Hydroxyzine for Itching: Dosage and Usage
For adults with pruritus, hydroxyzine 25 mg three to four times daily is the FDA-approved dosing regimen, though it is best reserved for nighttime use (25-50 mg at bedtime) due to its sedative properties, with non-sedating second-generation antihistamines preferred for daytime management. 1, 2
FDA-Approved Dosing
- Adults: 25 mg three to four times daily (t.i.d. or q.i.d.) for pruritus management due to allergic conditions such as chronic urticaria, atopic dermatitis, and contact dermatoses 1
- Children under 6 years: 50 mg daily in divided doses 1
- Children over 6 years: 50-100 mg daily in divided doses 1
- Dosage should be adjusted according to the patient's response to therapy 1
Recommended Clinical Approach
The optimal strategy is to use hydroxyzine strategically for nighttime itching while employing non-sedating antihistamines during the day. 2, 3
Treatment Algorithm by Severity:
- Mild or localized pruritus: Begin with topical treatments; add hydroxyzine 25 mg at bedtime only if nighttime symptoms are problematic 3
- Moderate pruritus: Use a non-sedating antihistamine (fexofenadine 180 mg, loratadine 10 mg, or cetirizine 10 mg) during the day, with hydroxyzine 25-50 mg at bedtime for nighttime relief 4, 2, 3
- Severe or widespread pruritus: Consider combination therapy with H1 and H2 antagonists (e.g., fexofenadine plus cimetidine), and if inadequate response, add GABA agonists like gabapentin or pregabalin 4, 3
Special Populations and Dose Adjustments
Critical dosing modifications are required in certain populations to avoid serious adverse effects:
- Moderate renal impairment: Reduce dose by 50% 2, 3
- Severe liver disease: Avoid hydroxyzine entirely due to inappropriate sedating effects 2, 3
- Early pregnancy: Contraindicated per UK manufacturer's guidelines 2, 3
- Elderly patients with cognitive impairment: Avoid due to anticholinergic effects and increased dementia risk; use second-generation antihistamines instead 2
Clinical Context and Guideline Recommendations
The British Association of Dermatologists recommends hydroxyzine specifically for short-term or palliative settings in generalized pruritus of unknown origin, acknowledging it as a sedative antihistamine option when other approaches have failed 4. This reflects the reality that hydroxyzine is not first-line therapy but has a role when nighttime sedation is beneficial 2.
Non-sedating antihistamines (fexofenadine, loratadine, cetirizine) should be tried before sedative antihistamines like hydroxyzine for daytime management 4. The American Academy of Dermatology supports this tiered approach, reserving hydroxyzine for nighttime use when its sedative properties provide dual benefit 2.
Real-world evidence demonstrates that hydroxyzine significantly improves both pruritus symptoms and quality of life over 12 weeks in patients with chronic pruritus, with good tolerability despite its sedating potential 5.
Important Caveats and Pitfalls
Watch for paradoxical worsening of dermatitis in ethylenediamine-sensitive patients:
- Hydroxyzine can worsen contact dermatitis in patients with sensitivities to ethylenediamine or phenothiazines due to cross-reactivity 6, 7
- If cutaneous lesions worsen on hydroxyzine therapy, discontinue immediately and consider patch testing 6, 7
- Generalized maculopapular eruptions can appear shortly after taking the drug in sensitized individuals 7
Avoid long-term continuous use in elderly patients due to increased risk of cognitive impairment and potential dementia risk with chronic first-generation antihistamine use 2.
When Hydroxyzine is Insufficient
If inadequate response after 2-4 weeks, consider:
- Increasing the antihistamine dose 4
- Adding H2 antihistamines in combination with H1 antagonists 4
- Switching to alternative treatments: paroxetine, fluvoxamine, mirtazapine, naltrexone, gabapentin (900-3600 mg daily), pregabalin (25-150 mg daily), or ondansetron 4
- For specific etiologies: phototherapy (BB-UVB) for uraemic or cholestatic pruritus 4