Early allergy pill may stop sneezing before it starts

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Participants are eligible to be included in the study only if all of the following criteria apply: * Participant is willing to provide written informed consent. * Adult participants (18 to 80 years old) suffering from seasonal allergic rhinitis (SAR) provoked by Ragweed pollen. * Participants having a total nasal symptom score (TNSS)-3 ≥4 (with 3 nasal symptoms) at first pollen challenge at Visit 2. * Having a 2-year history of SAR with Positive skin prick test to Ragweed allergen at screening (with a wheal diameter at least 3 mm larger than that produced by the negative control). Exclusion Criteria: * History of anaphylaxis to Ragweed pollen History of asthma or exacerbations in the past 12 months requiring regular inhaled corticosteroids for greater than 4 weeks per year, any oral corticosteroid usage, any emergency department visit for asthma or any asthma-related hospitalization. Mild asthmatics treated only with pro re nata short-acting β2agonists, less than 2 doses per week can be enrolled. * History of chronic sinusitis, defined as a sinus symptoms lasting greater than 12 weeks that includes 2 or more major factors or 1 major factor and 2 minor factors. Major factors are defined as facial pain or pressure, nasal obstruction or blockage, nasal discharge or purulence or discolored postnasal discharge, purulence in nasal cavity, or impaired or loss of smell. Minor factors are defined as headache, fever, halitosis, fatigue, dental pain, cough, and ear pain, pressure, or fullness. * History of systemic disease affecting the immune system such as autoimmune diseases, immune complex disease, or immunodeficiency, where, in the opinion of the study physician, participation in the trial would pose a risk or significant effect on the immune system. * Presence or history of drug hypersensitivity to fexofenadine and/or its excipients. * Participants unable to stop the following forbidden treatments/nutriments prior to pollen challenge: * Antihistamines: within 3 days for first-generation antihistamines, within 2 days for second-generation antihistamines. * Intranasal or inhaled corticosteroids: 7 days. * Ocular, intranasal, or inhaled sodium cromoglycate: 14 days. * High doses of systemic corticosteroids: 30 days. * Leukotriene antagonists: 30 days. * Intranasal or systemic decongestants: 3 days. * Tricyclic antidepressants: 7 days. * Any citrus fruits (grapefruit, orange, etc.) or their juices, as well as all fruit juices: 5 days. * Aluminum-and-magnesium containing antacids: 7 days. * Omalizumab/dupilumab: within 6 months * Any contraindications to fexofenadine, according to the labeling. * The above information is not intended to contain all considerations relevant to a potential participation in a clinical trial.