What are the treatment options for a patient who experiences shivering immediately after a penicillin injection?

Immediate Management of Shivering After Penicillin Injection

Stop the injection immediately and assess for anaphylaxis—shivering may represent the early phase of a systemic allergic reaction requiring emergency intervention with epinephrine, oxygen, IV steroids, and airway management. 1

Initial Assessment and Emergency Response

The immediate priority is determining whether shivering represents:

• Anaphylaxis or severe hypersensitivity: Look for accompanying symptoms including urticaria, angioedema, upper airway obstruction, bronchospasm, hypotension, tachycardia, or cardiac symptoms 2, 1
• Vasovagal reaction: May present with pallor, diaphoresis, hypotension, and bradycardia (rather than tachycardia) 1
• Jarisch-Herxheimer reaction: Occurs specifically in syphilis treatment, typically manifesting as fever, chills, and myalgias 1

Emergency Treatment Protocol

If any signs of anaphylaxis are present:

• Administer epinephrine immediately (0.3-0.5 mg IM in adults) as the first-line treatment 1
• Provide supplemental oxygen and establish IV access 1
• Administer IV corticosteroids and antihistamines as adjunctive therapy 1
• Prepare for airway management including intubation if needed 1
• Monitor continuously for cardiovascular collapse, cardiac arrest, or pulmonary complications 1

Risk Stratification Based on Reaction Type

Immediate hypersensitivity reactions (occurring within minutes to 1 hour):

• These are IgE-mediated and carry the highest risk of anaphylaxis and death 2
• Penicillin is the leading cause of drug-induced anaphylaxis and accounts for approximately 500 deaths annually in the United States 3
• Symptoms include urticaria, angioedema, bronchospasm, hypotension, and cardiovascular collapse 2, 1

Kounis syndrome (acute myocardial ischemia as part of allergic reaction):

• May occur with penicillin hypersensitivity and presents with cardiac symptoms alongside allergic manifestations 1
• Requires immediate cardiac monitoring and management

Post-Acute Management and Documentation

Once the patient is stabilized:

• Document this reaction thoroughly as a confirmed penicillin allergy in the medical record 2
• Note the specific penicillin formulation, route of administration, timing of reaction, and all symptoms 4
• Discontinue penicillin therapy immediately unless the condition is life-threatening and amenable only to penicillin 1

Future Penicillin Use Considerations

If penicillin is absolutely required in the future (no suitable alternatives):

• Perform formal allergy testing with both major determinant (benzylpenicilloyl poly-L-lysine) and minor determinants before any re-exposure 2
• Skin testing has a negative predictive value approaching 100% for identifying patients at risk of severe reactions 2
• Testing should be performed in a monitored setting with immediate access to anaphylaxis treatment 2

For patients with positive skin tests requiring penicillin:

• Desensitization is the only option and must be performed in a hospital setting 2
• Oral desensitization is safer and easier than IV desensitization 2, 5
• The procedure typically takes approximately 4 hours to complete 2
• In one study of 30 penicillin-allergic patients undergoing oral desensitization, no deaths, anaphylaxis, or severe acute reactions occurred, though 30% developed pruritic rashes 6-48 hours after therapy 5

Critical Pitfalls to Avoid

• Never dismiss shivering as benign without ruling out systemic hypersensitivity—it may be the first sign of impending anaphylaxis 1
• Do not rely on antihistamines alone for treatment if anaphylaxis is suspected; epinephrine is the only appropriate first-line therapy 1
• Avoid re-challenging with penicillin without proper allergy evaluation, as subsequent reactions can be more severe 2, 4
• Do not assume cross-reactivity with all beta-lactams is absolute; aztreonam is the only beta-lactam that may be safely used in penicillin-allergic patients 3

Alternative Antibiotics

For future infections requiring antibiotic therapy:

• Select alternative antibiotics with unrelated chemical structures when possible 6
• Consider cross-reactivity patterns: cephalosporins have variable cross-reactivity (1-10%) depending on side-chain similarity 6
• Aztreonam (a monobactam) does not cross-react with penicillins and is safe in penicillin-allergic patients 3