Drug allergy: what it is, symptoms, causes and what to do

Drug allergy is a situation in which the immune system reacts to a medication as if it were a foreign substance, so that it starts to produce antibodies in an attempt to combat and eliminate this harmful substance from the body, resulting in the appearance of symptoms.

Drug allergy is also known as Drug Hypersensitivity Reaction (RHM) and symptoms may appear a few minutes after administration of the drug, whether topical, oral or intravenous, with itching, red and watery eyes, swelling of the face and/or throat, dizziness and a feeling of fainting, for example.

It is important that in the presence of signs and symptoms indicative of drug allergy, the person is referred to the hospital so that the necessary measures can be taken, as in some cases the immune system reaction can be very intense, potentially putting the person’s life in jeopardy. risk.

Drug allergy symptoms

Symptoms of drug allergy may appear a few minutes after administering the medication by inhalation or intravenously, or take about 1 hour to appear in the case of medications administered orally.

The severity of symptoms varies depending on the sensitivity of the immune system. You milder drug allergy symptoms they are:

• Itching and redness in a region of the skin or throughout the body;
• Fever above 38ºC;
• Sensation of a runny nose;
• Red, watery and swollen eyes;
• Difficulty opening your eyes.

On the other hand, some people may be more sensitive to certain medications, resulting in a more intense response from the immune system, which can lead to anaphylaxis, which is a serious allergic reaction that can put a person’s life at risk. You more serious drug allergy symptoms they are:

• Swelling of the tongue or throat;
• Difficulty breathing;
• Dizziness;
• Feeling of fainting;
• Mental confusion;
• Nausea;
• Diarrhea;
• Increased heart rate.

In the presence of signs and symptoms of a severe allergic reaction, it is essential that the person goes to the hospital so that measures can be adopted to help reduce the immune system’s response and alleviate symptoms, promoting quality of life.

How to confirm drug allergy

Drug allergy can be identified based on the evaluation, by the general practitioner or allergist, of the person’s clinical history, the medications used and the symptoms presented.

An allergy test can also be carried out, also called a provocation test, which consists of applying a drop of some medicines to the skin to see whether or not there has been a reaction to different medicines. If no reaction is noticed at the site after a few days, it is considered that the person is not allergic to that medicine. On the other hand, if any symptoms are noticed, the person is considered to have an allergy and should avoid using that medication.

This test, in addition to indicating whether or not the person is allergic to a medication, is also useful for identifying other medications that can be used to replace the one that causes allergies. See how the allergy test is done.

In some cases, when the person reports the occurrence of more serious symptoms, carrying out an allergy test may not be indicated, as it could trigger a more intense immune response. In this case, the diagnosis is usually made only taking into account the person’s health history and medication use.

Main causes

The main medications that cause drug allergies are:

• Antibioticssuch as Erythromycin, Tetracycline, Penicillin and derivatives, such as Amoxicillin and Ampicillin;
• Anticonvulsantssuch as Carbamazepine, Lamotrigine or Phenytoin;
• Insulin of animal origin;
• Iodine contrast for x-ray examinations;
• Aspirin and anti-inflammatories non-steroids, such as Ibuprofen or Naproxen;
• Analgesics, such as dipyrone, mainly;
• Chemotherapeutics;
• HIV medicinessuch as Nevirapine or Abacavir;
• Muscle relaxantssuch as Atracurium, Suxamethonium or Vecuronium

It is important that the medication responsible for the allergy is identified, as this way it is possible to avoid its use and, consequently, the development of symptoms.

What to do

It is important to follow the doctor’s instructions, which may vary depending on the severity of the symptoms. If there has been a mild or moderate allergic reaction, the person may be advised to take an antihistamine, such as hydroxyzine tablets, as long as they are not allergic to this medication.

Additionally, if your eyes are red and swollen, you can place an ice-cold saline compress on the area, which helps reduce swelling and discomfort. If there are no signs of improvement within 1 hour or if more serious symptoms appear in the meantime, you should go to the emergency room.

In the case of more serious symptoms, an ambulance should be called or the person should be taken immediately to the hospital, as there may be difficulty breathing due to the swelling of the throat and tongue, which could put the person’s life at risk. Still in the ambulance, first aid can be started with the administration of antihistamines, corticosteroids or bronchodilator medicines, to facilitate breathing.

In the case of an anaphylactic reaction, it may be necessary to administer an injection of adrenaline and the patient must remain hospitalized for a few hours so that their vital signs are constantly assessed, avoiding complications. It is generally not necessary to stay in the hospital and the patient is discharged as soon as the symptoms disappear. See what first aid is for anaphylactic shock.

Is it possible to avoid allergies?

The only way to avoid an allergy to a certain medicine is to not use that medicine. Therefore, if a person has previously developed allergy symptoms after using a certain medication or knows that they are allergic, it is important to notify doctors, nurses and dentists before starting any type of treatment, in order to avoid complications.