The undesirable and harmful effects that occur during any use of drugs are drug reactions, if our immune system perceives and reacts to these drugs as a foreign substance, then it is called drug allergy. Only some of the drug reactions are allergic reactions. Drug allergies can come up with very different findings. Its diagnosis and treatment requires experience.

Drug allergy is defined as the immune system’s perception of a drug as a foreign substance and reacting. Various symptoms occur during the use of medicines for different purposes. Most of them do not occur as a result of the reaction of our immune system and are not an allergic reaction. But all these symptoms are mistakenly called drug allergies. A child must be evaluated by pediatric allergist to assess whether the symptoms that occur are allergic or what type of allergic reaction, if allergic. Because some reactions can be severe and life threatening.

What is the Prevalence of Drug Allergies?

Applications to the hospital for unwanted reactions to medicines in children constitute 0.4-10.3% of all hospital applications. In the hospitalized children, drug reactions develop at the rate of 0.6-16.8%. 40-50% of them are allergic reactions. In a study conducted in our country, drug allergy in children 6-9 years of age was reported at a rate of 2.8%.

What are the Symptoms of Drug Allergy?

Drug allergies may present with a wide range of findings. Some of these may be severe life-threatening reactions. Findings may appear as short as 0.5-1 hour after taking the drug, depending on the type of allergic reaction, while some may be seen days later.

The most common findings may be skin redness, itching, hives (urticaria), skin rashes, shortness of breath, runny nose, sneezing. Although it is rarely seen, the most serious finding is anaphylaxis called allergic shock. In anaphylaxis, findings occur within 0.5-1 hours after taking the drug, such as hives, blood pressure drop, diarrhea, vomiting, shortness of breath and fainting. Vital risk may arise if proper intervention is not carried out on time.

In some cases, the findings appear a few weeks later taking the medication, and this makes more difficult to diagnose. The main reactions of these late reactions are drug fever, drug-induced anemia, liver and kidney pathologies, serum sickness and a disease called Stevens Johnson Syndrome / Toxic Epidermal Necrolysis, which progresses with extensive skin and visceral involvement.

What are the Most Common Drugs That Cause Drug Allergy?

Every drug can cause allergies. But some of them cause more often. In children, the antibiotic group in which the penicillin placed, called beta lactam, is included. The second place is aspirin and non-steroidal pain relievers and antipyretics, then muscle relaxant drugs used before surgery, radiocontrast agents used for examinations and drugs used in cancer treatment.

What Are the Risk Factors for Drug Allergies?

Some factors increase the risk of drug allergies. These factors are divided into two, namely the drug or the person.

Drug factors;

  • Frequent consumption of the drug
  • Structural feature of the drug
  • The way of using the drug: Injecting is riskier than oral administration
  • Frequency of application: Frequent use and long use increases the risk.

Personal factors

  • Age: It is less common among children than adults.
  • Hereditary predisposition: Some hereditary structures increase the risk of allergies to certain drugs
  • Having an allergic disease: Asthma, allergic rhinitis or food allergy in the child both increases the risk of allergy to some drugs and causes the resulting drug allergy to be more severe.
  • Liver and kidney disease in the child
  • Allergic to the same drug or another drug before
  • A disease that weakens the immune system or requires frequent medication (such as AIDS, Cystic fibrosis)
  • Drug allergy in the family

When to see a doctor for drug allergy?

In case of any drug allergy suspicion, it will be very useful to contact a child allergy specialist who has been trained and experienced in this field as soon as possible. Drug allergies occur with very different findings and some of them are very dangerous reactions. For this reason, the patient should be evaluated as soon as possible and the correct diagnosis should be made and treated.

How to Prepare When Going to the Doctor for a Drug Allergy?

  • Making some preparations while going to the doctor for drug allergy will be useful for the examination to be more efficient.
  • Note the symptoms and complaints that occur after drug use. If there are any external skin symptoms, photograph them and show them to your doctor.
  • Bring the medications you take with you or write down their names.
  • Bring with you any previous examinations and x-rays.
  • Take note before coming to remember what you want to learn about drug allergies and your child’s condition
  • If allergy tests are required for diagnosis, stop allergy syrup and pills, cough syrup and cold medicines 1 week before arrival, to prevent interference with the test.

How is Drug Allergy Diagnosed?

In order for the patient to be diagnosed correctly, it will be appropriate to evaluate and perform the necessary examinations by the pediatric allergy specialist.

