Drug Allergy

Drug Allergy

Drug Allergy is defined as the reaction of the immune system to a certain drug. In an intolerance, on the other hand, the reaction is produced by other alternative mechanisms. The immune system is capable of producing these reactions through different mechanisms, which means that not all allergic reactions are identical.

Thus, the reactions can be summarized as:

Immediate: They are measured by antibodies and generally occur from minutes to even 6 hours. Delayed:They are measured by cells and occur in hours, days, or even weeks.

Paradox with the “alleged” drug allergies

There are many studies showing that up to 90% of patients who claim to be allergic to penicillin can actually tolerate the medication without problem . These numbers have been corroborated in both Spanish and US studies.

It seems easy to find out the consequences for patients of not informing their doctor of the medications to which they are allergic. These consequences are none other than increasing the risk of having an allergic reaction, which can range from mild to severe, including fatal reactions.

What is less intuitive are the consequences of the opposite: maintaining the diagnosis of allergy to a drug for life, without considering the option of conducting a study that confirms or rules out such allergy.

Consequences of being labeled “allergic to penicillin”

According to studies from the USA and Great Britain, patients “labeled” as allergic to penicillin:

· They present longer hospitalizations, with an average of 0.59 days.

· They are treated with drugs that have higher side effects, including very severe diarrhea, for example.

· They are treated with alternative drugs that are more powerful, and that will lose efficacy and future uses, since the bacteria become accustomed to them and create a kind of resistance to treatment.

· Sometimes penicillins are the most effective for specific bacteria, and therefore these patients are treated with drugs that are less effective.

· It supposes an increase in hospital costs.

· There is an increase in the population of antibiotic resistant bacteria that currently causes 25,000 deaths per year in Europe.

· Increased patient mortality.

· Consequences for public health.

Although there are no major studies of the consequences of a patient’s “mislabelling” as being allergic to other families of drugs other than penicillin, it is likely to find similar results in many other antibiotics.

What if I belong to the 10% of patients who are really allergic to medications?

In case of being really allergic to medications, the team of specialists who have carried out the study must provide a clear and written report on the diagnosis. For some antibiotics and patients, they will also need to perform additional tests to provide specific names of antibiotics that they can take as an alternative, within the family of drugs to which the patient is allergic.

At specific times when the patient needs the drug to which he has been shown to be allergic, the specialist can apply a desensitization protocol, which is nothing more than a procedure to create a temporary tolerance to a drug, during the period in that the patient requires that specific treatment.

Should I have an allergy test?

If the diagnosis was made by a doctor other than a specialist in Allergology, it will be necessary to undergo such a study. An incorrect diagnosis increases the chances of failure of future therapies.

Exceptions to this will be when the risk of allergy testing outweighs the benefits of doing it. Any specialist with experience in drug allergy is able to assess this risk / benefit and will not expose the patient, under any circumstances, to procedures that do not increase their duration and quality of life.