This paper presents a case of interstitial lung disease (ILD) during anti-tumor therapy in an elderly breast cancer patient, along with the subsequent glucocorticoid treatment course. Based on the patient's symptoms, signs and comprehensive evaluation of laboratory and imaging findings, and review of relevant literature, the ILD was suspected to be associated with abemaciclib. The causal relationship was determined as highly likely, according to the Common Terminology Criteria for Adverse Events, the severity of the ILD was evaluated as grade 2. The abemaciclib were discontinued and glucocorticoids were administered for anti-inflammation, supplemented with rabeprazole for gastric protection. During the treatment, disease recurrence occurred, which was considered related to overly rapid tapering of glucocorticoid dosage, prompting subsequent dose adjustment and slow reduction of glucocorticoids. Follow-up showed that the patient's ILD had improved. Clinical pharmacists assisted physicians in the differential diagnosis of adverse drug reactions and provided pharmaceutical care, participated in adjusting treatment plans, delivered medication education to patients, and ensured the safety and effectiveness of drug therapy.

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