Side effects of hydroxyzine may include drowsiness, dizziness, upset stomach, headache or chest congestion, according to MedlinePlus. Hydroxyzine may also cause reddening skin or dry nose, mouth and throat.
More serious side effects of hdroxyzine requiring immediate medical attention include muscle weakness, trouble breathing or elevated anxiety, according to MedlinePlus.
Doctors typically prescribe hydroxyzine to treat itching due to allergies, nausea, anxiety and symptoms of alcohol withdrawal, according to MedlinePlus. It is available in tablet, capsule, syrup and suspension form, and patients typically take a dose three to four times per day. Doctors typically do not prescribe hydroxyzine to children under 12 years of age.