Efficacy and Safety Study of Desloratadine (MK-4117) in Japanese Participants With Seasonal Allergic Rhinitis (MK-4117-204)

Inclusion Criteria:

• Has at least a 2-year history of seasonal allergic rhinitis with typical symptoms

• Male or female who is unlikely to conceive: a surgically sterilized female, femalewho has reached natural menopause, or is of reproductive potential and agrees toeither remain abstinent or use (or have her partner use) 2 acceptable methods ofbirth control from study start through 14 days after the last dose of study drug.

Exclusion Criteria:

• Has a lower respiratory tract infection or has a nasopharyngolaryngeal infection (acute upper respiratory tract infection, acute pharyngolaryngitis, or acutetonsillitis, etc.) requiring treatment

• Has a coexisting infection or systemic mycosis for which there are no effectiveantibiotics

• Has asthma that is under treatment and/or uncontrolled

• Has nasal septum ulcers, nasal surgery, or nasal trauma which have not healed

• Has vasomotor rhinitis or eosinophilic rhinitis

• Has a history of hypersensitivity to antihistamines or ingredients of study drug

• Has had treatment with corticosteroids (oral, injectable, suppository, depot drugs [injectable]) or immunological drugs within 28 days prior to Visit 2

• Is currently receiving treatment with another investigational drug or has receivedan investigational drug within prior 3 months

• Has started specific desensitization therapy (allergen immunotherapy) or nonspecificallassotherapy (Histaglobin, vaccine therapy, etc.) or who has received suchtherapies within prior 3 months

• Has received coagulation or resection using laser therapy etc. for treatment fornasal symptoms

• Will receive nasal nebulizer therapy and/or thermotherapy during study period

• Has severe hepatic, renal, cardiac, hematological disease, or other seriouscoexisting diseases and whose general condition is poor

• Has a history of malignancy or clinically important hematological disorder, exceptfor adequately treated non-melanomatous skin carcinoma or carcinoma in situ of thecervix

• Has a history of severe drug allergy (e.g. anaphylactoid reaction)

• Is pregnant or lactating or may be pregnant

• Is planning a remote trip for more than 1 day during the Symptom Confirmation Periodor for more than 2 days during the Treatment Period.