Alternative Antibiotics for Patients with Antibiotic Allergies
For patients with antibiotic allergies, alternative antibiotics can be safely selected based on the type of allergic reaction, its severity, and the time elapsed since the reaction, with specific recommendations varying by antibiotic class.
Assessment of Antibiotic Allergies
- A detailed allergy history should always be performed and critically appraised to determine if a true allergy exists, as less than 10% of patients with an antibiotic allergy label are truly allergic 1
- Key information to collect includes:
- Date of occurrence
- Nature, intensity, onset, and duration of symptoms
- Whether the reaction was immediate (within hours) or delayed (days)
- Severity of the reaction 1
Alternative Options for Penicillin Allergies
For Immediate-Type Penicillin Allergies:
- Cefazolin can be safely used in patients with suspected immediate-type allergy to penicillin, regardless of severity or time since reaction, as it does not share side chains with available penicillins 1
- Patients with non-severe immediate-type reactions to penicillin that occurred >5 years ago can receive cephalosporins with similar side chains in a controlled setting 1
- Monobactams and carbapenems can be administered to patients with immediate-type penicillin allergy without prior allergy testing 1
- Erythromycin is a suitable alternative for patients with penicillin allergy, particularly for mild infections 1
For Delayed-Type Penicillin Allergies:
- For non-severe delayed-type allergies that occurred <1 year ago, all other penicillins should be avoided 1
- For non-severe delayed-type allergies that occurred >1 year ago, other penicillins can be used 1
- Cephalosporins with dissimilar side chains can be administered to patients with non-severe delayed-type penicillin allergies, regardless of when the reaction occurred 1
- Cephalosporins with similar side chains (e.g., cefalexin, cefaclor, cefamandole) should be avoided in patients with delayed-type allergy to amoxicillin, penicillin G, V, or piperacillin 1
Cross-Reactivity Considerations
- The cross-reactivity between penicillins and second- or third-generation cephalosporins (excluding cefamandole) is likely no higher than between penicillins and other antibiotic classes 2
- Cross-reactivity between different cephalosporins is dependent on R1 side chain similarity 1
- Ceftazidime, cefiderocol, and aztreonam share an identical side chain, resulting in higher cross-reactivity risk 1
Management of Multiple Antibiotic Allergies
- For patients with allergies to multiple beta-lactam antibiotics (penicillins, cephalosporins, and carbapenems), guidelines recommend avoiding all beta-lactam antibiotics in cases of suspected severe delayed-type allergies 3
- Aminoglycosides (e.g., gentamicin) may be an option for patients with multiple beta-lactam allergies 3
- For severe infections where alternative antibiotics may be less effective, consultation with an infectious disease specialist and allergist for potential desensitization should be considered 3
Special Considerations
- Sulfonamide allergies do not preclude the use of cephalosporins, as there is minimal cross-reactivity between these classes 4
- For patients with severe infections and limited antibiotic options due to allergies, desensitization therapy should be considered 2
- Penicillin skin testing has excellent sensitivity for predicting serious allergic reactions and can help identify patients who lack penicillin-specific IgE antibodies 2, 5
Common Pitfalls to Avoid
- Overestimating cross-reactivity between penicillins and cephalosporins, leading to unnecessary avoidance of effective antibiotics 1
- Failing to distinguish between true allergies and drug intolerances or idiosyncratic reactions 6
- Not considering the time elapsed since the allergic reaction, which can affect the risk of recurrence 1
- Automatically selecting broad-spectrum antibiotics for patients with reported allergies without proper assessment 5