For a correct diagnosis, a good history must be taken first. The relationship between the reaction and the drug should be evaluated. A decision must be made about the type of reaction. Personal risks should be evaluated.

Afterwards, a detailed examination should be made and any symptoms should be detected. However, if a certain period of time has passed, the child may have returned to normal and may have no evidence.

First, complete blood count, C-reactive protein, sedimentation, lung film, if there are findings, tests evaluating liver and kidney functions may be requested.

Blood Allergy Tests in Drug Allergy Diagnosis

Blood tests can be done for diagnosis in drug allergy. But for very few medications, an allergy diagnosis can be made from the blood. Also, the negative result is not very reliable. It does not make us sure that there are no allergy to the drug. In recent years, a test called basophil activation test has been used in drug allergies. Basophil activation test and drug allergy tests are applied in Istanbul Allergy. The interpretation of this test also requires experience. According to the result of this test, information is obtained as to whether a serious reaction will occur with a probability of 80%. With this method, it is safely possible to understand whether you are allergic to many drugs at the same time.

Skin Allergy Test in Drug Allergy Diagnosis

In drug allergies, the most important tests to find the suspected drug are skin allergy tests. In this test drugs that may be responsible for are dropped in the arm, pressed with a pointed object and sent into the skin, early and late reading is made according to the type of reaction. If a certain size of rash occurs in the dropped place, that drug is considered allergic. If this test is negative, the drugs are reconstituted at a certain concentration and injected into the skin and it is evaluated whether allergies develop. If there is no allergy in this test, it is checked if the drug is taken by mouth or injected and if he/she develops an allergy to the drug. As a result of these tests, it is decided whether there is an allergy or not.

However, it is very important that allergy tests are carried out and evaluated by the child allergy specialists who are experienced in this field in order to avoid any mistakes.

Provocation Tests in Drug Allergy Diagnosis

If there is a suspicion of drug allergy and skin tests are negative, the drug will be given in increasing doses to determine whether there is a reaction. However, due to the possibility of a severe reaction to the drug, it should be performed under observation by a pediatric allergist and in a center with intervention conditions.

How is the treatment for drug allergy?

The first aim in the treatment is to treat the existing findings when the patient is seen. The first thing to do is discontinue the drug used. Then, drug treatments are made according to the severity of the reaction. In mild reactions, syrups or pills containing antihistamine are used. In cases that are more serious and do not improve with antihistamines, medicines containing cortisone can be used for a short time such as 3-5 days.

If anaphylaxis (allergic shock) has developed, adrenaline should be done immediately and after the hospitalization other treatments should be applied.


If the patient is allergic to a drug and must use that drug, desensitization process should be done. In this process, the drug is started given with very small increasing doses in 15- to 30-minute intervals, and the patient becomes insensitive to that drug. However, this is only valid during that treatment. When it is necessary to take a break and use it again, he/she becomes allergic again and the same process must be repeated.

What Should Be Done for Prevention in Drug Allergies?

Medications that should not be used by the family given as a list. The patient should state that he has a drug allergy when he goes to any health institution. He/she should also carry a name card or tag, indicating which drug he/she is allergic to. It will be very useful for healthcare teams to know that the patient is allergic to a drug in case of an emergency intervention.

Adrenaline autoinjector should be given to the family and taught to use in cases where anaphylaxis (allergic shock) develops depending on the drug.

As a result;

  • Drug allergy is defined as the immune system’s perception of a drug as a foreign substance and reacting to it.
  • Drug allergies can occur with many different findings. The most common is skin rash, itching and hives. Although less common, it may present with a serious life-threatening finding such as anaphylaxis (allergic shock).
  • The most common drugs are penicillin group and non-steroid pain relievers and antipyretics.
  • There are both personal and drug-related risk factors for drug allergies. Important risks are the child’s previous allergic diseases, family allergies, and frequent and intravenous use of the drug.
  • Drug allergy is diagnosed through blood and skin tests and provocation tests if they do not work.
  • In treatment, the drug responsible should be discontinued immediately. The resulting allergy symptoms should be treated appropriately.
  • If the responsible drug must be used, desensitization should be done.
  • A list of drugs not to use should be kept.
  • The patient should carry an identification card or imprint that indicates the drug he is allergic to.

Leave A Comment

Continue Reading

For appointment and information.