Drug allergy is a problem that is relevant for both physicians and their patients. Physicians are responsible for prescribing a particular drug, and it is not always possible to foresee the development of allergic reactions to a particular drug in a particular person. 

In most cases, patients themselves take OTC drugs and drugs that are actively advertised on television. It is these drugs that pose the greatest danger. Thus, in 90% of people suffering from drug allergies, they are caused by aspirin, sulphanilamide drugs (trimethoprim, septrin, biseptol) or antibiotics (penicillin, cefuroxime). It is difficult to estimate the true incidence of allergic reactions. However, it is known that four out of every ten usually are overcautious when asked about drug allergies or confuse allergic reactions with some other.

Allergic reactions to drugs are divided into two types according to the time of onset.

1. Immediate, occurring immediately after ingestion or administration of the drug. They include anaphylactic shock, urticaria fever, allergic edema. 
2. Delayed, developing several days later. They are manifested by fever, urticaria fever, pain in the joints. 

To date, to diagnose drug allergy, skin or provocation tests are used, which can give false positive or false negative results. The basophil activation test (CAST) with patients' medications is specifically designed to detect drug allergy. The drug intolerance test - CAST (Cellular Antigen Stimulation Test) is also called an in vitro provocation test. The method was patented by Prof. De Weck and Dr. Sainte-Laudy in 1994. CAST has the highest specificity compared to the classical histamine release test. The method has 100% specificity. The use of the CAST test avoids the use of life-threatening provocation tests and carries no risk to the patient. The patient gives blood in the laboratory and brings with him a specific drug to which an allergic reaction is suspected.