Evaluation of the Efficacy, Safety, and Tolerability of PL-14 Allergy Blocker Compared to Saline Spray in Patients With Seasonal Allergic Rhinitis

Inclusion Criteria: 1. Clinical history of seasonal AR, as reported by the subject, with symptoms for more than two years and exacerbations during the study season for the relevant seasonal allergen (e.g., tree/grass pollen/ragweed). 2. Positive skin prick test (i.e., wheal ≥3 mm larger than the diluent control with erythema) or positive in vitro tests for specific IgE against allergen(s) relevant to the enrollment period at Baseline or within 12 months before enrollment . 3. Age ≥ 18 years and ≤ 75 years at Screening. 4. Active symptoms of seasonal AR with an rTNSS score ≥5 at randomization (based on the average rTNSS score during the Run-in Period and rounded to the nearest whole number). 5. Willing and able to complete a 7-consecutive-day washout prior to the Baseline/Randomization visit, during which the subject will abstain from: (1) oral or systemic H1 antihistamines, (2) topical antiallergic treatment, (3) nasal vasoconstrictors (Intermittent use of Astepro Allergy - Antihistamine (azelastine) nasal spray as rescue medication is allowed during the trial). 6\. Females must be non-pregnant and non-lactating, and at least one of the following must apply: i) not a woman of childbearing potential (WOCBP) (post-menopausal for ≥ 12 months and confirmed through testing of FSH levels ≥ 40 IU/L at Screening Visit); ii) WOCBP using a contraceptive method that is highly effective (a low user-dependency method OR a user-dependent method in combination with barrier method) (plus: negative urine pregnancy test and Screening Visit, within 24 hours before the first dose of study intervention and willing to have additional pregnancy tests as required throughout the study ; iii) WOCBP abstinent from sexual intercourse as their preferred and usual lifestyle (abstinent on a long-term and persistent basis) for 28 days from the start of study intervention. 7\. Willing and able to attend all trial visits. 8. Able to read and understand study documents and follow instructions from the Investigator and study personnel during visits. 9\. Signed IRB/EC-approved informed consent form obtained prior to any study-related procedures. Exclusion Criteria: * 1\. Presence of active, moderate or severe symptoms of non-allergic rhinitis , acute inflammation of the nose, or paranasal sinusitis at Screening or within the 7 days prior. 2\. Positive rapid-result COVID-19 antigen test. 3. Uncontrolled asthma under treatment with any medication other than inhaled short-acting beta-2 agonists, or with known FEV1 \< 70% within the previous 6 months. 4\. Diagnosis or symptoms of acute respiratory infection at Screening or within the previous 4 weeks. 5\. Vaccinations: i) live vaccine(s) within 1 month prior to Screening or planned during the study; ii) killed vaccine within 1 week prior to Screening; iii) planned COVID-19 vaccine from Day -7 through Day 14. 6\. Nasal or paranasal sinus surgery within the previous 8 weeks. 7. Long-term continuous use of inhaled or intranasal glucocorticosteroids (intermittent use is allowed). 8\. Initiation of allergen immunotherapy within 3 months prior to Screening, or failure to have reached the maintenance phase of allergen immunotherapy at the time of enrollment, or any change in allergen immunotherapy dose or regimen within 1 month prior to Screening. 9\. Treatment with leukotriene receptor antagonists (at Screening or within 1 week prior) or regular/chronic use of nonsteroidal anti-inflammatory drugs (NSAIDs) at screening or within 1 week prior. Intermittent NSAID use as relief/rescue medication is allowed. 10\. Known hypersensitivity to any constituent of the study devices (test \& control) . 11\. Clinically significant nasal abnormalities that may interfere with proper device administration or affect nasal airflow, including but not limited to: * Nasal septal deviation associated with clinically significant nasal obstruction, as determined by the investigator based on physical examination, and resulting in functional impairment (e.g., patient-reported difficulty in airflow). * Nasal polyps * Chronic rhinosinusitis (with or without nasal polyposis) * Turbinate hypertrophy of clinical significance * History of nasal surgery within the past 6 months * Structural abnormalities (e.g., perforated septum, severe nasal valve collapse) * Active nasal infection or acute sinusitis Subjects presenting with any of these conditions will be excluded from participation. 12\. Any clinically relevant autoimmune, respiratory (especially with reduction of respiratory capacity) or cardiovascular disease, malignant tumors, bleeding disorders, autoimmune diseases, neurological disorders, or any other abnormality that, in the opinion of the Investigator, may pose a safety risk, confound the clinical performance or safety assessment, or interfere with study participation. 13\. Concurrent participation in another clinical study or participation in another clinical study within 30 days prior to Screening. 14\. A history of alcohol or drug abuse, within 2 years prior to screening, or current use of recreational drugs (particularly intranasal). 15\. Planned travel to a region outside the designated pollen area for the Clinical Research Unit (CRU), as defined in the informed consent form, for ≥24 hours during the 7-day Run-in Period, OR for ≥2 consecutive days or a total of ≥3 days between the randomization visit and the follow-up phone call