Intervention: Acetylcysteine
Trial phase: Phase 3
ATC code: R05CB01 | S01XA08 | V03AB23
SMILES: CC(=O)N[C@@H](CS)C(=O)O
Sex: All
Age groups: Child | Adult | Older Adult
Healthy volunteers: No
Participants at risk: 238
Group description: four tablets test product per day (taken as two tablets dissolved in a glass of water, twice daily)
Eligibility criteria:
Inclusion Criteria:

Male or female subjects aged between 14 and 75 years inclusive on the date of consent

Diagnosis of acute, uncomplicated rhinosinusitis defined at screening visit 1 and at Visit 2 as:

major symptom score (MSS) assessed by the patient ≥8 and ≤12 points for the following: rhinorrhea/ anterior discharge, postnasal drip, nasal congestion, headache, and facial pain/pressure, whereupon the nasal congestion is mandatory and no more than 3 of the 5 symptoms are rated as severe
individual score for facial pain/pressure ≥1 (mild) and ≤2 (moderate)
presence of symptoms ≤3 days prior to screening visit
For adults (≥18 years): Informed consent to participate in the trial provided in written form; For adolescents (≥14 - <18 years): own subject informed consent/ assent to participate in the trial and the informed consent from all parent(s)/ legal guardian(s) provided in written form.

Exclusion Criteria:

History of hypersensitivity or intolerance to the active substance or any of the excipients of the trial medication
Patient with history of hereditary fructose intolerance, galactose intolerance, lactase deficiency or glucose-galactose malabsorption
Chronic rhinosinusitis (symptoms lasting longer than 3 months)
Subjects who have undergone sinus or nasal surgery for chronic rhinosinusitis in the 6 months prior to screening visit
Sinus lavage within 7 days prior to screening visit
Odontogenic rhinosinusitis
Allergic (perennial or seasonal) rhinitis
Bronchial asthma or chronic obstructive pulmonary disease
Nasal polyposis or clinically relevant nasal septum deviation
Concomitant otitis
Intranasal or systemic use of corticosteroids within 30 days prior to screening visit
Intranasal or systemic use of antibiotics within 30 days prior to screening visit
Use of nasal decongestants within 2 days prior to screening visit

Concomitant treatment of common cold-like symptoms within 7 days prior to screening visit with any of the following:

Analgesics
Non-steroidal anti-inflammatory drugs
Antihistamines
Concomitant use of intranasal saline irrigation
Use of immunosuppressive agents within 30 days prior to screening visit
Immunocompromised state
Suspicion for acute bacterial rhinosinusitis (defined as presence of purulence for 3 to 4 days with fever ≥ 38.3°C)
Pregnant or breast-feeding female patient
Female patient of childbearing potential (not surgically sterilized/hysterectomized or postmenopausal for at least 1 year) who is not currently using (documented at screening visit) and not willing to use medically reliable methods of contraception for the entire trial duration such as oral, injectable or implantable contraceptives, intrauterine contraceptive devices (IUD), sexual abstinence or vasectomized partner
Any other condition of the patient (e.g. serious or unstable medical or psychological condition, acute psychosis) that in the opinion of the investigator may compromise evaluation of the trial treatment or may jeopardize patient's safety, compliance or adherence to protocol requirements
Participation in ANY research study involving another investigational medicinal product (IMP) within 30 days prior to screening visit, or simultaneous participation in another clinical study or previous participation in present study
Suspected alcohol/ drug dependence or abuse (including heavy smoking: ≥ 20 cigarettes daily)
Use of snuff tobacco
Legal incapacity and/or other circumstances rendering the patient unable to understand the nature, scope and possible consequences of the trial

Subjects who are known or suspected:

not to comply with the trial directives
not to be reliable or trustworthy
to be a dependent person, e.g. a relative, family member, or member/employee of the investigator's or sponsor's staff
subject is in custody or submitted to an institution due to a judicial order.