An unwanted side effect of drugs is called as drug allergy reaction. Allergic reaction caused by drugs varies from mild to severe. Early recognition of drug allergy is essential to avoid life threatening conditions.
Signs and symptoms of drug allergy
Symptoms of drug allergy are different from the symptoms of the disease. Symptoms of drug allergy occur due to the effects of the drug on the body and occur within a few days after the start of the medication. Some of the common symptoms associated with drug allergic reaction are:
1) Redness, itching and swelling on the skin and face.
2) Vertigo and dizziness.
3) Difficulty in breathing, rapid, fluttering, weak pulse.
4) Nausea, vomiting and diarrhea.
5) Cramps in the abdomen.
Causes of drug allergy
Drug allergic reaction is the hypersentivity reaction of our immune system. Drugs produce antigens against which our body’s immune system produces antibodies. Antibodies produced to fight against an allergic reaction are Immunoglobin E (IgE). Drug allergic reaction is produced if large doses of drugs are taken over a longer period of time.
Drug allergic reaction can also occur due to interaction between two or more drugs. It is not necessary that signs and symptoms of drug allergic reaction are produced during first time ingestion of the medication. Most drug allergic reactions are produced by repetitive ingestion of the same medication.
Our body produces chemicals to fight against the large doses of drugs such as histamines.
Common drugs that initiate an allergic reaction include antibiotics such as penicillin, painkillers (morphine), and non-steroidal inflammatory drugs (such as aspirin).
Diagnosis of drug allergy
It is not an easy job to diagnose drug allergic reaction, as sometimes an allergic reaction to a drug occurs in a few days, but sometimes may not occur immediately.
Laboratory test helps in the diagnosis of a drug allergic reaction. Antibodies are detected in the blood which is specific to a particular drug.
To diagnose an allergic reaction to a drug it is very important for a doctor to review about the medical history of a patient. A doctor should ask about the current medication if any taken by the patient, past medical history and any other allergies.
Skin tests are also valuable in diagnosis of certain drug allergic reactions but it has a limited scope.
Diagnostic tests may prove helpful in future treatment of the disease.
Prevention of drug allergic reaction
- The best way to prevent drug allergic reaction is to stop the medication and to avoid its use in future.
- Antidotes are available for specific drug allergic reaction.
- People with severe allergic reaction should wear a medical bracelet to alert the health care professionals and other people.
References
Adkinson NF Jr. Drug Allergy. In Adkinson NF Jr., Yunginger JW, Busse WW, Bochner BS, Holgate ST, eds. Middleton's Allergy: Principles and Practice. 6th ed. Philadelphia, Pa; Mosby Elsevier; 2003: chap 92.
Grammer LC. Drug Allergy. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 275.
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