Drug allergy – diagnosis and symptoms!

Drug allergy is an abnormal reaction of the immune system to that medication. It is important to know that no medication is allergy free. This means that all medications, whether over-the-counter, doctor-prescribed or herbal, can cause allergies. However, some drugs produce allergies with a higher incidence than others.

In order for the symptoms that occur to be considered an allergy, they have to appear through immunological mechanisms. If they are produced by other mechanisms, they should not be called an allergy, although the final symptoms are the same. Both allergies and other types are part of what are called adverse drug reactions.

Symptoms of drug allergy:

Once the drug that will develop the allergy in the patient is taken, the characteristic symptoms of the reaction usually appear at the time. However, there are other symptoms, especially cutaneous ones, that can appear late, even weeks later.

Some characteristic symptoms of drug allergy are:

  • Rash: Also considered redness, skin inflammation, skin lesion, flushing, salpullo, or erythema. These conditions involve changes in skin color or texture;
  • Urticaria: is a skin disease characterized by swollen skin lesions. It is usually accompanied by itching or burning;
  • fever ;
  • Swelling and itching ;
  • Shortness of breath and whistling when breathing;
  • Watery and itchy eyes .

It is possible that in some cases an anaphylactic reaction can be triggered by drug allergy . If this occurs, the patient’s life could be in danger as it causes widespread dysfunction of the body’s systems.

When an anaphylactic reaction is triggered, the airways narrow, which causes difficulty breathing. Nausea and cramps also appear, as well as vomiting and diarrhea. On the other hand, patients who are under these conditions may experience seizures, loss of consciousness, a weak and rapid pulse, and drops in blood pressure.

Other signs and symptoms:

As mentioned above, there are some allergy symptoms that are triggered over a long period of time after taking the medication. Also, some of them may persist as well. Examples of these reactions can be:

  • Serum sickness: This illness can occur with fever, joint pain, rash, swelling and nausea ;
  • Anemia: characterized by having lower than normal red blood cell counts. This situation results in fatigue , irregular heartbeat, shortness of breath , etc.;
  • Eosinophilia and systemic symptoms: which causes rash , elevation of white blood cells, generalized swelling, inflammation of lymph nodes, and recurrence of latent hepatitis infection;
  • Nephritis: Inflammation of the kidneys can cause fever , blood in the urine, confusion, and other symptoms.

How is medication allergy diagnosed?

To avoid anaphylactic reactions or other unpleasant situations for patients, it is essential to have an accurate diagnosis. Some research has shown that drug allergy can be overdiagnosed and that patients who claim to have it never confirm it.

If a proper diagnosis is not made, it can happen that patients use less appropriate antibiotics and more expensive drugs. Therefore, the doctor should perform a physical exam and ask some questions.

The patient should collaborate with the physician in providing details about the onset of symptoms, duration of treatment, and improvement or worsening of symptoms. The tests that medical personnel must perform are:

Skin tests: A small amount of the suspected drug is given to the skin with a needle that scrapes the skin, with an injection, or with a patch. If the medication produces an allergy, a red bump will appear.

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Blood tests: This technique is done to rule out other conditions that can cause the symptoms. However, they are not used often due to limited research on their accuracy.

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