Drug allergy is a group of immunological reactions characterized by an allergic reaction to a particular drug. The most common allergic drug reactions involve skin pruritus and urticaria or exanthema (skin rash), as well as angioedema lesions (swelling). In more severe cases, anaphylaxis or anaphylactic shock or severe cutaneous drug reactions such as Stevens-Johnson syndrome (acute inflammatory disease) or toxic epidermal necrolysis (blistering and exfoliative skin lesions) may occur.
Which drugs cause allergy?
The drugs that most frequently cause allergic reactions are non-steroidal anti-inflammatory drugs and beta-lactam antibiotics (penicillins and derivatives), although any drug can cause allergic reactions, including diagnostic agents (iodinated contrasts).
How is drug allergy diagnosed?
The most important thing is the clinical history of the allergy episode, where the patient should know the drug involved, latency time of the reaction, treatment used to alleviate the reaction, type of reaction suffered, etc. The next thing to do is to sign the informed consent document, where the risks of drug testing are explained.
From there, depending on the type of reaction and the drug involved, prick tests, intradermal reaction tests, epicutaneous drug tests and, if necessary, drug provocation tests can be performed.
What to do if a drug causes allergy?
Drug allergy is very important at the health care level, since it can limit the treatments that a patient can receive, so you should opt for second-line drugs, usually less effective, more expensive and with more side effects than if it were a first choice. That is why it is recommended that, if a drug allergy is suspected, it should be studied by a team of doctors specializing in Allergology with experience in drug allergy.
If a drug allergy is diagnosed or suspected, always carry the name of the active ingredient responsible for the allergic reaction. If the reaction has been studied, a recommendation sheet should also be carried with the name of the drug family causing the allergy. Thus, if a doctor has to prescribe a pharmacological treatment, he or she must first show you the sheet so that it does not include any drug of the family that produces allergy.
However, there are some cases in which the only option is to take the drug to which one is allergic. These situations occur with some frequency in chemotherapy treatments. To solve this, a desensitization to the drug must be carried out, which consists of administering it very slowly and progressively, always in the presence of an allergist to monitor and treat any reactions that may occur.