Objective To observe the preventive effect of modified Cang’ erzi San（ 苍耳子散） on radiation nasosinusitis in patients with nasopharyngeal carcinoma receiving radiotherapy. Methods Totally 102 patients with nasopharyngeal carcinoma receiving radiotherapy were enrolled. They were randomly assigned into treatment of 52 cases and control group of 50 cases. The control group received conventional nasal irrigation with vitamin B12. The treatment group was given oral modified Cang’erzi San in addition to the therapy of control group. The course of the treatment were 4 weeks. The integrations of clinical symptom

ciliary transport rate and scores of nasal endoscope and paranasal sinus CT before and after treatment were compared. Clinical effect after treatment and the incidence of radiation nasosinusitis within 3 and 6 months after radiotherapy in both groups were observed. Results The effective rates were 98. 08% and 82. 00% in treatment and control group

respectively. The treatment group was more effective than control（ P < 0. 05）. Developments of nasal congestion

nasal mucosal congestion

turbinate enlargement

nasal secretions and hyposmia and headache score after treatment were significantly lower than those before treatment in both groups. The treatment group had an advantage over control（ P < 0. 05）. Ciliary transport rate and scores of nasal endoscope and paranasal sinus after treatment were higher than those before treatment in both groups

and the treatment group was superior than control（ P < 0. 05）. 9 and 11 cases of radiation nasosinusitis occurred in treatment group within 3 and 6 months after radiotherapy

respectively; while 23 and 28 cases occurred in control. The incidence in treatment group was significantly lower than that in control（ P < 0. 01）. Conclusion Combination of modified Cang’ erzi San and nasal irrigation can improve the sinonasal symptom in patients with nasopharyngeal carcinoma receiving radiotherapy

preventing the onset of radiation nasosinusitis.