First-generation sedating antihistamine
Brand names: Polaronil
Updated · Methodology
Adjunct
In acute allergic reactions and anaphylaxis, H1 antihistamines are adjuncts to intramuscular adrenaline (first-line) and oxygen. Parenteral dexchlorpheniramine 5 mg IV or IM relieves itching and urticaria but does not address hypotension or bronchospasm. 2020 emphasizes: antihistamines in anaphylaxis do not replace adrenaline and must not delay it.
Sources
ICD-10: T78.2 · ICD-11: 4A84
Second line
Per ARIA 2020 and 2022, not a preferred agent for allergic rhinitis – sedating H1 antihistamines are no longer first-line. Used in short courses when nocturnal sedation is welcome (severe itching, sleep disturbance). Standard dose 2 mg three to four times daily or 6 mg sustained-release at bedtime. In patients over 65, listed in 2023 Beers criteria – high risk of falls, confusion, and cognitive decline.
ICD-10: J30.9 · ICD-11: CA08.0
Second line
In chronic spontaneous urticaria, /GA²LEN 2022 lists second-generation antihistamines (bilastine, rupatadine, ebastine, levocetirizine) as first-line. Sedating first-generation H1 antihistamines are not preferred. Dexchlorpheniramine is used sparingly and short-term for severe itching with sleep disruption.
Sources
ICD-10: L50.1 · ICD-11: EB00.1
An antagonist of peripheral and central H1 histamine receptors. The active d-enantiomer of chlorpheniramine, with roughly double the potency. Crosses the blood-brain barrier readily – sedation and anticholinergic effects are marked. In Spain it is widely prescribed under the brand Polaramine, including parenterally for acute allergic reactions, although international guidance has shifted toward second-generation H1 antagonists as preferred agents.
AEMPS summary of product characteristics (section 4.6): injectable dexchlorpheniramine is contraindicated in the third trimester. Animal studies have shown no teratogenicity, so no malformations are expected in humans, and epidemiological studies appear to exclude any malformative effect of chlorpheniramine; under normal conditions of use it can be prescribed in the first two trimesters. Newborns of mothers treated long-term with high doses of anticholinergic drugs in the second and third trimesters have rarely shown symptoms related to atropine-like properties (abdominal distension, meconium ileus, delayed passage of meconium, difficulty starting feeds, tachycardia, neurological disorders). If the drug is given towards the end of pregnancy, the newborn's digestive and neurological functions are checked periodically.
Small amounts pass into milk but may cause infant drowsiness and reduce milk supply. Loratadine or cetirizine are preferred during lactation.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Verbatim lines from the interaction sections, in the language of the label
«- Pacientes que estén en tratamiento con inhibidores de la monoamino-oxidasa (IMAO) o durante las dos semanas siguientes a la interrupción de dicho tratamiento.»AEMPS, section 4.3 · Open on CIMA
«Use in Lower Respiratory Disease: Monoamine oxidase inhibitor therapy (See Drug Interaction section)»FDA, section 4 · Open on DailyMed
«U so concomitante contraindicado: -Asociaciones con otros depresores del sistema nervioso central (sedantes antidepresivos, barbitúricos, benzodiazepinas, clonidina y similares, hipnóticos, derivados…»AEMPS, section 4.5 · Open on CIMA
«U so concomitante contraindicado: -Asociaciones con otros depresores del sistema nervioso central (sedantes antidepresivos, barbitúricos, benzodiazepinas, clonidina y similares, hipnóticos, derivados…»AEMPS, section 4.5 · Open on CIMA
«U so concomitante contraindicado: -Asociaciones con otros depresores del sistema nervioso central (sedantes antidepresivos, barbitúricos, benzodiazepinas, clonidina y similares, hipnóticos, derivados…»AEMPS, section 4.5 · Open on CIMA
«U so concomitante contraindicado: -Asociaciones con otros depresores del sistema nervioso central (sedantes antidepresivos, barbitúricos, benzodiazepinas, clonidina y similares, hipnóticos, derivados…»AEMPS, section 4.5 · Open on CIMA
«U so concomitante contraindicado: -Atropina y otras sustancias atropínicas (antidepresivos de imipramina, antiparkinsonianos, anticolinérgicos, antiespasmódicos atropínicos, disopiramida…»AEMPS, section 4.5 · Open on CIMA
«U so concomitante contraindicado: -Asociaciones con otros depresores del sistema nervioso central (sedantes antidepresivos, barbitúricos, benzodiazepinas, clonidina y similares, hipnóticos, derivados…»AEMPS, section 4.5 · Open on CIMA
«U so concomitante contraindicado: -Asociaciones con otros depresores del sistema nervioso central (sedantes antidepresivos, barbitúricos, benzodiazepinas, clonidina y similares, hipnóticos, derivados…»AEMPS, section 4.5 · Open on CIMA
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Dexchlorpheniramine is evaluated for the following indications with varying evidence strength: Severe allergic reactions (evidence tier B), Allergic rhinitis (evidence tier C), Chronic urticaria (evidence tier D). See the full indication matrix with dosing and citations above on this page.
Common side effects of Dexchlorpheniramine (≥ 1 in 100): Marked drowsiness and sedation, Dry mouth and mucous membranes, Constipation, Urinary retention, Blurred vision, Tachycardia. See the Safety section for uncommon and serious reactions.
AEMPS summary of product characteristics (section 4.6): injectable dexchlorpheniramine is contraindicated in the third trimester. Animal studies have shown no teratogenicity, so no malformations are expected in humans, and epidemiological studies appear to exclude any malformative effect of chlorpheniramine; under normal conditions of use it can be prescribed in the first two trimesters. Newborns of mothers treated long-term with high doses of anticholinergic drugs in the second and third trimesters have rarely shown symptoms related to atropine-like properties (abdominal distension, meconium ileus, delayed passage of meconium, difficulty starting feeds, tachycardia, neurological disorders). If the drug is given towards the end of pregnancy, the newborn's digestive and neurological functions are checked periodically.
Small amounts pass into milk but may cause infant drowsiness and reduce milk supply. Loratadine or cetirizine are preferred during lactation.
Dexchlorpheniramine is contraindicated in: Hypersensitivity to dexchlorpheniramine and other alkylamines; Angle-closure glaucoma; Urinary retention with BPH; Epilepsy with active seizures (lowered seizure threshold); Age under 2 (paradoxical reactions and respiratory depression risk). Full list in the Safety section.
Direct links to regulator labels. Open in a new tab.
Dimenhydrinate, Diphenhydramine, Doxylamine/pyridoxine, Ebastine, Ketotifen, Promethazine, Cetirizine, Fexofenadine