What is the recommended dosing for hydroxyzine (antihistamine) in adult patients with anxiety?

Hydroxyzine Dosing for Anxiety in Adults

For adults with anxiety, hydroxyzine should be dosed at 50-100 mg four times daily (QID), as specified by the FDA-approved labeling. 1

Standard Dosing Regimen

• Initial and maintenance dose: 50-100 mg QID for symptomatic relief of anxiety and tension associated with psychoneurosis and as an adjunct in organic disease states where anxiety is manifested 1
• The total daily dose typically ranges from 200-400 mg per day divided into four doses 1
• Dosage should be adjusted according to the patient's response to therapy 1

Evidence Supporting Efficacy

• Fixed-dose studies demonstrate that 50 mg/day is effective for generalized anxiety disorder (GAD), showing superiority over placebo on all anxiety measures from the first week of treatment 2, 3
• A 3-month double-blind study confirmed that hydroxyzine 50 mg/day maintains efficacy throughout 12 weeks of treatment with a mean HAM-A score reduction of -12.16 compared to -9.64 for placebo (p=0.019) 4
• Hydroxyzine demonstrates comparable efficacy to benzodiazepines (chlordiazepoxide and bromazepam) and buspirone for GAD 5, 4

Clinical Considerations

Onset and Duration of Effect

• Anxiolytic effect begins during the first week of treatment and is maintained throughout the treatment period 2, 3
• No rebound anxiety or withdrawal symptoms occur after abrupt discontinuation 2

Tolerability Profile

• Sleepiness/drowsiness is the most common side effect (28%), appearing during the first week and progressively diminishing with continued treatment 2
• Other side effects include dry mouth (14%), weight gain (12%), loss of concentration (9%), and insomnia (9%) 2
• Drowsiness is more frequent with hydroxyzine compared to other anxiolytics like buspirone, but overall tolerability is comparable to benzodiazepines 5, 4

Important Caveats

• Use lower doses (0.25-0.5 mg for benzodiazepines as reference) in frail or elderly patients with medical conditions, though specific hydroxyzine dose reductions for elderly are not explicitly stated in the FDA label 6
• Alpha-adrenergic antagonism activity may pose risks when combined with other alpha-blocking medications like risperidone, potentially increasing risk of adverse effects 7
• The FDA label allows for initial intramuscular administration followed by oral dosing if needed 1

Advantages Over Benzodiazepines

• Lack of dependency potential and absence of organ toxicity based on extensive clinical experience 3
• No withdrawal syndrome upon discontinuation, unlike benzodiazepines 2
• Beneficial effects on sleep without the addiction risk associated with benzodiazepines 3