From the Guidelines
Before administering cephalosporin antibiotics, healthcare providers should thoroughly assess the patient's allergy history, particularly asking about previous reactions to cephalosporins, penicillins, or other beta-lactam antibiotics. Patients should be specifically questioned about the nature of any previous reactions, as true allergies involve immune-mediated responses like hives, angioedema, or anaphylaxis. For patients with documented severe allergic reactions to penicillins, caution is warranted due to potential cross-reactivity between penicillins and cephalosporins, especially first-generation cephalosporins 1. If the patient reports a penicillin allergy, determine the severity and timing of the reaction; mild reactions may not contraindicate cephalosporin use. For high-risk patients, skin testing may be considered before administration, as recommended in the 2022 practice parameter update on drug allergy 1. When administering the first dose, ensure emergency medications (epinephrine, antihistamines, corticosteroids) and resuscitation equipment are readily available. Start with a test dose in some cases, and monitor the patient closely for 30 minutes after administration for signs of allergic reaction such as rash, itching, respiratory difficulty, or hypotension. Patient education about recognizing and reporting allergic symptoms is also essential. It's also important to note that the cross-reactivity between penicillins and cephalosporins is lower than historically reported, and the risk of cross-reactivity is higher between penicillins and first-generation cephalosporins but is negligible with the second- and third-generation cephalosporins 1. The use of cefazolin, a first-generation cephalosporin with a unique side chain, has been shown to have very low cross-reactivity with penicillins 1. In patients with a history of anaphylaxis to cephalosporins, penicillin skin testing and drug challenge should be performed prior to administration of a penicillin therapy, as suggested by the 2022 practice parameter update on drug allergy 1. Overall, a thorough assessment of the patient's allergy history and careful consideration of the potential risks and benefits of cephalosporin use are necessary to minimize the risk of allergic reactions.
From the Research
Precautions Before Administering Cephalosporin
To prevent an allergic reaction when administering cephalosporin, several precautions should be taken:
- Assess the patient's history of penicillin allergy, as patients with a history of penicillin allergy may be at increased risk of adverse drug reactions to cephalosporin 2, 3, 4.
- Consider penicillin skin testing if cephalosporin, especially a first-generation cephalosporin, is to be administered to patients with a history of penicillin allergy 2.
- Be aware that the risk of cross-reactivity between penicillins and cephalosporins is lower than previously reported, and the R1 side chain is responsible for this cross-reactivity 5, 4.
- Note that the overall cross-reactivity rate between penicillins and cephalosporins is approximately 1% when using first-generation cephalosporins or cephalosporins with similar R1 side chains 4.
- Consider using third- or fourth-generation cephalosporins or cephalosporins with dissimilar side chains than the offending penicillin, as they carry a negligible risk of cross allergy 4.
Key Considerations
- The chemical structure of cephalosporins, particularly the side chain, plays a crucial role in determining the specificity of immunologic reactions 6, 5.
- Skin testing to the cephalosporin in question can provide additional information to guide the work-up of a patient suspected of having an allergy to that drug 6.
- The incidence of adverse reactions to cephalosporins in patients with a history of penicillin allergy is minimally increased, if at all 3.