GENERIC NAME: Hydroxyzine
BRAND NAMES: Atarax; Vistaril
DRUG CLASS AND MECHANISM: Hydroxyzine is an antihistamine with anticholinergic (drying) and sedative properties that is used to treat allergic reactions. Histamine is released by the body during several types of allergic reactions and -- to a lesser extent -- during some viral infections, such as the common cold. When histamine binds to its receptors on cells, it causes changes within the cells that lead to sneezing, itching, and increased mucus production. Antihistamines compete with histamine for cell receptors; however, when they bind to the receptors they do not stimulate the cells. In addition, they prevent histamine from binding and stimulating the cells. After ingestion, the molecule of hydroxyzine is changed slightly, and this changed hydroxyzine that also binds to cells. (This changed hydroxyzine-called an active metabolite--is cetirizine (Zyrtec), which is now an FDA- approved drug.) Though both hydroxyzine and cetirizine act as antihistamines, hydroxyzine causes sedation as a side effect, and cetirizine does not. Hydroxyzine was originally approved by the FDA in 1957.

GENERIC AVAILABLE: yes

PRESCRIPTION: yes

PREPARATIONS: Tablets: 10mg, 25mg, 50mg, 100mg. Capsules: 25mg, 50mg, 100mg. Syrup: 10mg per teaspoonful (5mL). Suspension: 25mg per teaspoonful (5mL).

STORAGE: Capsules, tablets, and liquids should be stored below 30℃ (86℃). Liquid should not be frozen, and should be shaken well prior to each use.

PRESCRIBED FOR: Hydroxyzine is used for the relief of nasal and non-nasal symptoms of various allergic conditions such as seasonal allergic rhinitis. Although antihistamines are the preferred class of drugs in allergic rhinitis, they only reduce symptoms by 40-60%. Hydroxyzine also is used as an aid for insomnia and to induce sedation prior to certain uncomfortable diagnostic or therapeutic procedures.

DOSING: Hydroxyzine has its maximal effect about 30 to 60 minutes after it is taken. Its effects last for 4 to 6 hours. Therefore, it is often prescribed to be taken every 4 to 6 hours as needed for relief of allergy-related symptoms. When used to combat insomnia, it is prescribed to be taken 30 to 60 minutes before bedtime as needed. Patients over the age of 60 years are especially sensitive to the sedating effects of hydroxyzine, and the dose should be reduced. Hydroxyzine can be taken with or without food.

DRUG INTERACTIONS: Hydroxyzine adds to (exaggerates) the sedating effects of alcohol and other drugs that can cause sedation such as the benzodiazepine class of anti-anxiety drugs (e.g., Valium, Ativan, Klonopin, Xanax), the narcotic class of pain medications and its derivatives (e.g. , Percocet, Vicodin, Dilaudid, Codeine, Darvon), the tricyclic class of antidepressants (e.g. Elavil, Tofranil, Norpramin), and certain antihypertensive medications (e.g., Catapres, Inderal). Hydroxyzine can also intensify the drying effects of other medications with anticholinergic properties (e.g., Bentyl, Urecholine, Probanthine, Elavil, Thorazine.) When using these drugs, the dose of hydroxyzine may require reduction, therefore.

PREGNANCY: A limited number of studies of hydroxyzine in pregnant women suggests that there may be a relationship between its use in the first trimester of pregnancy and congenital abnormalities in the fetus. Therefore, hydroxyzine should be avoided during the first trimester of pregnancy.

NURSING MOTHERS: It is not known if hydroxyzine is excreted into breast milk. In general, antihistamines are not recommended for use during breast-feeding because they can cause stimulation or seizures in newborns.

SIDE EFFECTS: Hydroxyzine can commonly cause sedation, tiredness, sleepiness, dizziness, disturbed coordination, drying and thickening of oral and other respiratory secretions, and stomach distress. Hydroxyzine may also cause confusion, nervousness, irritability, blurred vision, double vision, tremor, loss or appetite, or nausea. Hydroxyzine should be used with caution (if at all) in persons with narrow-angle glaucoma, prostatic hypertrophy (enlarged prostate gland), hyperthyroidism, cardiovascular disease, hypertension, and asthma.