Diphenhydramine + Dextromethorphan + Levomenthol

• Symptomatic relief of cough associated with upper respiratory tract infections
• Management of allergic conditions accompanied by cough, such as allergic rhinitis or postnasal drip
• Temporary relief of throat irritation and minor nasal congestion
• Suppression of non-productive (dry) cough
• Adjunct treatment in cold and flu symptoms

• Route: Oral
• Adults and Adolescents (≥12 years):
• Syrup or solution: 10 mL every 4 to 6 hours as needed; do not exceed 60 mL in 24 hours
• Lozenges: 1 lozenge every 2 to 4 hours; maximum 6 lozenges per day
• Children (6–11 years):
• Syrup: 5 mL every 4 to 6 hours; maximum 30 mL per 24 hours
• Use under medical supervision
• Children under 6 years:
• Use not recommended due to risk of serious side effects
• Elderly:
• Use with caution due to increased risk of sedation and anticholinergic effects
• Special Populations:
• No specific dose adjustments; caution in hepatic or renal impairment
• Administration Notes:
• Shake syrup or solution well before use
• Avoid use with other CNS depressants or anticholinergic drugs

• Diphenhydramine: A first-generation antihistamine that blocks H1 histamine receptors, reducing allergic symptoms and exerting anticholinergic effects that decrease mucus secretion and cause sedation.
• Dextromethorphan: Acts centrally on the cough center in the medulla by antagonizing NMDA receptors and sigma-1 receptors, suppressing the cough reflex without depressing respiratory function.
• Levomenthol: A topical analgesic and mild local anesthetic that stimulates cold receptors in the throat and nasal mucosa, providing a soothing effect and mild decongestion.

Together, these components provide symptomatic relief of cough, throat irritation, and allergic nasal symptoms.

• Diphenhydramine:
• Absorption: Rapidly absorbed orally with peak plasma concentrations in 2–4 hours
• Metabolism: Extensively metabolized in the liver via CYP2D6
• Half-life: 4–8 hours
• Excretion: Mainly renal as metabolites
• Dextromethorphan:
• Absorption: Rapid oral absorption, peak plasma levels in ~2 hours
• Metabolism: Hepatic metabolism primarily via CYP2D6 to active metabolite dextrorphan
• Half-life: 3–6 hours (varies with CYP2D6 genotype)
• Excretion: Renal elimination of metabolites
• Levomenthol:
• Minimal systemic absorption due to topical/local action
• Metabolized hepatically and excreted renally

• Pregnancy:
• Category B (Diphenhydramine and Levomenthol); C (Dextromethorphan)
• Use only if clearly needed; benefits should outweigh potential risks
• Lactation:
• Diphenhydramine and dextromethorphan are excreted in breast milk; potential sedation in infants
• Caution advised; monitor breastfed infants for sedation or irritability

• Primary Classes:
• Diphenhydramine: First-generation H1 antihistamine
• Dextromethorphan: Antitussive (cough suppressant)
• Levomenthol: Topical analgesic and decongestant

• Known hypersensitivity to any component
• Concurrent use of MAO inhibitors or within 14 days of MAO inhibitor therapy
• Severe hepatic or renal impairment (relative contraindication)
• Children under 2 years (risk of respiratory depression)

• Use cautiously in patients with glaucoma, asthma, COPD, urinary retention, or prostatic hypertrophy due to anticholinergic effects of diphenhydramine
• Risk of CNS depression and sedation; avoid operating machinery or driving
• Potential for misuse/abuse of dextromethorphan at high doses
• Avoid concurrent use with other CNS depressants or alcohol
• Monitor elderly patients closely due to increased sensitivity to anticholinergic and sedative effects

• Common:
• Sedation, dizziness, dry mouth (diphenhydramine)
• Nausea, vomiting (dextromethorphan)
• Mild throat irritation or local burning (levomenthol)
• Serious/Rare:
• Confusion, hallucinations, especially in overdose or elderly
• Respiratory depression (rare)
• Allergic reactions including rash, urticaria

• CNS depressants (e.g., benzodiazepines, opioids) — increased sedation and respiratory depression risk
• MAO inhibitors — hypertensive crisis or serotonin syndrome risk with dextromethorphan
• Other anticholinergic drugs — additive anticholinergic effects
• Alcohol — enhanced CNS depression

• No major recent changes in indications or dosing
• Increased warnings about potential misuse/abuse of dextromethorphan-containing products
• Emphasis on cautious use in pediatric and elderly populations

• Store at 20°C to 25°C (68°F to 77°F)
• Protect from light and moisture
• Keep tightly closed and out of reach of children
• Do not freeze