Recommended Approach for Screening Antihistamines in Allergic Symptoms
Second-generation oral antihistamines should be the first-line choice for patients with allergic rhinitis presenting with primary complaints of sneezing and itching. 1
Types of Antihistamines and Their Selection
First vs. Second-Generation Antihistamines
- Second-generation antihistamines are strongly preferred over first-generation antihistamines due to their improved safety profile and reduced sedative effects 2
- First-generation antihistamines (diphenhydramine, chlorpheniramine, brompheniramine) cause significant sedation, performance impairment, and anticholinergic effects such as dry mouth and urinary retention 1, 2
- First-generation antihistamines can cause performance impairment even when patients don't subjectively feel drowsy 2
Recommended Second-Generation Antihistamines
- Fexofenadine, loratadine, and desloratadine are non-sedating at recommended doses 2, 3
- Cetirizine and intranasal azelastine may cause sedation at recommended doses 2
- Fexofenadine maintains its non-sedating properties even at higher than FDA-approved doses, making it truly non-sedating 2, 3
- Continuous treatment is more effective than intermittent use for seasonal or perennial allergic rhinitis 1
Screening Algorithm for Antihistamine Selection
Step 1: Assess Symptom Profile
- For patients with primary complaints of sneezing and itching: oral second-generation antihistamines 1
- For patients with nasal congestion as primary complaint: intranasal corticosteroids are more effective than antihistamines 1
- For patients with allergic conjunctivitis symptoms: oral antihistamines can provide relief 1
Step 2: Consider Patient-Specific Factors
- For patients who operate machinery or drive: fexofenadine is preferred due to minimal sedative effects 3
- For elderly patients: avoid first-generation antihistamines due to increased risk of falls, fractures, and cognitive impairment 2
- For children under 6 years: second-generation antihistamines are well-tolerated with good safety profiles 2
Step 3: Evaluate Comorbidities
- For patients with asthma: assess for comorbid conditions that may influence treatment choices 1
- For patients with chronic urticaria: regular (not as-needed) use of second-generation antihistamines is recommended 4
Administration and Dosing Considerations
Oral Antihistamines
- Oral antihistamines have rapid onset of action and are effective for reducing rhinorrhea, sneezing, and itching 1
- They have limited effect on nasal congestion 1
- Second-generation antihistamines are available over-the-counter, providing potential cost savings 1
Intranasal Antihistamines
- Intranasal antihistamines may be useful alternatives to oral antihistamines but may cause sedation in some patients 1
- They may be perceived to have a bitter taste 1
- For nasal symptoms, intranasal antihistamines have shown equality or superiority to oral antihistamines 1
Monitoring and Follow-up
- Monitor for sedation, especially at the initiation of intranasal antihistamines 1
- Follow up to assess response and side effects 1
- Be aware that antihistamines have limited role in treating nonallergic rhinitis syndromes 1
Common Pitfalls to Avoid
- Avoid using first-generation antihistamines due to significant sedation and anticholinergic effects 2
- Don't assume all second-generation antihistamines have the same sedation profile; there are important differences 2
- Avoid using antihistamines as monotherapy for nasal congestion, as they have limited effect on this symptom 1
- Don't use antihistamines for extended periods without evaluating their effectiveness 1