How to manage an injection site reaction?

Management of Injection Site Reactions

For injection site reactions, management should be based on severity, with mild to moderate reactions treated with cold compresses, antihistamines, and topical corticosteroids, while severe reactions require immediate medical attention including epinephrine administration for anaphylaxis. 1

Assessment and Classification

Injection site reactions should be classified based on severity:

• Mild to Moderate Local Reactions:

  • Symptoms: Erythema, swelling, pruritus, and pain around the injection site
  • Usually self-limiting and resolve within hours to days

• Severe Reactions/Anaphylaxis:

  • Symptoms: Systemic symptoms affecting airway, breathing, circulation, or consciousness
  • Medical emergency requiring immediate intervention

Management Algorithm

For Mild to Moderate Reactions:

1. Stop medication administration if still being administered 2
2. Apply cold compresses to reduce swelling and discomfort 1
3. Administer antihistamines:
   • H1 antagonists: Diphenhydramine 25-50 mg orally or IV
   • H2 antagonists: Ranitidine 50 mg IV 2
4. Apply topical corticosteroids for pruritus and inflammation 1
5. Monitor vital signs until resolution 2

For Severe Reactions/Anaphylaxis:

1. Stop medication administration immediately 2
2. Maintain IV access and assess ABCs (Airway, Breathing, Circulation) 2
3. Position patient appropriately:
   • Trendelenburg position for hypotension
   • Sitting up for respiratory distress
   • Recovery position if unconscious 2
4. Administer epinephrine if anaphylaxis criteria are met:
   • Dose: 0.2-0.5 mg (1 mg/mL) IM into lateral thigh
   • Repeat every 5-15 minutes if needed 2
5. Initiate fluid resuscitation:
   • 1-2 liters of normal saline at 5-10 mL/kg in first 5 minutes
   • Crystalloids or colloids in boluses of 20 mL/kg, followed by slow infusion 2
6. Administer antihistamines:
   • Diphenhydramine 50 mg IV plus ranitidine 50 mg IV 2
7. For bradycardia: Atropine 600 μg IV 2
8. For persistent hypotension:
   • Dopamine (400 mg in 500 mL of 5% dextrose) at 2-20 μg/kg/min, or
   • Vasopressin 25 units in 250 mL (0.1 U/mL) at 0.01-0.04 U/min 2
9. For patients on beta-blockers: Glucagon 1-5 mg IV over 5 minutes 2
10. Administer corticosteroids:
    • 1-2 mg/kg of IV methylprednisolone every 6 hours 2
11. Monitor vital signs until resolution
12. Observe patient for 24 hours after severe reactions 2

Prevention Strategies

1. Proper injection technique:

   • Rotate injection sites within chosen area (e.g., stomach or upper arm) 3
   • Never inject into a vein or muscle 3
   • Cleanse skin before injection 1

2. Patient education:

   • Training on proper self-injection techniques 1
   • Recognizing early signs of reactions 2

3. Consider premedication for patients with history of reactions 1

Special Considerations

• Insulin injections: Injection site reactions with insulin may present as lipodystrophy or local allergic reactions. Change injection sites regularly to prevent these complications 3

• Biological agents: ISRs are common with biological agents (0.5-40% incidence) but are generally not correlated with drug efficacy or development of antidrug antibodies 4. Most reactions are not true allergic responses and do not warrant discontinuation of therapy 4

• Delayed reactions: Some injection site reactions may occur 1-14 days after administration, particularly with monoclonal antibodies, presenting as myalgia, arthralgia, headache, fever, rash, and fatigue 2

• Polysorbate excipients: Some injection site reactions may be caused by polysorbate excipients in the formulation rather than the active drug itself 5

Documentation

Accurate documentation of injection site reactions should include:

• Pre-injection assessments
• Description and grading of the reaction
• Management approach used
• Patient response to interventions 2

Important Cautions

• Rechallenge after severe reactions (grade 3 or higher) or true anaphylaxis should not be attempted 2
• For patients experiencing persistent or worsening injection site reactions despite appropriate management, consider alternative medications or formulations 6
• Misunderstanding the pathophysiology of injection site reactions may lead to unnecessary discontinuation of effective treatments 4