Hexylresorcinol (HR) lozenges provide symptomatic relief for sore throats. Despite its recognised anaesthetic and antiseptic properties, evidence of HR bactericidal activity in these formulations is limited, being only recently described in planktonic bacteria. We defined antimicrobial/antiviral activity in planktonic and biofilm models and characterised the pharmacokinetics of HR release from lozenges. Antimicrobial activity (purified or released from lozenges) was determined against oropharyngeal pathogens using minimum inhibitory concentration (MIC) and Log₁₀ reduction assays. Antiviral activity was determined by suspension test (EN14476). Antibiofilm effects employed minimum biofilm eradication concentration assays and confocal laser scanning microscopy. HR release from lozenges was studied in vitro and in vivo using HPLC. HR exhibited MICs ≤ 16 µg/mL against 19/25 strains including: Streptococcus, Staphylococcus and Candida spp. Marked bactericidal activity (>3_log10; >99.9% reduction) occurred within 10 minutes. Significant anti-biofilm activity was evident in streptococcal and candidal biofilms (p < 0.05). Log₁₀ reduction in virucidal infectivity of HR in lozenges ranged from 1-log₁₀ to 3.5-log₁₀. In vivo, HR exhibited rapid release (within 1 minute) from lozenges into saliva. Rapid release and antimicrobial activity of HR against oropharyngeal pathogens was evident, occurring at concentrations ≥ 2-fold lower than present in saliva, highlighting the potential application of HR in the treatment of oropharyngeal infections.

Symptoms of respiratory tract infections (RTI) caused by viral or bacterial triggers include sore throat and cough. Plantago lanceolata (ribwort plantain) is used in herbal medicine to treat symptoms of RTI. This study evaluated the pharmacological actions of P. lanceolata extract (PL) and StrepCough Plantain-Dry cough syrup (PLS) in in vitro models of sore throat and cough. Human tonsil epithelial cells (HTEpiC) cells were stimulated with a combination of lipoteichoic acid and peptidoglycan in the presence or absence of PL or PLS. Levels of TNF-α, IL-6, PGE₂, and COX-2 were measured using ELISA, while phospho-p65 protein levels were measured using Lumit^® immunoassay. The effects of PL and PLS on bradykinin-induced inflammation and increased intracellular Ca²⁺ were investigated in bronchial epithelial cells (BEAS-2B), cells over-expressing TRPV1. Results showed that the pre-treatment of HTEpiC cells with PL and PLS resulted in a significant (p < 0.05) reduction in the LTA + PGN-induced increased production of TNFα, IL-6, PGE₂, as well as COX-2 and phospho-p65 protein levels. Bradykinin-induced increased levels of TNFα, IL-6, and PGE₂ in BEAS-2B cells over-expressing TRPV1 were also reduced by PL and PLS, while reducing levels of intracellular Ca²⁺. This study has demonstrated that extract of P. lanceolata and StrepCough Plantain-Dry cough syrup reduce inflammation in human tonsil epithelial cells. The extract and syrup also reduced TRPV1-mediated inflammation and increased intracellular Ca²⁺ in BEAS-2B bronchial epithelial cells. This study has provided pharmacological evidence for the use of P. lanceolata in healthcare interventions to treat symptoms of respiratory tract infection.

Topical non-steroidal anti-inflammatory drugs (NSAIDs) such as flurbiprofen and benzydamine may be used for the symptomatic relief of pharyngitis, triggered by infections. The onset and spectrum of anti-inflammatory activity of both drugs were compared in human tonsil (HTEpiC) and bronchial epithelial (BEAS-2B) cells stimulated with poly I:C against key inflammatory mediators. Cells were stimulated with poly I:C for 24 h and treated with flurbiprofen or benzydamine for 20 s, 2 min and 5 min. Production of prostaglandin E2 (PGE₂), tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 beta (IL-1β), interleukin-8 (IL-8), interleukin-18 (IL-18), monocyte chemotactic protein-3 (MCP-3) and C-X-C motif chemokine ligand 10 (CXCL10), as well as cyclooxygenase-2 (COX-2) protein expression, was evaluated. Flurbiprofen significantly (p < 0.05) reduced PGE₂ production and COX-2 expression in both cell types within 20 s of treatment and maintained these effects at 2 and 5 min. However, benzydamine produced delayed, inconsistent inhibition. Although both drugs reduced poly I:C induced IL-6, IL-1β, IL-8 and IL-18 production, the magnitude and onset were greater with flurbiprofen. Flurbiprofen also reduced MCP-3 and CXCL10 in both cell types, alongside significant inhibition of caspase-1 activity. Benzydamine showed limited or no effect and less inhibition of caspase-1. With rapid suppression of the COX-2/PGE₂ pathway, rapid onset and a broad inhibition spectrum, flurbiprofen more comprehensively modulates inflammatory processes in epithelial respiratory models.

Acute respiratory infections (ARIs) are among the most common infectious diseases worldwide and represent a substantial clinical and socioeconomic burden. Despite their predominantly viral aetiology, inappropriate antibiotic prescribing remains common, highlighting the need for effective non-antibiotic treatment strategies. In this narrative review, we summarize the pharmacological properties and potential clinical relevance of Plantago lanceolata and Sisymbrium officinale in the symptomatic management of uncomplicated upper airway infections. A narrative literature search of PubMed/MEDLINE, Google Scholar, and the herbal monographs and assessment reports of the European Medicines Agency was conducted, focusing on experimental, clinical, and real-world evidence related to symptom relief, anti-inflammatory effects, and cough modulation. Emphasis was placed on recent in vitro studies investigating epithelial inflammatory responses and cough-related signalling pathways. In cell-based experimental models, both extracts reduced key inflammatory mediators, including prostaglandin E₂, tumour necrosis factor-α, and interleukin-6, in human tonsil epithelial cells stimulated with bacterial cell wall components. In addition, both plant extracts attenuated bradykinin-induced intracellular calcium signalling in bronchial epithelial cells, which is consistent with, but does not demonstrate, modulation of cough-related pathways. These in vitro findings provide a biological rationale for their traditional use in relieving sore throat, irritation, and cough, but they are not direct evidence of clinical efficacy, and clinical trials of these two extracts are lacking. Given the central role of symptom burden in driving healthcare utilization and antibiotic-seeking behaviour, effective symptomatic therapies are important. Whether herbal medicinal products with anti-inflammatory and cough-modulating properties improve symptom control and thereby support antimicrobial stewardship remains to be demonstrated. Future research should include randomized controlled trials with validated symptom outcomes and real-world studies evaluating the impact of these extracts on antibiotic prescribing in clinical practice.