What are the recommended antihistamines (anti-histamine medications) for symptomatic relief of itching or allergic reactions?

Recommended Antihistamines for Symptomatic Relief of Itching and Allergic Reactions

For symptomatic relief of itching and allergic reactions, second-generation (non-sedating) antihistamines such as cetirizine, loratadine, and fexofenadine are recommended for daytime use, while first-generation antihistamines like hydroxyzine or diphenhydramine can be used for nighttime relief due to their sedative properties. 1, 2

First-Line Antihistamine Options

Second-Generation (Non-Sedating) Antihistamines

• Cetirizine 10mg daily is recommended for daytime use due to its relatively rapid onset of action compared to other second-generation antihistamines 1, 3
• Loratadine 10mg daily provides 24-hour relief with minimal sedation 1, 4
• Fexofenadine does not impair psychomotor or cognitive skills and shows no dose-related increase in sedation 5

First-Generation (Sedating) Antihistamines

• Hydroxyzine is recommended for nighttime use due to its sedative properties that can help with sleep disruption from itching 2
• Diphenhydramine 25-50mg can be used for short-term relief of itching and urticaria, particularly at night 1, 6

Clinical Decision Algorithm

For Daytime Relief:

• Start with a second-generation antihistamine (cetirizine 10mg, loratadine 10mg, or fexofenadine) 1, 7
• Cetirizine has the fastest onset of action among the newer antihistamines and may be preferred when rapid relief is needed 5
• These medications provide relief for symptoms including itching, sneezing, runny nose, and watery eyes 3

For Nighttime Relief:

• Use first-generation antihistamines like hydroxyzine or diphenhydramine 2
• The American Academy of Dermatology recommends hydroxyzine specifically for nighttime itching due to its sedative properties 2

For Inadequate Response:

• Consider combination therapy with H1 and H2 antagonists (e.g., fexofenadine and cimetidine) 1
• For severe or refractory cases, consider adding other agents like paroxetine, mirtazapine, gabapentin, or pregabalin 1

Important Considerations and Cautions

Efficacy Limitations

• H1 antihistamines are useful only for relieving itching and urticaria; they do not relieve stridor, shortness of breath, wheezing, GI symptoms, or shock 1
• Antihistamines should be considered adjunctive therapy and should not be substituted for epinephrine in anaphylaxis 1

Special Populations

• Avoid hydroxyzine in elderly patients with cognitive impairment due to anticholinergic effects 2
• Avoid hydroxyzine in early stages of pregnancy 2
• Reduce hydroxyzine dosage in patients with moderate renal impairment 2
• Avoid hydroxyzine in severe liver disease due to inappropriate sedating effects 2

Side Effect Considerations

• First-generation antihistamines cause sedation and cognitive and psychomotor impairment, which may contribute to decreased awareness of symptoms 1, 5
• Second-generation antihistamines have significantly less sedation and psychomotor impairment than first-generation counterparts 8, 7
• Cetirizine may cause some sedation, though less than first-generation antihistamines 5

Specific Clinical Scenarios

For Chronic Urticaria:

• Loratadine, cetirizine, or mizolastine appear to be treatments of choice 8
• For symptomatic dermatographism, consider combination of an antihistamine and an H2 antagonist 8

For Generalized Pruritus of Unknown Origin:

• Consider non-sedative antihistamines such as fexofenadine or loratadine before sedative agents 1
• Use sedative antihistamines like hydroxyzine only in short-term or palliative settings 1
• H1 and H2 antagonists may be used in combination for enhanced effect 1

By following this evidence-based approach to antihistamine selection, clinicians can optimize symptomatic relief while minimizing adverse effects for patients with itching and allergic reactions.