Effects of Phenylephrine on Nasal Congestion in Participants With Seasonal Allergic Rhinitis (P08156 AM2)(Completed)

Inclusion criteria: * Female participants of reproductive potential must have a negative pregnancy test and agree to use acceptable methods of birth control throughout the study. * Participant is willing to stop use of current decongestant and allergy medications during the trial. * Participant has a documented or self-reported history of seasonal allergy. * Participant has documented positive skin testing to spring pollen allergens. * Participant has nasal congestion of at least moderate severity. * Participant has mean seated (after 5 minutes of rest) systolic/diastolic blood pressure ≤138/88 mmHg. * Participant has clinically acceptable physical exam and 12-lead electrocardiogram (ECG). * Participant is without clinically significant disease. * Participant must agree not to take monoamine oxidase inhibitor (MAOI) from 14 days before trial participation until 14 days after the end of the trial. * Participant must sign an informed consent form Exclusion criteria: * Participants must not have any significant medical condition that is a contraindication to the use of phenylephrine HCl or loratadine, such as thyroid disease, uncontrolled diabetes mellitus, coronary heart disease, ischemic heart disease, elevated intraocular pressure, or prostatic hypertrophy. * Participants with a history or presence of hypertension. * Participants who have started allergen immunotherapy within a month preceding enrollment or starting allergen immunotherapy or anticipating immunotherapy dose change during the trial. Xolair (omalizumab) may not be used within 4 years prior to trial participation. * Participants who have a known allergy or intolerance to phenylephrine HCl, any other decongestant, loratadine, desloratadine, or any other antihistamine. * Participants with persistent asthma, rhinitis medicamentosa, or acute or chronic sinusitis, or a history of significant sinusitis within one month of enrollment. * Participant with a history of intermittent asthma may be considered for enrollment provided they have no asthma symptoms at the time of enrollment and use only a short acting beta2-agonist less than twice weekly. * Participants who have used systemic (oral, rectal, injectable), topical, or nasal corticosteroids in the last 30 days (up to 1% topical hydrocortisone is permitted). * Participants using a leukotriene receptor antagonist for maintenance treatment of asthma. * Participant with a history of any illness that, in the opinion of the study investigator, might confound the results of the study or poses an additional risk to the participant by their participation in the study. * Participant with a history of immunological disease or malignancy within the past 5 years, with the exception of non-melanoma skin cancer. * Participant with positive drug screen (participants on prescribed medication resulting in a positive drug screen result may still be enrolled at the discretion of the investigator). * Participant has had major surgery or participated in another investigational study within 4 weeks prior to the Screening Visit. * Participants taking any herbal supplements during trial conduct.