Action vs Reaction

This document is for informational purpose only.


 Action vs Reaction

By Frank Clark R.Ph.

Through my many hours of reading and research on this subject, I have never found a document that says it all better than this one. It is unchanged from its original publication. My comments appear underlined. Of special importance to pharmacists like myself is the observation that herxheimer reactions often mimic allergic reactions. Many of our patients with an “allergic” reaction to one antibiotic go on to experience many more such reactions with many other different antibiotics. The result is a dwindling selection of antibiotics with which to treat these patients for infections. Many of these patients were later diagnosed with Lyme disease and subsequent challenge with an “allergy-inducing” antibiotic did not provoke an allergic reaction.


Lyme Disease

What is a Herxheimer Reaction?

By Donna Herrell
Director, Lyme Alliance Inc.

The herxheimer reaction, nicknamed “herx” or otherwise referred to as Jarisch- Herxheimer (J-H) is a phenomena originally observed in the treatment of syphilis, but later found in other illness. In general terms, it is described as a temporary increase of symptoms when anti-syphilitic drugs (antibiotics) are administered or the subject’s body temperature is raised to @103 degrees F regardless of the means (sauna, fever exercise or environmental heat exposure) as spirochetes die at this body temperature.  What is known or speculated about Lyme disease herxheimers is based heavily on the reactions seen in syphilis. This is due to the fact both diseases are caused by a bacteria known as a spirochete, the former being Treponema pallidum, the latter Borrelia burgdoferi (B.b). However the herxheimer reactions in Lyme disease are not identical to those seen in syphilis, especially in terms of timing, frequency and duration as noted below.

In Lyme disease it is thought that the cause of herxheimers are the result of endotoxin release, that is toxin(s) within the spirochete that are released as the
B.b are killed or broken down. This may be a result of the toxin(s) itself or the body’s immune response to such.
Anecdotal evidence suggests that 80% of patients experience this reaction within 3 days of starting antibiotics or having achieved elevated body temperatures @103 degrees F.


As mentioned, the general description is a temporary increase in symptoms, but also
included is the development of new ones. More specifically the most common events
include: increased joint or muscle pain, headaches, chills, fever (usually low grade),
drop in blood pressure, hives and rash. A multitude of other symptoms have been

Worth noting is that hives and rash are sometimes mistaken for an allergic reaction. Especially since many allergic reactions occur within 3 days like the herxheimer reactions do. It is up to one’s physician to determine this, but with close observation and the use of medications such as Benedryl often prevents stopping antibiotics prematurely. In more severe cases of J-H a reduction of the dosage or temporarily cessation of the treatment is an alternative. Great care must be taken to distinguish allergic reaction symptoms from those of a herxheimer reaction for the following considerations. If it is a herxheimer reaction then the antibiotic is successfully treating the Lyme disease infection and should be continued as long as it is deemed necessary to achieve completely successful treatment. If, instead, an allergic reaction to the antibiotic is evident then the antibiotic should be stopped and replaced with one that does not illicit an allergic reaction and an allergy to the offending antibiotic should be noted on the patient’s profile at the doctor’s office and pharmacy. Assume that all reactions are allergic in nature and the patient will be precluded from proper treatment of Lyme disease AND further use of an ever growing list of innocent and important classes of antibiotics merely because those antibiotics were successfully fighting lyme spirochetes. Assume that all reactions are herxheimer reactions and you run the risk of exposing the patient to anaphylactic shock by continuing therapy with an antibiotic that they are allergic to.  

Timing, Frequency and Duration:

This is individualistic and Herxheimer can occur within days to weeks after the onset of antibiotic therapy. In some patients they occur only once or twice (if at all) and with others continue throughout the course of treatment, usually lessening in severity. They can occur and are more often described in cycles (example: every 4 weeks) and have been reported to last from days to weeks. It can be very beneficial to document these exacerbations. Some physicians use this as a guideline for treatment. Further it may help differentiate herxheimers from the normal symptoms or progression of Lyme disease.


Herxheimer reactions can be very difficult on patients and affect compliance with therapy so supportive measures should be sought or utilized to lessen discomfort if needed. The use of aspirin, NSAIDs (non steroidal anti inflammatory drugs), pain medication, muscle relaxers, hot baths or others remedies can be appropriate. Of note, some have found Benedryl helpful even in the absence of rash or hives. There is reason to believe that the liver becomes congested in its attempts to clean the bloodstream of the spirochetal endotoxin. Support for the liver may lessen the intensity of the herxheimer reaction. Drinking lots of clean filtered water, with lemon juice added and taking liver support herbs like milk thistle, Jerusalem artichoke, licorice and dandelion root is recommended. Of all of these, it has been my experience that milk thistle is, by far, the most important. ThistlRx is a product commercially available that has all of these ingredients and provides spectacular benefits for patients with all manner of liver diseases such as hepatitis B, hepatitis C and cirrhosis.

The good news is that the herxheimer is thought to indicate that the antibiotics are indeed working and that following each worsening may bring about more improvement. However the lack of herxheimer reaction should not cause anxiety if symptoms are improving.

Other considerations:

Something often overlooked but can present with similar symptoms as a herxheimer is Candida (yeast) infection. Treatment with acidophilus and if needed prescription medications such as Nystatin or Diflucan can be utilized.


So how do you know if the reaction is an allergic reaction or herxheimer reaction? Allergy testing for the “offending” antibiotic would be a good start. If the allergy testing comes up negative for the antibiotic then chances are it is a herxheimer reaction. Be aware that allergies to antibiotics or any other antigen can change over time. Let your doctor be the judge.

Sources of Information:

1) Lyme Disease 1991 – Patient/Physician Perspectives from the U.S. and CanadaThe Jarisch-Herxheimer Reaction
    James H. Katzel M.D.
2) Managing Lyme Disease (1996)
    Joseph J Burrascanno M.D.
3) Principles and Practice of Infectious Diseases 4th Ed.
    Mandell, Douglas and Bennett
4) Seronegative chronic relapsing neuroborreliosis.
    Lawrence C, Lipton RB, Lowy FD, Coyle PK
    Eur Neurol 1995;35(2):113-117





%d bloggers like this: