed with medication to treat the bacterial infection, these patients developed flu-like symptoms like fever, chills, muscle pains, and headaches. The lesions on the surface of the skin caused by the infection also grew worse.
Physicians realized that killing off bacteria in large numbers resulted in a flood of bacterial toxins in the system. The body can cope with toxins in low concentrations, but is not equipped to handle a high volume, and consequently, patients would get sick until the body could successfully clear the toxins. The Herxheimer reaction could be viewed as a sign the treatment was actually working by killing off the bacteria.
Spirochete bacteria like those seen in syphilis and Lyme disease are most commonly associated with a Herxheimer reaction, although such reactions can be triggered by other organisms as well. Patients undergoing antibiotic treatment for conditions commonly linked with a Herxheimer reaction may be warned ahead of time that they could experience a brief period of illness after taking antibiotics. It is important to be aware that once recovered, the antibiotics still need to be continued, to kill off any bacteria lingering in the body. Stopping antibiotic treatment before the course is finished will allow some organisms to remain.
Antiinflammatory drugs can be used to reduce the inflammation associated with the bacterial toxins and these drugs may be prescribed to patients when they experience severe symptoms. Patients may also be advised to rest and stay hydrated while the Herxheimer reaction resolves. People who need to take repeated rounds of antibiotics for recurrent disease may be familiar with this side effect and should take note if they respond differently to antibiotics than usual.