Drug allergy

Drug allergy it is a response of the body to a drug. It is an unexpected, unpredictable immune system reaction that is not related to the effects of the drug itself.

When you take a medicine they can occur Adverse reactions that depend on the dose and the possible interaction with other drugs.

However, there are other types of drug reactions that are unpredictable and have nothing to do with dose or possible drug interactions. Within this group Reactions caused by allergy to medications are included.

Types of allergic reactions to medications

It is impossible to know when an allergic reaction will happen.

Depending on where the reaction occurs, symptoms may vary from the appearance of hives and intense itching, a generalized rash and swelling, to episodes of bronchospam and even anaphylaxis.

Allergic reactions to medications They are divided into two groups, depending on how quickly it appears:

  • Immediate reactions: appear within the first hour of taking the medicine. It is triggered by the production of the antibody or immunoglobulin E (IgE). This is the most commonly diagnosed type of reaction, and it is serious in nature.
  • Late reactionsThey appear within an hour of taking the medicine, although they can often take weeks to develop. This type of drug allergy is triggered by different immune mechanisms, and can lead to various types of reaction.

How often and at what age does a drug allergy appear?

Allergic drug reactions can appear at any age. However, they usually appear around the age of 40.

At this age, it is more normal to need to take more medicine than younger people. Therefore, the possibility of sensitization increases with repeated taking of the drugs.

The frequency of this type of allergic reaction is difficult to determine, since there are no studies on its real incidence. However, it is estimated that they are around 10% of all adverse drug reactions.

About, 5% of adults may be allergic to one or more medications. But it is estimated that 15-25% of the general population may have some kind of reaction with the medication they are using.

Read also: Drug allergy: diagnosis and symptoms

In severe cases, there may be shortness of breath.

How can a drug allergy be diagnosed?

Allergic reactions that most frequently produced are those produced by beta-lactam antibiotics and by non-steroidal anti-inflammatory drugs (NSAIDs).

Diagnosis is based on a detailed history of the reaction and allergy-causing medications. To confirm this, laboratory tests and tests are done on the person, such as skin tests or controlled exposure tests.

Skin tests

They are the most common and they can be intracutaneous, with immediate reading of the result at 15 minutes, or epicutaneous or patch reading at 48 and 96 hours.

The type of test is chosen based on the type and severity of the allergic reaction. The condition of the patient and the need for the drug in question are also taken into account.

Skin tests consist of introducing small amounts of the drug into the skin in different ways being studied.

To perform them, Drug concentrations that have been shown to be non-irritating should be used. Otherwise, they could lead to false positives.

When performing the tests, the patient may experience the allergic reaction that he suffered when taking the drug. For this reason, all the procedure must be well controlled and supervised by experienced personnel.

Also read: How to differentiate an allergy from a cold?

Controlled exposure tests

In certain cases, they may be necessary controlled drug exposure tests, they are done when the rest of the previous tests have been negative and a confirmation is necessary.

To carry them out, increasing amounts of the medicine are given by mouth from time to time, until reaching the therapeutic dose.

A common reaction

Drug allergy cannot be prevented except in the case that you have been diagnosed. In that case, your doctor will rule out the use of that drug and those of the same family.

However, remember the importance of take medications only when needed and as directed given by your doctor or pharmacist.