What is Penicillin and other antibiotic allergy

Penicillin allergy and other other antibiotic allergies are not diseases on their own, but the clinical situations commonly encountered in medicine are due to adverse drug reactions.

As the name suggests, it is an allergic or hypersensitivity reaction towards penicillin or other antibiotics.It can occur in many parts of the body as in any allergic reaction. However the commonly affected parts are:

  • skin
  • airways
  • gut
  • face
  • generalised

Statistics on Penicillin and other antibiotic allergy

Penicillin allergy and other antibiotic allergy are considered as adverse drug reaction. Drug reactions are responsible for 2-5% of hospital admissionis in the US. From these data alone they are considered to be common in hospital practice.

Risk Factors for Penicillin and other antibiotic allergy

Penicillin allergy can happen in anyone of any age. However, higher incidence of adverse drug reactions is found in females when compared to males. Although penicillin allergy can happen in any age, it is suspected that elderly patients have increased incidence of this clinical entity. This may be due to higher cases of diagnosis as compared to young adults.

Progression of Penicillin and other antibiotic allergy

Penicillin administration can cause allergic reactions through several mechanisms. Generally it can cause all types of hypersensitivity reactions, including type I, II, III and IV (see Introduction to Allergy and Hypersensitivity).
Usually penicillin allergy occurs within 1 hour of drug administration. However, sometimes it can take longer. Other antibiotics of the same group (beta-lactams) like amoxycillin can produce allergic reactions unpredictably regarding the duration of allergy development.

How is Penicillin and other antibiotic allergy Diagnosed?

Clinical history and examination are sufficient in diagnosing most cases of penicillin and other antibiotic allergy. However, if the patients are to be admitted due to increased severity of the reactions, routine tests may be done to look at the blood function, liver function, kidney function, blood electrolytes and degree of oxygenation in the blood.
These tests may be abnormal if the reaction is severe. Hence, they provide insight into disease severity, and are useful for monitoring the effectiveness of treatment.

Prognosis of Penicillin and other antibiotic allergy

The most severe form of penicillin or other antibiotic allergy is anaphylactic reaction. If left untreated, this can be life-threatening, hence denoting that this is a medical emergency. Also with angioedema, if the allergic reaction leads to airway obstruction, this can be life-threatening as well.
However most of the allergic reactions are self-limited once the offending agent (penicillin or other suspected antibiotics) is ceased. They are not life-threatening but can cause significant distress to the patient.

How is Penicillin and other antibiotic allergy Treated?

The treatment overview for anaphylactic reaction and angioedema is discussed elsewhere.
The mainstay of treatment option is penicillin or other antibiotic avoidance if they are suspected to cause allergic reactions. Allergic reactions to penicillin may mean that the patients are allergic to other antibiotics of the same group (called beta-lactams), such amoxycillin, ampicillin, flucloxacillin, dicloxacillin, etc. Other precautionary measures include informing any healthcare professionals regarding this, wearing a bracelet, writing in the card, etc.
If the patient known or suspected to have penicillin allergy and needs to take this antibiotic for certain infections, desensitization can be done. This involves exposing the patient to increasing doses of penicillin orally or through infusion of the drug into the veins. Each hospital would have their own protocols on desensitization. However, most desensitization are done in approximately 3.5 hours. Desensitization may cause an anaphylactic reaction, hence this procedure needs to be done under controlled situation in the hospital.

Penicillin and other antibiotic allergy References

  1. Anderson, JA. Allergic reactions to drugs and biological agents. JAMA 1992; 268:2844.
  2. Bates, DW, Cullen, DJ, Laird, N, et al. Incidence of adverse drug events and potential adverse drug events. Implications for prevention. JAMA 1995; 274:29.
  3. Borish, AL, Tamit, R, Rosenwasser, LJ. Intravenous desensitization to beta-lactam antibiotics. J Allergy Clin Immunol 1987; 80:314.
  4. eMedicine: Drug eruptions [online]. 2004. [Cited 2005 October 19th]. Available from: URL: http://www.emedicine.com/derm/topic104.htm
  5. Sullivan, TJ, et al. Desensitization of patients allergic to penicillin using orally administered B-lactam antibiotics. J Allergy Clin Immunol 1982; 69:275.
  6. Up to Date: Penicillin and other antibiotic allergy; skin testing; and desensitization [online]. 2004. [Cited 2005 October 19th]. Available from: URL: http://www.utdol.com/application/topic.asp?file=allergy/7562&type=A&selectedTitle=1~30

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