What is drug allergy?


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Know the basics

What is drug allergy?

Drug allergy is defined as the abnormal reaction of the immune system to a medication. Any medication, including over-the-counter, prescription or herbal can lead to drug allergy.

Drug allergy might affect people differently. The most common symptoms of drug allergy are hives, rash or fever. Serious reactions include anaphylaxis, a life-threatening condition where your body goes into shock, your blood pressure drops suddenly and your airways tighten up. A drug allergy is not the side effects of drug nor a condition caused by overdose.

How common is drug allergy?

Drug allergy can happen to anyone. Unfortunately, there is no way to test if you are allergic to a drug. In most cases, people learn about their drug allergy when they take a drug.  It can affect patients at any age. It can be managed by reducing your risk factors. Please discuss with your doctor for further information.

Know the symptoms

What are the symptoms of drug allergy?

Symptoms of drug allergy commonly occur within an hour after taking a drug. The common symptoms of drug allergy are:

  • Skin rash;
  • Hives;
  • Itching;
  • Fever;
  • Swelling;
  • Shortness of breath;
  • Wheezing;
  • Runny nose;
  • Itchy, watery eyes.

Some drugs might induce severe reaction in people. Some of the more serious symptoms that need medical attention are:

  • Fast heartbeat or pulse;
  • Tightening of the airways and throat, causing trouble breathing;
  • Anxiety or dizziness;
  • Loss of consciousness;
  • Hives and trouble breathing.

However, it is possible that drug allergic reactions occur days or weeks after taking the drug, or the symptoms will continue even if you stop using the drugs. Some long-term conditions from drug allergy are:

  • Fever, joint pain, rash, swelling and nausea;
  • Anemia: a reduction in red blood cells, causing fatigue, irregular heartbeats, shortness of breath and other symptoms;
  • Rash, high white blood cell counts, general swelling, swollen lymph nodes and recurrence of dormant hepatitis infection;
  • Inflammation in the kidneys (nephritis), which can cause fever, blood in the urine, general swelling, confusion and other symptoms.

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

Drug allergy can bring mild symptoms to very serious, life threating ones. You should contact your doctor if you have any of the following:

  • A fast-spreading painful red or blistered area on theskin;
  • Top layer of skin peels off in sheets without blistering;
  • Scalded-looking raw areas of flesh;
  • Discomfort;
  • Fever;
  • Rash or blister spreading toeyes, mouth, and genitals.

Seeking an emergency care in case of a severe reaction: having impact on blood pressure, breathing.

Know the causes

What causes drug allergy?

Drug allergy is caused by a reaction of your immune system to the chemical in the drug. Your immune system mistaken the drugs for harmful chemical and start to attack it. Scientists often link drug allergy back to the  first exposure to a certain drug, such as in food, water, or drugs that you take for a certain condition. If your immune system react badly with the drug in the first exposure, your body will create antibody, leading to drug allergy.

Although any drug can cause an allergic reaction, some drugs are more common than others in causing allergic reaction, including:

  • Antibiotics, such as penicillin;
  • Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs);
  • Chemotherapy drugs for treating cancer;
  • Medications for autoimmune diseases, such as rheumatoid arthritis;
  • Corticosteroid creams or lotions;
  • Medications for people with HIV or AIDS;
  • Bee pollen products;
  • Echinacea – an herb used to treat common cold;
  • Dyes used in imaging tests (radiocontrast media);
  • Opiates for treating pain;
  • Local anesthetics.

Know the risk factors

What increases my risk for drug allergy?

There are many risk factors for drug allergy, such as:

  • A history of other allergies, such as food allergy or fever;
  • History of allergic reaction to another drug with the same active ingredient;
  • Family history of drug allergy;
  • High doses, repetitive use or prolonged use of drug;
  • Infection with HIV or the Epstein-Barr virus.

Understand the diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is drug allergy diagnosed?

Drug allergy can be diagnosed through:

  • Physical examination: Your doctor will examine physical reaction to the drugs such as signs of rash and blister, or listen to your heartbeat and check your airways.
  • Asking questions about history of allergic reactions, history of medication, situation. If you are allergy to another drug with the same ingredient, you might develop an allergy to drugs of the same type.
  • Your doctor might order some lab test to find out which ingredient you are allergic to. Additional tests include:
  • Skin tests;
  • Blood tests.

How is drug allergy treated?

Drug allergy can be treated by reducing allergy symptoms or using another treatment that can help you be able to take allergy-causing drug.

  • Taking antihistaminesto block immune system substances activated during an allergic reaction;
  • Stop using allergy-causing drug;
  •  Treating allergy symptoms include:
  • Taking corticosteroids  to treat inflammation associated with more-serious reactions;
  • Taking an immediate epinephrine injection and have hospital care to maintain blood pressure and support breathing.
  • Treatments that allow you to take allergy-inducing drugs are performed under careful observation of your doctor. These treatments aim to help you desensitize to the medication.
  • Starting by using a small dose and then increase progressively dose every 15 to 30 minutes over several hours or days until no reaction occur.
  • Testing to see at which dosage your allergy start reacting.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage drug allergy?

The following lifestyles and home remedies might help you cope with drug allergy:

  • Avoid your known allergy triggers as much as you can;
  • Carry self-administered epinephrine, if possible;
  • Take prednisone or antihistamines;
  • Alert your doctor to your drug allergies before any prescription;
  • Exercise caution to stinging insects, when they’re nearby;
  • Carefully read the labels of all the foods you buy and eat.

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: May 30, 2016 | Last Modified: January 4, 2017

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