SIDE EFFECTS
Adverse reactions which have been reported with the use of antihistamines are as follows:
Central Nervous System
Sedation and sleepiness (often transient), dizziness, disturbed coordination,
confusion, restlessness, excitation, nervousness, tremor, irritability, insomnia, paresthesias, neuritis,
convulsions, euphoria, hallucinations, hysteria, faintness.
Integumentary
Allergic manifestation of rash and edema, excessive perspiration, urticaria,
photosensitivity.
Special Senses
Acute labyrinthitis, blurred vision, diplopia, vertigo, tinnitus.
Cardiovascular
Hypotension, palpitation, tachycardia, extrasystoles, anaphylactic shock.
Hematologic
Hemolytic anemia, leukopenia, agranulocytosis, thrombocytopenia.
Digestive System
Cholestasis, hepatic failure, hepatitis, hepatic function abnormality, dryness of
mouth, epigastric distress, anorexia, nausea, vomiting, diarrhea, constipation, jaundice.
Genitourinary
Urinary frequency, difficult urination, urinary retention, early menses.
Respiratory
Dryness of nose and throat, thickening of bronchial secretions, tightness of chest and
wheezing, nasal stuffiness.
Miscellaneous
Fatigue, chills, headache, increased appetite/weight gain.
DRUG INTERACTIONS
MAO inhibitors prolong and intensify the anticholinergic effects of
antihistamines. Antihistamines may have additive effects with alcohol and other CNS depressants, e.g.
hypnotics, sedatives, tranquilizers, antianxiety agents.