Can I take Claritin (loratadine) in the morning and Xyzal (levocetirizine) at night?

Combining Loratadine (Claritin) and Levocetirizine (Xyzal): Not Recommended

You should not take both Claritin in the morning and Xyzal at night because this combination provides no additional therapeutic benefit over using a single second-generation antihistamine at higher doses, while unnecessarily increasing your medication burden and potential for side effects. 1

Why This Combination Is Not Recommended

Both Are Second-Generation Antihistamines

• Loratadine (Claritin) and levocetirizine (Xyzal) are both second-generation H1-antihistamines that work through the same mechanism—blocking histamine receptors to control allergic symptoms. 1
• Taking two different second-generation antihistamines simultaneously does not provide additive benefit because they compete for the same receptor sites. 1
• If standard doses of one second-generation antihistamine are insufficient, guidelines recommend increasing the dose of a single agent up to 4-fold rather than adding a second antihistamine. 2

Evidence Against AM/PM Combination Strategies

• The American Academy of Allergy, Asthma, and Immunology explicitly states that combining different antihistamines in an AM/PM dosing regimen is not a preferred strategy and does not improve outcomes. 3
• A high-quality randomized controlled trial demonstrated that adding hydroxyzine (a sedating antihistamine) at night to levocetirizine provided no additional symptom control compared to levocetirizine alone, while significantly increasing daytime somnolence. 4
• The widespread belief that combining antihistamines enhances efficacy is not supported by evidence. 4

What You Should Do Instead

If Symptoms Are Inadequately Controlled

• Increase the dose of a single second-generation antihistamine up to 4-fold before considering combination therapy. 2
• For levocetirizine (Xyzal), you can safely increase from the standard 5 mg daily up to 20 mg daily. 2
• For loratadine (Claritin), you can increase from 10 mg daily up to 40 mg daily, though doses above 10 mg may cause mild sedation. 1
• Approximately 75% of patients with difficult-to-treat allergic symptoms respond to these higher doses without increased side effects. 2

Choose the Right Single Agent

• If you require absolute avoidance of sedation (for driving, operating machinery, or fall risk), choose loratadine or fexofenadine, which are truly non-sedating at recommended doses. 1
• If you have failed loratadine therapy, switch to levocetirizine rather than adding it to loratadine. 1
• Levocetirizine is more potent than loratadine but carries a 13.7% risk of mild drowsiness compared to loratadine's negligible sedation risk. 1
• A large prescription-event monitoring study found that patients taking levocetirizine were 6.75 times more likely to experience drowsiness than those taking desloratadine (a drug similar to loratadine). 5

Add Intranasal Corticosteroids Instead

• If a single antihistamine at standard or increased doses does not control your symptoms, add an intranasal corticosteroid rather than a second antihistamine. 1
• Intranasal corticosteroids are more effective than antihistamines for controlling the full spectrum of allergic rhinitis symptoms, particularly nasal congestion, which antihistamines address poorly. 1

Important Sedation Considerations

Levocetirizine's Sedative Profile

• Levocetirizine causes mild drowsiness in approximately 13.7% of patients (versus 6.3% with placebo). 1
• Performance impairment can occur with levocetirizine even when you don't feel subjectively drowsy, meaning you may be functionally impaired without realizing it. 1
• The sedative effects of levocetirizine taken at night can persist into the next day due to its long half-life, potentially causing daytime drowsiness. 3

Timing Does Not Matter for Efficacy

• A randomized controlled trial of desloratadine (similar to loratadine) found no difference in efficacy whether the medication was taken in the morning or evening. 6
• The belief that evening dosing provides better nighttime symptom control is not evidence-based. 6

Common Pitfalls to Avoid

• Do not assume that taking two different antihistamines will double your symptom relief—they work through the same mechanism and do not provide additive benefit. 1
• Do not combine antihistamines as a cost-saving strategy—this approach is specifically discouraged by guidelines. 3
• Do not add levocetirizine at night if you drive or operate machinery the next morning—residual sedation can impair performance even when you feel alert. 3, 7
• Do not continue this combination if you started it on your own—speak with your physician about optimizing a single antihistamine or adding intranasal corticosteroids instead. 1

Special Populations

If You Have Renal Impairment

• Levocetirizine requires dose reduction in moderate renal impairment (50% dose reduction) and should be avoided in severe renal impairment. 1
• Loratadine should be used with caution in severe renal impairment but does not require specific dose reduction. 1

If You Are Elderly

• Older adults are more sensitive to antihistamine sedation and at increased risk for falls and cognitive impairment. 1
• Choose loratadine or fexofenadine over levocetirizine in elderly patients to minimize sedation risk. 1