Dextromethorphan / Promethazine

Temporary relief of cough and upper-respiratory symptoms associated with allergy or the common cold. Not treatment of lower-respiratory symptoms, including asthma; do not infer disease-modifying infection treatment, chronic-cough control, pediatric vomiting treatment or psychiatric use. Promethazine’s antiemetic properties do not establish an antiemetic indication for this fixed cough combination.

Use a calibrated oral syringe/cup for the prescribed mL dose; household teaspoons are unreliable for small doses. Take only the prescribed amount and avoid duplicate promethazine, dextromethorphan or other sedating cough/cold medicines. Older adults generally start low and need close sedation assessment. The selected label supplies no validated renal/hepatic dose table or universal duration; hepatic impairment requires caution, while renal disease needs individual review. No pediatric mg/kg rescue formula, other concentration conversion or double missed dose recommended.

Below 2 years of age; receiving an MAO inhibitor; comatose states; known hypersensitivity or idiosyncratic reaction to promethazine/other phenothiazines. Antihistamines are contraindicated for treatment of lower-respiratory-tract symptoms including asthma. The label supplies no safe infant dose or permission to treat asthma cough with this product.

Promethazine should not be used below 2 years because postmarketing respiratory depression, including deaths, occurred across many weight-based doses. At age ≥2 use the lowest effective prescribed dose cautiously and avoid concomitant respiratory-depressant drugs.

Drowsiness is prominent; dizziness, confusion, blurred vision, dry mouth, GI upset, photosensitivity and BP/heart-rate changes can occur. Serious reports include seizures, EPS, blood dyscrasias, jaundice, airway allergy, apnea and NMS. Overdose may produce excitation/psychosis or profound CNS depression, hypotension, respiratory failure, seizures, coma and death. Seek immediate emergency/Poison Help (1-800-222-1222); clinical airway/cardiovascular support is required. Naloxone does not reverse promethazine depression; epinephrine must not treat promethazine-overdose hypotension because it can further lower BP. No home lavage, cathartic, charcoal or antidote protocol supplied.

MAO inhibitors with dextromethorphan have been associated with hyperpyrexia, hypotension and death; concomitant use is contraindicated. The selected combination label does not state a numeric post-MAO discontinuation interval: recent use requires pharmacist review. Alcohol, opioids, sedative/hypnotics, anesthetics, TCAs and tranquilizers intensify promethazine sedation/respiratory risk; avoid or clinician-adjust, never patient-led dose reduction. Other anticholinergic agents add adverse effects. Promethazine can alter certain hCG pregnancy tests and glucose-tolerance results.

The current Auvelity label identifies dextromethorphan-associated serotonin-syndrome risk with SSRIs/TCAs and other serotonergic medicines, and increased dextromethorphan exposure with strong CYP2D6 inhibitors. This supports pharmacist review of these combinations and prompt assessment of agitation, fever, tremor/twitching or autonomic instability. Auvelity has different ingredients/exposure: its doses, contraindication list and washout algorithm are not transplanted to this syrup. Do not combine dextromethorphan products independently.

Below 2 is contraindicated. Older children need lowest effective prescribed dosing, respiratory-depressant avoidance and activity supervision; pediatric Reye/hepatic symptoms and dehydration-associated dystonia deserve caution. Exact ages 12–17 lack an explicit row in this selected table and require dose review. Older adults may develop confusion/oversedation; start at the low end and monitor comorbid organ disease and interacting medicines.

Promethazine is hepatically metabolized and requires caution with impaired liver function; cholestatic jaundice is reported. The selected combination label provides no quantified renal/hepatic adjustment or dialysis clearance-based regimen. Debilitated, sedated or supine patients need caution with dextromethorphan. Do not infer safety from local OTC dextromethorphan dosing.

Combination reproduction studies were not conducted and adequate controlled human studies are absent; use only when clearly needed after benefit/risk assessment. Promethazine within 2 weeks of delivery may inhibit neonatal platelet aggregation; later developmental effects are unknown. The selected label says human milk excretion of either drug is unknown and advises nursing caution. No fetal-safety guarantee, universal milk-discard interval or pregnancy-letter category used as a modern risk conclusion.

Dextromethorphan acts centrally to raise cough threshold; promethazine blocks H1 receptors and has sedative/anticholinergic effects. The fixed oral product contains no codeine and does not acquire codeine analgesic indications. Lack of opioid analgesic action does not imply harmless overdose or freedom from misuse.

Both are absorbed orally and undergo hepatic metabolism. Dextromethorphan onset is roughly 15–30 minutes with effects around 3–6 hours; promethazine effects begin about 20 minutes and usually last 4–6 hours, sometimes up to 12 hours. These label effect times are not ingredient plasma half-lives. Modern dextromethorphan labeling supports CYP2D6-inhibition exposure concerns; no cough-syrup poor-metabolizer dosing algorithm inferred.

Assess cause/severity of cough, age, breathing disorders, dehydration, organ disease, CNS/movement symptoms and all prescriptions/OTC products. Review treatment response and persistent symptoms rather than escalating dose. Check for sedation, paradoxical excitation, respiratory depression and relevant blood/liver symptoms; no universal laboratory schedule asserted.

Measure doses in mL with an appropriate calibrated device. Never give to a child below 2; obtain explicit adolescent dosing review for this label. Avoid alcohol/other sedating or duplicate cough medicines and driving until effects known; supervise children’s hazardous activities. Report uncontrolled movements and limit sun exposure. Seek emergency care for slow breathing, severe unresponsiveness, seizure, NMS/serotonin-toxicity symptoms or overdose. Keep secure from children; no sharing or intentional high-dose use.

Concentration

Per 5 mL: dextromethorphan HBr 15 mg and promethazine HCl 6.25 mg.

Appearance / package

Clear yellow syrup; full PI lists 473 mL bottle, NDC 0116-4024-16.

Status

Prescription oral syrup, ANDA088864; clinical bottle label January 2025.

Selected excipients

Alcohol 7%, sucrose, flavorings and dyes; exact allergies/metabolic considerations require package review.

Per mL

Dextromethorphan HBr 3 mg/mL and promethazine HCl 1.25 mg/mL, derived from labeled 5 mL amounts.

Route scope

Oral syrup only; not promethazine injection/suppository, promethazine-codeine, standalone dextromethorphan or psychiatric fixed combinations.

Product differences

Other manufacturers’ salt strengths, alcohol/excipients, dose instructions and approval records require their own label review.

Store at 20–25°C, tightly closed and protected from light. Dispense in a tight light-resistant container. Keep securely away from children and use the actual package expiration; no universal after-opening discard interval is supplied.