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    DEA Class; OTC

    Common Brand Names; Histex, Vanahist PD, Histex PD Drops, M-Hist PD, Vanaclear PD

    • Antihistamines, 1st Generation

    First generation histamine-1 receptor antagonist

    Indicated for temporary relief of rhinorrhea, sneezing, itchy nose, throat, or eyes owing to have fever or other upper respiratory allergies or allergic rhinitis

    Patients taking sedatives or tranquilizers

    Hypersensitivity; note that cross allergenicity may occur between chemically similar antihistamines

    • Blurred vision
    • Sedation
    • Urinary retention
    • Constipation
    • Xerostomia

    May cause CNS depression, resulting in impaired physical or mental abilities; caution patients about performing tasks that require mental alertness (eg, driving, operating machinery)

    Antihistamines may cause excitation in young children

    Discontinue and contact physician if symptoms persist beyond 7 days or are accompanied by fever

    Discontinue and contact physician if nervousness, dizziness, or sleeplessness occur

    Do not exceed recommended dose

    Discontinue therapy and ask doctor if new symptoms occur

    Ask a healthcare professional before self-medication if experiencing breathing problems such as emphysema or chronic bronchitis, glaucoma, enlarged prostate (difficulty urinating)


    Limited data exist

    Generally, antihistamines are considered low risk during pregnancy; however, exposure near birth of premature infants was associated with increased risk of retrolental fibroplasia


    Distributed in human breast milk; small, occasional doses are not expected to cause adverse effects in infant

    Histex: 2.5 mg (5 mL) PO q6hr

    Vanahist PD or M-Hist PD: 2.5 mg (4 mL) PO q6hr


    oral liquid

    • 0.5mg/mL (Histex)
    • 0.625mg/mL (Vanahist PD, M-Hist PD)