Dacomitinib, as a second-generation EGFR-TKI, has common side effects mainly concentrated in the skin and mucosal system. Symptoms can be effectively controlled through graded management and preventive measures. The following provides a systematic explanation from the mechanism of occurrence to clinical management.

1. Paronychia (nail periarthritis)

(1) Incidence: About 30% of patients experience grade 1-2 symptoms, which are most common after 2-8 weeks of treatment.

(2) Preventive measures: Keep hands and feet dry and avoid external injuries; Use urea ointment to soften keratin.

(3) Grading treatment: Grade 1 local antibiotic ointment; Grade 2 requires topical use in combination with glucocorticoids; Suspend medication for levels 3 and above.

2. Oral inflammation

(1) Clinical manifestations: erythema and erosion of oral mucosa, often accompanied by pain.

(2) Daily care: Use a soft bristled toothbrush and mouthwash containing benzocaine to alleviate symptoms.

(3) Drug treatment: Dexamethasone mouthwash is recommended for grade 2 symptoms; Grade 3 requires dosage adjustment.

3. Dry skin

(1) Pathological mechanism: EGFR inhibition leads to abnormal differentiation of keratinocytes.

(2) Moisturizing strategy: Use non-alcoholic moisturizer daily and keep the bath water temperature below 40 ℃.

(3) Complications management: Prophylactic use of antibiotic ointment is necessary when cracks appear.

4. Other skin toxicities

(1) Acne like rash: incidence>50%, mostly distributed on the head and face.

(2) Treatment principle: Use 1% hydrocortisone cream for Grade 1; Add doxycycline at level 2.

(3) Photoprotection: Strict sun protection (SPF ≥ 30) is required during treatment.

5. Systematic management

(1) Baseline assessment: Check skin condition and oral health before treatment.

(2) Follow up monitoring: Skin toxicity grading assessment will be conducted every 2 weeks.

(3) Multidisciplinary collaboration: In severe cases, dermatological consultation is required.