3 Key questions about drug allergies

Drug allergy is a set of immune-type reactions characterized by an allergic reaction when taking a specific medication. Allergic reactions to most common medications occur with skin pruritus and urticaria or rashes (rash), as well as angioedema lesions (swelling). In more severe cases, they can give anaphylaxis or anaphylactic shock or serious cutaneous drug reactions, such as Stevens-Johnson syndrome (acute inflammatory disease) or toxic epidermal necrolysis (appearance of blisters and exfoliative lesions of the skin).

What medications cause allergy?

The drugs that most often give allergic reactions are non-steroidal anti-inflammatory drugs and beta-lactam antibiotics (penicillins and derivatives), although any medication can give it, including diagnostic means (iodinated contrast agents).

How is medication allergy diagnosed?

The most important is the clinical history of the allergy episode, where the patient must know the medication involved, reaction latency time, treatment used to alleviate the reaction, type of reaction suffered, etc.. The next thing to do is sign the informed consent document, where the risks of drug testing are explained.

From there and depending on the type of reaction and the medication involved, tests may be done in prick, intradermal reaction, patch tests with medication, and if necessary, provocative tests with medication.

What to do if a medicine causes an allergy?

The allergy to medicines is very important at the health level, since it can limit the treatments that a patient can receive, so it is necessary to opt for second-line drugs, usually less effective, more expensive and with more side effects than if it were from one of first choice. That is why it is recommended that, in case of suspecting an allergy to medication, it should be studied by a team of doctors specialized in Allergology with experience in allergy to medicines.

If a drug allergy is diagnosed or suspected, it is necessary to always carry the name of the active ingredient responsible for the allergic reaction. If the reaction has been studied, you should also bring a recommendation sheet that shows the family of the medicine that produces the allergy. In this way, if a doctor must prescribe a pharmacological treatment, first you have to show the sheet so that it does not include any medication of the family that produces allergy.

However, there are some cases in which the only option is to take the medicine to which one is allergic. These situations occur with certain frequency in treatments with chemotherapy. To solve this, a drug desensitization guideline must be implemented, which consists of administering it very slowly and progressively, always with the presence of an allergist to monitor and treat the reactions that may occur.