Drug allergy

Overview

A drug allergy occurs when the immune system reacts abnormally to a medication. Whether it’s a nonprescription drug, a prescription medication, or an herbal remedy, any drug can provoke an allergic response. While most drug allergies manifest as mild symptoms like hives or rashes, some cases can lead to severe, life-threatening reactions.

Types of Drug allergy

1. Immediate Hypersensitivity Reactions:
   • These occur within an hour of drug exposure.
   • Symptoms include skin rash, hives, itching, and fever.
   • Anaphylaxis, a severe systemic reaction, is a rare but critical manifestation.
2. Delayed Hypersensitivity Reactions:
   • These may appear hours, days, or weeks after drug intake.
   • Conditions include serum sickness, drug-induced anemia, and drug rash with eosinophilia and systemic symptoms (DRESS).

Causes of Drug allergy

• Immune System Sensitization:
  • The immune system mistakenly identifies a drug as harmful.
  • Antibodies (IgE) specific to the drug develop.
  • Subsequent exposures trigger an allergic response.
• Common Allergens:
  • Antibiotics (e.g., penicillin, sulfonamides)
  • Analgesics (e.g., aspirin, ibuprofen)
  • Anticonvulsants (e.g., carbamazepine, phenytoin)
  • Chemotherapy drugs.

Risk Factors of Drug allergy

• Repeated Exposure:
  • Allergies may not develop until after several exposures.
• Concurrent Illness:
  • Existing health conditions can influence drug reactions.

Symptoms of Drug allergy

Preventions of Drug allergy

• Avoidance:
  • Stay away from known allergens.
  • Inform healthcare providers about drug allergies.
• Education:
  • Educate patients about potential allergens.

Diagnosis of Drug allergy

• History and Physical Examination
• Diagnostic Tests:
  • Prick/puncture test
  • Blood test
  • Oral drug challenge.

Treatment for Drug allergy

• Severity-Based Approach:
  • Stop the offending drug.
  • Supportive therapy for anaphylaxis.
• Medications:
  • Antihistamines (e.g., cetirizine, diphenhydramine)
  • Corticosteroids (e.g., cortisone)
  • Bronchodilators (e.g., ipratropium bromide, albuterol)
  • Epinephrine (for anaphylaxis).

When to seek medical attention ?

• Emergency:
  • Signs of severe reaction or anaphylaxis.
• Milder Symptoms:
  • Seek medical attention promptly.