The purpose of this study is to evaluate the effectiveness of a spray the basis of pilocarpine on salivary flow of patients with xerostomia, by radiation therapy, and primary Sjögren's Syndrome treated at the Clinics Hospital of Faculty of Medicine of Ribeirão Preto (HCFMRP-USP), and its impact on quality of life.

There will be two groups: Group 1 (G1) - will use a spray with pilocarpine for three months and after a washout period of a month, use a spray without pilocarpine for another three months; Group 2 (G2) - will use a spray without pilocarpine for three months and after a washout period of a month, use a spray with pilocarpine for another three months (in a randomized, controlled, duble blind and crossover study). Participants will be submitted to OHIP-14, Xerostomia Inventory (XI) and salivary flow measurement before the start of therapy - baseline (T0), one (T2), two (T3) and three (T4) months after starting the use of spray, after washout, crossover occurs and the same parameters are measured for the same periods (T0', T2', T3' and T4'), and is measured one hour after the saliva (T1 and T1') baseline.

Inclusion Criteria:

• Age equal or superior to 18 years;
• Both genders;
• Lucid and without diagnosis of any psychiatric disorder;
• Diagnosed with head and neck cancer and treated for a period of up to 5 years with radiotherapy where the major salivary glands (parotid, submandibular and sublingual) were included in the radiation field;
• Primary Sjögren's syndrome with the diagnosis made by the American-European criteria.

Exclusion Criteria:

• Sensitivity to pilocarpine
• Secondary Sjögren's syndrome;
• Type II diabetes mellitus;
• AIDS;
• pregnant or lactating women;
• Glaucoma;
• Uncontrolled asthma;
• Chronic obstructive pulmonary disease;
• Renal diseases;
• Severe cardiovascular diseases;
• Gastrointestinal disorders;
• Hepatic insufficiency.