What are common antihistamines for managing allergic symptoms?

Common Antihistamines for Managing Allergic Symptoms

Second-generation antihistamines are generally preferred over first-generation antihistamines for the treatment of allergic rhinitis due to their improved safety profile and reduced sedative effects. 1

First-Generation vs. Second-Generation Antihistamines

First-Generation Antihistamines

• Include diphenhydramine, chlorpheniramine, and brompheniramine 1
• Associated with significant sedation, performance impairment, and anticholinergic effects 1
• May cause dry mouth, urinary retention, and other anticholinergic side effects 1
• Can be dangerous for older adults due to increased risk of falls, fractures, and cognitive impairment 1
• Should be avoided in children under 6 years of age due to safety concerns and reported fatalities 1

Second-Generation Antihistamines

• Include cetirizine, desloratadine, fexofenadine, levocetirizine, and loratadine 1
• Provide effective relief of allergic symptoms with minimal or no sedation 1
• Have better safety profiles, especially in children 1
• Generally preferred for treatment of allergic rhinitis 1

Specific Second-Generation Antihistamines

Sedative Properties Comparison

• Non-sedating at recommended doses: fexofenadine, loratadine, and desloratadine 1
• May cause sedation at recommended doses: cetirizine and intranasal azelastine 1
• May cause sedation at higher than recommended doses: loratadine and desloratadine 1

Common Second-Generation Options

• Cetirizine (10 mg):

  • Provides 24-hour relief of sneezing, runny nose, itchy/watery eyes, and itchy throat/nose 2
  • May cause mild drowsiness in some patients (13.7% vs 6.3% for placebo) 1
  • Approved for children 6 years and older 2

• Levocetirizine (5 mg):

  • Provides 24-hour relief of allergic symptoms 3
  • The active enantiomer of cetirizine with similar efficacy profile 1

• Loratadine and Desloratadine:

  • Non-sedating at recommended doses 1
  • Effective for allergic rhinitis symptoms 1

• Fexofenadine:

  • No sedative properties even at higher than FDA-approved doses 1
  • Effective for allergic rhinitis symptoms 4

Special Considerations

Children

• Second-generation antihistamines (cetirizine, desloratadine, fexofenadine, levocetirizine, loratadine) have been shown to be well-tolerated with good safety profiles in young children 1
• First-generation antihistamines should be avoided in children under 6 years due to safety concerns 1
• Between 1969 and 2006, there were 69 reported fatalities in children associated with first-generation antihistamines 1

Elderly Patients

• Older adults are more sensitive to the psychomotor impairment from first-generation antihistamines 1
• Increased risk for falls, fractures, subdural hematomas, and adverse anticholinergic effects 1
• Second-generation antihistamines are strongly preferred in this population 1

Pregnancy

• Best to avoid all antihistamines in pregnancy, especially during the first trimester 1
• When antihistamine therapy is necessary, chlorphenamine is often chosen due to its long safety record 1

Effectiveness for Specific Symptoms

• Oral antihistamines are effective in reducing rhinorrhea, sneezing, and itching associated with allergic rhinitis 1
• They have limited effect on nasal congestion 1
• May reduce symptoms of allergic conjunctivitis often associated with allergic rhinitis 1
• H1 antihistamines are useful for relieving itching and urticaria but do not relieve respiratory symptoms in anaphylaxis 1

Common Pitfalls and Caveats

• First-generation antihistamines can cause performance impairment even when patients don't feel drowsy 1
• Continuous treatment is more effective than intermittent use for seasonal or perennial allergic rhinitis 1
• Intranasal corticosteroids are more effective than antihistamines for controlling the full spectrum of allergic rhinitis symptoms 1
• Antihistamine-decongestant combination products are not effective for symptoms of upper respiratory tract infections in young children 1
• No single second-generation antihistamine has been conclusively found to achieve superior overall response rates 1