First-generation sedating antihistamine
ATC code: R06AB02 (Dexchlorpheniramine)
Brand names
Polaronil
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.
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.
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.
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.
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FDA category B. Large historical data set without described teratogenic effects; some cohorts note a weak association with pyloric stenosis when used in T3. For routine allergy in pregnancy, loratadine or cetirizine with better tolerability profile are preferred.
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.
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.
FDA category B. FDA category B. Large historical data set without described teratogenic effects; some cohorts note a weak association with pyloric stenosis when used in T3. For routine allergy in pregnancy, loratadine or cetirizine with better tolerability profile are preferred.
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.