Allergic Reaction to Amoxicillin: Here's Some Information That You May Need

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What Is Amoxicillin And What Happens During An Amoxicillin Allergic Reaction?

Amoxicillin is an antibiotic which belongs to the penicillin family of antibiotics and which is useful for treating many commonly seen bacterial infections, including those that affect the skin, ears and the upper respiratory system. For many people, amoxicillin is a benign drug that causes no or minor side effects. Some people, however, cannot tolerate this antibiotic and have an allergic reaction to it whenever it is ingested. In such a reaction, the immune systems of these people essentially “go haywire” and erroneously produce immunoglobulin antibodies that fight this antibiotic.

This immune response to amoxicillin by the body often produces harmful side effects, which include, for example, wheezing, rash, hives, and swollen skin (especially in the facial area). In rare but severe cases, individuals having an allergic reaction to amoxicillin can experience a life-threatening condition known as anaphylaxis, which is a whole body response that features serious symptoms such as difficulty in breathing, severe mouth and throat swelling, drop in blood pressure and even loss of consciousness. Needless to say, a person experiencing anaphylaxis requires immediate professional medical attention.

How Is An Allergy To Amoxicillin Diagnosed And What Can Be Done To Treat And Prevent An Amoxicillin Allergic Reaction?

Symptoms of an allergic reaction can be treated using an antihistamine, which blocks the normal activity of histamine molecules needed for the immune system to generate an allergic response. A common antihistamine that is used for this purpose is Benadryl (diphenhydramine). For skin conditions, such as rashes, itching, and hives, for example, a topical antihistamine (Benadryl is offered in cream form) can be applied directly to the skin to remedy the condition.

If you know that you are allergic to penicillin, you should make your doctor aware of this fact because he/she likely will either choose to avoid prescribing amoxicillin or will at least want to test you for an amoxicillin allergy before prescribing this drug. The common way to test for an allergy to amoxicillin is to administer a skin test (you can read about allergy skin tests here).

How Is An Allergy To Amoxicillin Diagnosed And What Can Be Done To Treat And Prevent An Amoxicillin Allergic Reaction? (Continued)

If you prove to be positive for allergy to amoxicillin, your doctor will select an alternative antibiotic, and likely one that does not belong to the penicillin family, for treating your bacterial infection.

If you learn that you are in fact allergic to amoxicillin, you should wear an emergency bracelet that indicates your allergy. This is true because drugs in the penicillin group are sometimes given in emergency situations to accident victims who are unconscious or otherwise unable to express to medical personnel that they are allergic to amoxicillin. While there is no good time to have an allergic reaction, such a reaction is especially problematic when medical personnel are treating an individual for other serious injuries as the allergic reaction only further threatens the patient’s overall condition.

If you are allergic to amoxicillin and a your bacterial infection is not responding to any other antibiotic, your doctor may choose to try to desensitize you to amoxicillin in hopes that your immune system can be “taught” to resist fighting this drug. In a typical desensitization process, a doctor will first introduce amoxicillin in a very small amount to a person trying to overcome allergy to it. If that small amount does not cause an allergic response, the doctor will give a second, slightly larger dose to see whether the person can tolerate the second dose. This process will be repeated, and perhaps several times over the course of many days, until either an allergic response is experienced or a therapeutically effective amount of the drug (that is, enough of it to ward off the bacterial infection) is tolerated by the patient.

This article is only meant to provide some basic information regarding amoxicillin allergies. If you believe that you may be experiencing an allergic reaction to amoxicillin or you are interested in learning more about this problem, please do not hesitate to contact your family doctor.


Mayo Clinic, Penicillin Allergy:

Medline Plus, National Institutes of Health, Drug Allergies:

M.E. Pichichero and D.M. Pichichero, Diagnosis of penicillin, amoxicillin, and cephalosporin allergy: reliability of examination assessed by skin testing and oral challenge, Journal of Pediatrics 132:137-143 (1998).