A drug allergy is not the same as a drug side effect. A side effect is a known possible reaction to a medicine. Side effects to medicines are listed on their drug labels. A drug allergy also is different from drug toxicity. Drug toxicity is caused by an overdose of medicine.
A drug allergy is the reaction of the immune system to a medicine. Any medicine — nonprescription, prescription or herbal — can provoke a drug allergy. However, a drug allergy is more likely with certain medicines.
Symptoms of drug allergy :
Symptoms of a serious drug allergy often occur within an hour after taking a drug. Other reactions, particularly rashes, can occur hours, days or weeks later. Drug allergy symptoms may include -
✓ Skin rash
✓ Hives
✓ Itching
✓ Fever
✓ Swelling
✓ Shortness of breath
✓ Wheezing
✓ Runny nose
✓ Itchy, watery eyes
• Other symptoms resulting from drug allergy -
Less common drug allergy reactions happen days or weeks after exposure to a drug and may persist for some time after you stop taking the drug. These conditions include:
• Serum sickness, which may cause fever, joint pain, rash, swelling and nausea
• Drug-induced anemia, a reduction in red blood cells, which can cause fatigue, irregular heartbeats, shortness of breath and other symptoms
• Drug rash with eosinophilia and systemic symptoms (DRESS), which results in rash, high white blood cell count, general swelling, swollen lymph nodes and recurrence of dormant hepatitis infection
• Inflammation in the kidneys, also called nephritis, which can cause fever, blood in the urine, general swelling, confusion and other symptoms.
Causes of drug allergy -
A drug allergy occurs when your immune system mistakenly identifies a drug as a harmful substance, such as a virus or bacterium. Once your immune system detects a drug as a harmful substance, it develops an antibody specific to that drug. This can happen the first time you take a drug, but sometimes an allergy doesn't develop until there have been repeated exposures.
The next time you take the drug, these specific antibodies flag the drug and direct immune system attacks on the substance. Chemicals released by this activity cause the symptoms associated with an allergic reaction.
Some allergic reactions may result from a somewhat different process. Researchers believe that some drugs can bind directly to a certain type of immune system white blood cell called a T cell. This event causes the release of chemicals that can result in an allergic reaction the first time you take the drug.
You may not be aware of your first exposure to a drug, however. Some evidence suggests that trace amounts of a drug in the food supply, such as an antibiotic, may be sufficient for the immune system to create an antibody to it.
Know about all type of allergies :
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