Can Atarax (hydroxyzine) affect heart rate?

Can Atarax (Hydroxyzine) Affect Heart Rate?

Yes, hydroxyzine can affect heart rate, primarily through its anticholinergic properties and risk of QT prolongation, though direct heart rate effects are generally minimal at therapeutic doses.

Cardiovascular Effects of Hydroxyzine

QT Prolongation and Cardiac Arrhythmia Risk

The FDA drug label explicitly warns that hydroxyzine can cause QT prolongation and Torsade de Pointes (TdP), particularly in patients with pre-existing risk factors. 1 The majority of reported cases occurred in patients with:

• Pre-existing heart disease 1
• Electrolyte imbalances 1
• Concomitant use of other arrhythmogenic drugs 1
• Congenital long QT syndrome or family history 1
• Recent myocardial infarction 1
• Uncompensated heart failure 1
• Bradyarrhythmias 1

Direct Heart Rate Effects

Unlike medications specifically designed for rate control (beta-blockers, calcium channel blockers, digoxin), hydroxyzine does not have significant direct chronotropic effects. 2 As a first-generation antihistamine, hydroxyzine's cardiovascular profile differs substantially from rate-controlling agents that achieve 70% success in heart rate endpoints. 3

In clinical practice with cardiovascular patients, hydroxyzine has been shown to be well tolerated without significant heart rate alterations. A study of 55 patients with cardiovascular pathology (including acute MI, angina, and hypertension) receiving hydroxyzine 50 mg daily for 28 days demonstrated good tolerability and safety without reported heart rate complications. 4

High-Risk Situations Requiring Caution

Drug-Drug Interactions

Hydroxyzine must be used with extreme caution when combined with other QT-prolonging medications, including: 1

• Class IA antiarrhythmics (quinidine, procainamide) 1
• Class III antiarrhythmics (amiodarone, sotalol) 1
• Certain antipsychotics (ziprasidone, iloperidone, clozapine, quetiapine, chlorpromazine) 1
• Certain antidepressants (citalopram, fluoxetine) 1
• Certain antibiotics (azithromycin, erythromycin, clarithromycin, gatifloxacin, moxifloxacin) 1
• Other medications (pentamidine, methadone, ondansetron, droperidol) 1

Elderly Patients

Elderly patients require particular caution with hydroxyzine due to increased sensitivity and higher likelihood of decreased cardiac function. 1 The FDA label recommends:

• Starting at the low end of the dosing range 1
• Close observation for sedation and confusion 1
• Consideration of decreased hepatic, renal, or cardiac function 1
• Recognition that elderly patients are more likely to have concomitant cardiovascular disease 1

Clinical Decision Algorithm

Before Prescribing Hydroxyzine:

1. Screen for QT prolongation risk factors: Check for personal/family history of long QT syndrome, recent MI, heart failure, bradyarrhythmias 1

2. Review medication list: Identify all QT-prolonging drugs currently prescribed 1

3. Check electrolytes: Ensure potassium and magnesium are within normal limits 1

4. Consider baseline ECG: In patients with cardiovascular disease or multiple risk factors 1

If Hydroxyzine is Necessary in At-Risk Patients:

• Use the lowest effective dose 1
• Monitor for signs of arrhythmia (palpitations, syncope, dizziness) 1
• Consider ECG monitoring in high-risk patients 1
• Avoid combining with other QT-prolonging medications when possible 1

When to Avoid Hydroxyzine:

Discontinue hydroxyzine immediately if: 1

• Signs of AGEP (acute generalized exanthematous pustulosis) develop 1
• New cardiac symptoms emerge 1
• QT prolongation is detected on ECG 1

Comparison to Other Antihistamines

Second-generation antihistamines (fexofenadine, loratadine, cetirizine) are preferred over hydroxyzine for allergic conditions due to superior safety profiles, with minimal cardiovascular effects. 5 These agents lack the anticholinergic properties and QT prolongation risk associated with first-generation antihistamines like hydroxyzine. 5

Key Clinical Pitfalls

• Do not assume hydroxyzine is safe simply because it's commonly prescribed - the QT prolongation risk is real, though uncommon 1
• Do not overlook drug interactions - many commonly prescribed medications prolong QT interval 1
• Do not use standard adult doses in elderly patients - start low and titrate carefully 1
• Do not combine with other CNS depressants or rate-controlling medications without careful consideration 1