What causes a drug allergy?
Almost any medication can trigger an allergic reaction, although commonly implicated drugs include:
- Antibiotics, especially penicillins and sulfonamides
- Anti-inflammatory painkillers (NSAIDs)
- Antiepileptic medications
- Allopurinol
- Certain chemotherapy drugs
- Contrast agents used during imaging
A reaction may occur after the first exposure or after repeated use of the medication.
Symptoms of drug allergy
Symptoms can range from mild to severe and include:
- Itchy skin rash
- Hives (urticaria)
- Facial swelling
- Swelling of the lips or tongue
- Fever
- Blisters or peeling of the skin
- Mouth ulcers
- Difficulty breathing
- Dizziness or fainting
Severe reactions such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), DRESS syndrome, and anaphylaxis are medical emergencies.
How is a drug allergy diagnosed?
Diagnosis is based on:
- A detailed medication history
- Timing of symptom onset
- Physical examination
- Blood tests in selected cases
- Skin biopsy when severe skin reactions are suspected
Never restart a medication that is suspected to have caused a severe allergic reaction without medical advice.
Treatment
Management includes:
- Immediate discontinuation of the suspected drug
- Antihistamines for mild reactions
- Corticosteroids when indicated
- Emergency treatment for anaphylaxis
- Hospital admission for severe blistering disorders
Patients should maintain a written record of confirmed drug allergies and inform all healthcare providers before receiving new medications.
Frequently Asked Questions
Can a drug allergy develop even if I have taken the medicine before?
Yes. Allergies can develop after previous uneventful exposure.
Will every skin rash caused by medicines be an allergy?
No. Some drug eruptions are non-allergic side effects. A dermatologist can differentiate between them.
Should I stop all medicines if I develop a rash?
Do not stop essential medications without consulting your doctor, unless you develop severe symptoms such as breathing difficulty or blistering, in which case seek emergency care immediately.
When should you seek urgent medical care?
Seek immediate medical attention if a rash is accompanied by fever, blisters, skin peeling, facial swelling, breathing difficulty, or involvement of the eyes or mouth.
At DermcareMD Skin and Hair Clinic by Dr Neha Athalye, we offer expert diagnosis and management of drug allergies and severe cutaneous adverse drug reactions using evidence-based care.
