What is standard patient teaching about hydroxyzine (antihistamine) when prescribing it?

Standard Patient Teaching for Hydroxyzine

When prescribing hydroxyzine, counsel patients that this medication will cause drowsiness and impair their ability to drive or operate machinery, particularly during the first week of treatment, and they must avoid alcohol and other sedating medications due to dangerous additive effects. 1

Critical Safety Warnings

CNS Depression and Performance Impairment

• Warn patients explicitly not to drive or operate dangerous machinery while taking hydroxyzine, as it significantly impairs reaction times and causes drowsiness 1, 2
• Advise against simultaneous use of alcohol, narcotics, non-narcotic analgesics, barbiturates, or any other CNS depressants, as hydroxyzine potentiates their effects 1
• Inform patients that drowsiness is most prominent during the first week but typically diminishes with continued use 3
• Note that subjective feelings of alertness do not reliably predict actual performance impairment—patients may feel fine but still have prolonged reaction times 2

Cardiac Risk

• Inform patients to seek immediate medical attention if they experience palpitations, dizziness, or fainting, as hydroxyzine can cause QT prolongation and potentially fatal heart rhythm abnormalities 1
• This risk is higher in patients with pre-existing heart disease, electrolyte imbalances, or those taking other medications that affect heart rhythm 1

Serious Skin Reactions

• Instruct patients to stop hydroxyzine immediately and contact their provider if they develop any new rash, fever with pustules, or worsening of skin conditions, as this may indicate acute generalized exanthematous pustulosis (AGEP) 1

Common Side Effects to Expect

• Drowsiness/sleepiness (occurs in 28% of patients, most prominent in first week) 3
• Dry mouth (14% of patients) 3
• Weight gain (12% of patients) 3
• Loss of concentration (9% of patients) 3
• Irritability (reported in studies) 2

Dosing Strategy to Minimize Side Effects

• Consider taking hydroxyzine at bedtime rather than in divided doses to minimize daytime drowsiness and performance impairment while maintaining therapeutic effect 4
• For urticaria, hydroxyzine can be added at night (10-50 mg) to a non-sedating antihistamine taken during the day 5, 6
• Adjust timing so highest drug levels occur when symptoms are anticipated 5

Special Population Warnings

Pregnancy

• Hydroxyzine is specifically contraindicated during early pregnancy 5, 6, 7
• If antihistamine therapy is absolutely necessary during pregnancy, chlorphenamine is preferred due to its longer safety record 6

Renal Impairment

• Patients with moderate renal impairment (creatinine clearance 10-20 mL/min) require dose reduction to half the standard dose 5, 6
• Hydroxyzine should be avoided entirely in severe renal impairment (creatinine clearance <10 mL/min) 5, 6, 7

Hepatic Impairment

• Hydroxyzine should be avoided in severe liver disease due to inappropriate sedating effects 5, 6

Elderly Patients

• Start elderly patients on low doses and monitor closely for confusion, over-sedation, and fall risk 7, 1
• Elderly patients have increased sensitivity to psychomotor impairment 7

Potential Sleep-Related Effects

• Some patients may experience nightmares or disturbed dreaming, particularly with bedtime dosing 7
• If nightmares occur, consider taking the medication earlier in the evening or reducing the dose 7

Duration and Discontinuation

• Hydroxyzine can be stopped abruptly without rebound anxiety or withdrawal symptoms 3
• Therapeutic effect begins within the first week of treatment 3

Drug Interactions to Avoid

• Avoid concomitant use with medications that prolong QT interval, including certain antiarrhythmics (quinidine, amiodarone), antipsychotics (ziprasidone, quetiapine), antidepressants (citalopram, fluoxetine), and antibiotics (azithromycin, erythromycin) 1