This study will be conducted in adult participants with symptoms of common cold assessing if 1146A nasal spray reduces the severity of symptoms of the common cold compared to placebo. The study will also evaluate the safety of 1146A compared to placebo.

This will be a multi-center, randomized, parallel-group, double blind, 2-arm, placebo controlled study to evaluate the efficacy and safety of 1146A in adult participants with symptomatic common cold in an outpatient setting.

Inclusion Criteria:

• Demonstrates understanding of the study procedures, restrictions and willingness to participate as evidenced by voluntary written informed consent and has received a signed and dated copy of the informed consent form.
• Aged between 18 to 75 years inclusive.
• Male or female.
• Good general and mental health with, in the opinion of the Investigator or medically qualified designee no clinically significant and relevant abnormalities in medical history or upon physical and Investigator-led nasal examination.
• Females of childbearing potential who are, in the opinion of the Investigator, practicing a reliable method of contraception. Adequate contraception is defined as abstinence, oral contraceptive, either combined or progestogen alone OR injectable progestogen OR implants of levonorgestrel OR estrogenic vaginal ring OR percutaneous contraceptive patches OR intrauterine device or intrauterine system OR double barrier method (condom or occlusive cap (diaphragm or cervical vault caps) plus spermicidal agent (foam, gel, film, cream, suppository)) OR male partner sterilization prior to the female participant's entry into the study, and this male is the sole partner for that participant.
• Investigator confirmed diagnosis of symptomatic common cold with an onset of less than 48 hours prior to randomization. Symptomatic common cold is defined as TSS > 9 AND a score >1 for at least one of the following symptoms: sore throat, runny nose, or blocked nose.

Exclusion Criteria:

• Women who have a positive urine pregnancy test.
• Women who are breast-feeding.
• During the entire study (Screening - last participant visit):
• A. Participant who have used medications or therapies that could interfere with study evaluations and have not had the proper washout period from these medications or therapies or are anticipated to require any concomitant intranasal medication during that period or at any time throughout the study.
• B. Nasal disease(s) likely to affect deposition of intranasal medication, such as chronic sinusitis, rhinitis medicamentosa, clinically significant polyposis, or clinically significant nasal structural abnormalities.
• C. Nasal surgery or sinus surgery within the previous year.
• D. Any condition that prohibits the participant from actuating nasal spray devices (severe rheumatoid arthritis; deformed hands and fingers; missing fingers).
• E. Clinically relevant abnormal physical findings which, in the opinion of the Investigator or sponsor's medical monitor, would interfere with the objectives of the study or that may preclude compliance with the study procedures.
• F. Uncontrolled cardiovascular, pulmonary, renal, hepatic, gastrointestinal, hematological, endocrine, metabolic, autoimmune, neurological, psychiatric or other diseases at screening that would interfere with the study in the opinion of the Investigator.
• G. Participants with seasonal allergic rhinitis if randomization occurs during their expected allergy season or perennial allergic rhinitis.
• H. Severe COPD, persistent asthma, or recent COPD/asthma exacerbation.
• I. An inability to comprehend and satisfactorily use the measurement instruments as determined by the study sites staff on screening.
• J. Participants with a fever > 38°C (100.4°F).
• K. Frequent uses of analgesics (i.e. have taken an analgesic for pain in headache and pain in muscle/joints for at least 1 dose per week on average over the past 6 months).
• Known or suspected intolerance or hypersensitivity to any of the study medications, excipients or investigational device material or to medications of similar chemical classes, any history of drug hypersensitivity or other significant allergic diathesis that could affect study participation and known or suspected contraindications, including history of allergy or photosensitivity to study medication/s.
• Participation in another clinical study (including cosmetic studies) or receipt of an investigational drug within 30 days of the screening visit or 5 half-lives of enrollment, whichever is longer and previous participation in this study (i.e. participants cannot be re-screened or randomized).

Recent history (within the last 5 years) of alcohol or other substance abuse and positive urine drug screen.

• An employee of the sponsor or the study sites or members of their immediate family and persons directly or indirectly involved in the execution of this protocol, including employees of the contract research organization (CRO) and persons related to them.
• On nasal examination by Investigator, the presence of nasal disease likely to affect deposition of intranasal treatment or any superficial or moderate nasal mucosal erosion, nasal mucosal ulceration, or nasal septum perforation at the screening visit. Participants with difficulty in using the nasal spray applicator, "vulnerable" individual (as defined by the IRB e.g. incarcerated person) and any condition not identified in the protocol that in the opinion of the Investigator would confound the evaluation and interpretation of the study data or may put the participant at risk.