Safety of Combining Hydroxyzine and Doxepin

Primary Safety Concerns

The British Journal of Dermatology warns that combining hydroxyzine and doxepin requires significant caution due to additive CNS depression, anticholinergic effects, and potential cardiac risks including QT prolongation, and this combination should generally be avoided unless absolutely necessary with close monitoring 1
Both medications can prolong the QT interval, and their combination significantly increases the risk of dangerous cardiac arrhythmias including Torsade de Pointes, according to the British Journal of Dermatology 1
The British Journal of Dermatology specifically warns that antihistamines like hydroxyzine should not be taken concurrently with tricyclic antidepressants like doxepin due to arrhythmic properties 1
The combination of hydroxyzine and doxepin produces additive drowsiness that impairs driving ability and increases fall risk, particularly in elderly patients, as noted by the British Journal of Dermatology 1
The Journal of Clinical Sleep Medicine notes that combining sedating medications requires careful monitoring for excessive daytime sedation, with a strength of evidence based on clinical expertise 2

The British Journal of Dermatology recommends using hydroxyzine 10-50 mg at night as an adjunct to non-sedating antihistamines during the day, not in combination with other sedating agents, for pruritus management 1

Patients with renal impairment should have their hydroxyzine dose halved, and adding doxepin increases toxicity risk, according to the British Journal of Dermatology 1
Patients with hepatic disease should avoid both hydroxyzine and doxepin, as recommended by the British Journal of Dermatology 1

For pruritus, the British Journal of Dermatology recommends using hydroxyzine 10-50 mg at night with a non-sedating antihistamine during the day, based on moderate-strength evidence 1
For insomnia with pruritus, the British Journal of Dermatology suggests using hydroxyzine alone at bedtime, with a low strength of evidence based on clinical experience 1
For depression with pruritus, the British Journal of Dermatology recommends using doxepin alone at low doses for its antihistaminic properties, with a low strength of evidence based on clinical experience 1