Is it safe to take Atarax (hydroxyzine) and fexofenadine together?

Concurrent Use of Atarax (Hydroxyzine) and Fexofenadine

Taking hydroxyzine (Atarax) and fexofenadine together is generally not recommended due to the redundant antihistaminic effects and increased risk of sedation, though it may be appropriate in specific clinical scenarios under medical supervision.

Pharmacological Considerations

Mechanism of Action

• Hydroxyzine (Atarax): First-generation H1 antihistamine with significant sedative properties and anticholinergic effects 1
• Fexofenadine: Second-generation, non-sedating H1 antihistamine that does not cross the blood-brain barrier 2, 3

Potential Issues with Combination

1. Redundant H1 receptor blockade

   • Both medications target the same H1 histamine receptors
   • Adding a second antihistamine provides minimal additional benefit for most conditions 1

2. Increased risk of side effects

   • Hydroxyzine causes significant sedation and cognitive impairment 4
   • Combined use may increase risk of sedation and impaired performance 1

3. Pharmacodynamic considerations

   • Hydroxyzine has been shown to be more effective at suppressing histamine-induced skin reactions than second-generation antihistamines like fexofenadine 5
   • Fexofenadine has been demonstrated to cause significantly less drowsiness than other antihistamines 6

Clinical Scenarios

When Combination Might Be Considered

1. Severe urticaria or allergic reactions

   • British guidelines suggest that adding a sedating antihistamine at night (e.g., hydroxyzine 10-50 mg) to a non-sedating daytime antihistamine may help patients sleep better 1
   • However, this likely provides little additional clinical effect if the H1 receptor is already saturated 1

2. Timing-based approach

   • Fexofenadine during daytime (non-sedating)
   • Hydroxyzine at night (when sedation may be beneficial) 1

When Combination Should Be Avoided

1. Elderly patients

   • Hydroxyzine should be avoided in elderly patients due to risk of cognitive decline 1
   • Sedative antihistamines are not recommended for elderly patients with pruritus 1

2. Patients with impaired driving or cognitive tasks

   • Hydroxyzine significantly impairs cognitive and psychomotor function 4
   • Fexofenadine alone does not impair driving performance 4

3. Pregnancy

   • Hydroxyzine is specifically contraindicated during early stages of pregnancy 1
   • Limited data on fexofenadine during pregnancy 1

4. Hepatic impairment

   • Hydroxyzine should be avoided in severe liver disease 1

5. Renal impairment

   • Dose adjustments required for both medications 1

Practical Recommendations

1. For most allergic conditions:

   • Choose either hydroxyzine OR fexofenadine, not both
   • Fexofenadine is preferred for daytime use due to lack of sedation 3

2. For severe, refractory urticaria:

   • Consider fexofenadine during day and hydroxyzine at night if approved by healthcare provider 1
   • Monitor for excessive sedation or cognitive impairment

3. For patients with sleep disturbance:

   • Consider timing-based approach with non-sedating fexofenadine during day and hydroxyzine at night 1

Important Precautions

• Avoid driving or operating machinery if using hydroxyzine, especially when combined with other medications 4
• Do not exceed recommended doses of either medication
• Be aware that hydroxyzine has significant anticholinergic effects that can cause dry mouth, urinary retention, and constipation 1
• Fexofenadine is considered truly non-sedating even at higher doses 3

Bottom Line

While there are specific scenarios where the combination might be used under medical supervision, for most patients, using either hydroxyzine OR fexofenadine alone would be more appropriate to minimize side effects while maintaining therapeutic benefit.