Asymptomatic drug-induced eosinophilia is a high eosinophil count associated with a drug that does not present with any clinical symptoms. It is generally discovered incidentally upon laboratory examination.

Other eosinophilic disorders (eg, drug-induced hypersensitivity syndrome [DRESS]) are covered separately.

Eosinophilia may result from nearly any prescription or nonprescription medication, dietary supplement, or herbal supplement. In most cases of drug-induced eosinophilia, the condition is asymptomatic and there are no clinical consequences.

The specific prevalence rate of drug-induced eosinophilia is challenging to estimate because patients may be unaware. It may not be detected unless there is associated end organ involvement or it is revealed incidentally during routine CBC with differential monitoring. One prospective study that examined eosinophilia rate with parenteral outpatient antibiotic use found that 25% of the study population developed eosinophilia.

Cephalosporins and penicillins are some of the most implicated drugs in asymptomatic drug-induced eosinophilia.