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Drug Allergy
A drug allergy is an immune reaction to a medicine, ranging from a mild rash to a severe, life-threatening reaction. It is important to know which medicines you react to.
Causes & risk factors
- Immune reaction to a medicine
- Common with some antibiotics (like penicillin) and painkillers
- Previous exposure to the same drug
- A history of other allergies
- Certain infections increasing reaction risk
Common symptoms
- Rash or hives
- Itching
- Swelling of the face, lips or tongue
- Fever
- Wheezing or breathing difficulty
Tests & diagnosis
- Detailed history of the reaction
- Skin testing for some drugs
- Specific IgE blood test where available
- Supervised drug challenge in select cases
Treatment & management
- Stopping the medicine responsible
- Antihistamines for mild rashes
- Emergency treatment for severe reactions
- Recording the allergy clearly in your records
- Using an alternative safe medicine in future
When to see a doctor urgently
- Swelling of the throat, breathing difficulty or collapse — call your local emergency number now
- Blistering rash, peeling skin or mouth sores — urgent (serious reaction)
- A widespread rash or fever after starting a medicine
- Any reaction so it can be recorded and avoided
Not a diagnosis. MedDroid gives general educational information about drug allergy. It cannot examine you, diagnose or prescribe — always confirm with a qualified doctor.
Frequently asked questions
Are all drug side effects allergies?
No. Many side effects (like nausea) are not allergies. A true drug allergy involves the immune system and can cause rash, swelling or breathing problems.
Should I tell doctors about a drug reaction?
Always. Tell every doctor and pharmacist, and consider wearing a medical alert, so the medicine is avoided in future.
Explore more
Sources & further reading
- World Health Organization (WHO)
- MedlinePlus — U.S. National Library of Medicine
- Ministry of Health & Family Welfare, India
- Indian Council of Medical Research (ICMR)
Reviewed by Dr. Sanjay Anbu, MBBS. MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.