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Dexchlorpheniramine, the d-isomer of the racemic compound chlorpheniramine, is two times more active than chlorpheniramine. Dexchlorpheniramine does not prevent the release of histamine, but rather, competes with free histamine for binding at the H1-receptor sites, and competitively antagonizes the effects of histamine on H1-receptors in the GI tract, uterus, large blood vessels, and bronchial muscle. Blockade of H1-receptors also suppresses the formation of oedema, flare, and pruritus that result from histaminic activity. Since dexchlorpheniramine binds to central and peripheral H1-receptors, sedative effects are likely to occur. H1-antagonists are structurally similar to anticholinergic agents and therefore possess the potential to exhibit anticholinergic properties of varying degrees.


Symptomatic treatment of perennial and seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, mild uncomplicated allergic skin manifestations of urticaria and angioedema. Dexchlorpheniramine may relieve itching due to skin conditions such as allergic eczema, pruritus ani, pruritus vulvae, atopic dermatitis, contact dermatitis, insect bites, dermographism and drug reactions, including serum sickness.

[edit] DOSAGE

2 mg tables:

  • Adults and children over 12 years: One tablet every 6 hours

Dexchlorpheniramine Syrup (2mg per 5 mL)

  • Adults and children over 12 years: 5 mL every 6 hours
  • Children 6 – 12 years: 2 – 4 mL every 6 - 8 hours
  • Children 4 - 6 years: 1.75 – 2 mL every 6 - 8 hours
  • Children 2 – 4 years: 1.25 – 1.75 mL every 6 - 8 hours

Dexchlorpheniramine Syrup is not to be used in children under 2 years of age.


  • newborns and premature infants.
  • patients taking monoamine oxidase inhibitors (MAOIs)
  • patients with a history of hypersensitivity to dexchlorpheniramine, to other drugs of similar chemical structure.


Dexchlorpheniramine may cause drowsiness and may add to the effects of alcohol. Drowsiness may continue the following day. Those affected should not drive or operate machinery; alcohol should be avoided

Dexchlorpheniramine should be used with caution in patients with:

  • narrow-angle glaucoma
  • stenosing peptic ulcer
  • prostatic hypertrophy
  • bladder neck obstruction
  • pyloroduodenal obstruction
  • cardiovascular disease including hypertension
  • increased intraocular pressure
  • hyperthyroidism
  • use with caution in patients with renal or hepatic impairment
  • seizures

Dexchlorpheniramine may cause photosensitivity in some patients.


The following interactions with Dexchlorpheniramine have been noted:

  • central nervous system (CNS) depressants (alcohol, sedatives, opioid analgesics, hypnotics) may cause an increase in sedative effects of Dexchlorpheniramine
  • concomitant administration with tricyclic antidepressants (TCAs) may result in additive antimuscarinic activity
  • monoamine oxidase inhibitors (MAOIs) may prolong and intensify the anticholinergic and CNS depressive effects of some antihistamines and may cause a decrease in blood pressure
  • oral anticoagulants may have their actions decreased by antihistamines.



Dexchlorpheniramine should be used during the first two trimesters of pregnancy only if clearly needed.

Dexchlorpheniramine maleate should not be used in the third trimester of pregnancy because newborn and premature infants may have severe reactions to antihistamines.

Use in Lactation : Dexchlorpheniramine is excreted in breast milk. Therefore caution should be exercised when administered to nursing mothers.


Slight to moderate drowsiness is the most frequent side effect of dexchlorpheniramine.