What is hydroxyzine used for?

What Hydroxyzine Is Used For

Hydroxyzine is a first-generation antihistamine primarily used as a nighttime adjunct (10–50 mg at bedtime) to non-sedating antihistamines for pruritus and urticaria, and secondarily for short-term anxiety relief and preoperative sedation. 1, 2

FDA-Approved Indications

Hydroxyzine is officially approved for: 2

• Symptomatic relief of anxiety and tension associated with psychoneurosis and as an adjunct in organic disease states where anxiety is present
• Management of pruritus due to allergic conditions including chronic urticaria, atopic dermatitis, and contact dermatoses, as well as histamine-mediated itching
• Preoperative and postoperative sedation as an adjunct to anesthesia

The FDA notes that effectiveness as an antianxiety agent beyond 4 months has not been systematically assessed. 2

Primary Clinical Use: Pruritus and Urticaria

Recommended Treatment Algorithm

Step 1: Initiate non-sedating antihistamine monotherapy 1, 3

• Start with a second-generation antihistamine (cetirizine 10 mg, loratadine 10 mg, or fexofenadine 180 mg) taken once daily in the morning
• Provide at least two alternative options, as individual response varies
• Continue for 2–4 weeks to assess response

Step 2: Escalate non-sedating antihistamine dose if inadequate 1

• Increase the second-generation antihistamine up to four-fold (e.g., cetirizine up to 40 mg daily) before adding any sedating agent
• This approach provides better overall urticaria control than adding hydroxyzine

Step 3: Add hydroxyzine only for persistent nighttime symptoms 1, 3

• Prescribe hydroxyzine 10–50 mg at bedtime (most commonly 25–50 mg) when nocturnal itching disrupts sleep despite optimized daytime antihistamine dosing
• The bedtime-only regimen minimizes daytime sedation while providing sustained effects into the next day due to hydroxyzine's long half-life
• Hydroxyzine does not improve overall urticaria control compared with higher-dose non-sedating antihistamines alone, but may help some patients achieve better sleep

Critical Caveat: Never Use as First-Line Monotherapy

Hydroxyzine must not be used as sole therapy or prolonged monotherapy for pruritus/urticaria because its sedating properties and performance impairment outweigh benefits when used alone. 1, 3

Secondary Use: Anxiety Disorders

Hydroxyzine 50 mg has demonstrated anxiolytic efficacy in generalized anxiety disorder, with superiority over placebo from the first week and greater cognitive improvement compared to lorazepam in controlled trials. 4 However, the FDA emphasizes that long-term use (>4 months) lacks systematic evaluation. 2

Tertiary Use: Insomnia

A 2023 systematic review of 207 patients found mixed efficacy for hydroxyzine 25–100 mg at bedtime in sleep onset, maintenance, and quality. 5 Hydroxyzine may be considered as a short-term option for adults with insomnia when previous therapy was ineffective, not tolerated, or contraindicated, but additional long-term studies are needed. 5

Other Documented Uses

• Seasonal allergic rhinitis: Hydroxyzine 150 mg/day suppressed symptoms during ragweed season, though drowsiness and dry mouth were initially frequent. 6
• Interstitial cystitis: Open-label data showed 40% symptom reduction (55% in patients with allergies), suggesting usefulness especially with documented allergies or bladder mast cell activation. 7
• Delirium: A 2025 retrospective study found intravenous hydroxyzine monotherapy had a superior rate of delirium improvement (23.9%) compared to haloperidol (8.5%), though this is not a standard indication. 8

Mandatory Dose Adjustments in Special Populations

Renal Impairment 1, 3

• Moderate impairment (CrCl 10–20 mL/min): Reduce dose by 50%
• Severe impairment (CrCl <10 mL/min): Avoid hydroxyzine entirely

Hepatic Disease 1, 3

• Severe hepatic disease: Absolute contraindication—avoid due to risk of excessive sedation and potential hepatic encephalopathy

Elderly Patients 1, 2

• Start at the low end of dosing range (10 mg at bedtime) due to age-related declines in hepatic, renal, and cardiac function
• Hydroxyzine is specifically listed among anticholinergic medications that should be avoided or deprescribed in older adults due to fall risk, fractures, subdural hematomas, cognitive impairment, and delirium
• Approximately 80% of elderly patients experience sedation and significantly prolonged reaction times even at standard doses

Pregnancy 1, 3

• Contraindicated in early pregnancy (first trimester)—hydroxyzine is the only antihistamine with this explicit contraindication

Critical Safety Warnings

Performance Impairment and Driving Risk 1

• Drivers taking hydroxyzine are 1.5 times more likely to be responsible for fatal motor-vehicle accidents compared to non-users
• Approximately 80% of patients experience sedation and objective performance impairment, even when they report feeling alert
• Impairment persists into the following day due to long half-life and active metabolites
• Chronic therapy does not lead to tolerance—sedative effects persist with continued use
• Associated with reduced work performance, impaired learning in children, and higher rates of occupational accidents

Anticholinergic Effects 1, 2

• Common effects include dry mouth, urinary retention (including acute retention), constipation, blurred vision, and increased intraocular pressure
• Use caution in patients with prostatic hypertrophy, elevated intraocular pressure, or cognitive impairment

Cardiac Risk: QT Prolongation 2

• Post-marketing reports of QT prolongation and Torsade de Pointes, particularly in patients with pre-existing heart disease, electrolyte imbalances, or concomitant arrhythmogenic drug use
• Use with caution in patients with congenital long QT syndrome, family history of long QT syndrome, recent myocardial infarction, uncompensated heart failure, and bradyarrhythmias
• Avoid concomitant use with Class 1A antiarrhythmics (quinidine, procainamide), Class III antiarrhythmics (amiodarone, sotalol), certain antipsychotics (ziprasidone, quetiapine, chlorpromazine), certain antidepressants (citalopram, fluoxetine), and certain antibiotics (azithromycin, erythromycin, moxifloxacin)

Drug Interactions 2

• Potentiates CNS depressants (narcotics, non-narcotic analgesics, barbiturates, alcohol)—reduce dosage of concomitant CNS depressants when used with hydroxyzine
• Avoid combination with tricyclic antidepressants (e.g., doxepin) due to additive anticholinergic effects, CNS depression, and arrhythmic properties 9
• Does not interfere with digitalis action and may be used concurrently 2

Dermatologic Reaction 2

• Rare cases of Acute Generalized Exanthematous Pustulosis (AGEP)—discontinue at first appearance of skin rash or worsening of pre-existing skin reactions
• Avoid cetirizine or levocetirizine in patients who experienced AGEP with hydroxyzine due to cross-sensitivity risk

Common Pitfalls to Avoid

• Do not use AM/PM split dosing of hydroxyzine and non-sedating antihistamines—hydroxyzine's long half-life causes significant daytime impairment even with bedtime-only dosing 1
• Do not prescribe for daytime use—sedation and performance-impairing effects are clinically significant even when taken only at night 1
• Do not use for prolonged monotherapy—impairs concentration, work performance, and increases occupational accidents 1, 3
• Do not use in delirium management—sedating and anticholinergic properties make it inappropriate despite one positive retrospective study 1
• Do not combine with other sedatives or anticholinergics without careful risk-benefit assessment and close monitoring 1, 9, 2