Does hydroxyzine help with allergies?

Hydroxyzine for Allergies

Hydroxyzine is effective for treating allergic symptoms but is not recommended as a first-line treatment due to significant sedation and anticholinergic effects. 1

Efficacy and Mechanism

Hydroxyzine is a first-generation H1 receptor antihistamine that has demonstrated effectiveness in treating allergic conditions:

• In controlled clinical trials, hydroxyzine has been shown to effectively suppress symptoms of seasonal allergic rhinitis 2
• During periods of high pollen counts, hydroxyzine-treated patients experienced significantly more symptom-free days or days with only mild symptoms compared to placebo 2
• It works by antagonizing histamine H1 receptors, which are involved in the allergic response

Limitations and Side Effects

Despite its effectiveness, hydroxyzine has important limitations:

• Highly sedating with extended anticholinergic effects 1
• Can cause significant cognitive impairment due to its ability to cross the blood-brain barrier 1
• Common side effects include:
  • Drowsiness (especially initially)
  • Dry mouth
  • Cognitive impairment (particularly in elderly patients)
  • Potential impairment of learning and school performance in children 1

Recommendations for Use

The American Academy of Allergy, Asthma, and Immunology recommends:

• Using hydroxyzine with caution due to its ability to cause significant sedation and impairment of psychomotor performance 1
• Considering second-generation (non-sedating) antihistamines as preferred alternatives for allergic conditions 1
• If hydroxyzine is used for allergies:
  • Start with lower doses and gradually increase as tolerated
  • Monitor for anticholinergic effects, especially in elderly patients
  • Be aware that tolerance to sedative effects may develop over time 2

Special Populations

Extra caution is needed in certain populations:

• Elderly patients: Increased risk of cognitive decline, falls, and anticholinergic effects 1
• Children: May impair learning and school performance 1
• Pregnant women: Contraindicated during early pregnancy 1
• Patients with liver or kidney impairment: Use with caution and consider dose adjustments 1

Comparative Effectiveness

When comparing hydroxyzine to other antihistamines:

• Hydroxyzine has been shown to be more effective than second-generation antihistamines in suppressing histamine-induced skin reactions 3
• More than 50% of hydroxyzine-treated individuals showed negative test reactions to histamine compared to only 10-20% with second-generation antihistamines 3
• However, cetirizine (a metabolite of hydroxyzine) provides similar efficacy with markedly lower incidence of sedation 4

Clinical Pearls

• Hydroxyzine can be used as an antihistamine in the management of drug reactions to platinum agents 5
• In rare cases, patients may develop hypersensitivity to hydroxyzine itself, including urticaria or even anaphylaxis 6
• Patients with sensitivities to ethylenediamines may experience worsening of dermatitis with hydroxyzine use 7

Bottom Line

While hydroxyzine is effective for allergic symptoms, its significant sedative and anticholinergic effects make second-generation antihistamines (cetirizine, loratadine, etc.) more appropriate first-line choices for most patients with allergies. Reserve hydroxyzine for cases where sedation is acceptable or beneficial (e.g., allergic conditions with significant sleep disturbance or anxiety).