Antihistamines (Oral) (cont.)

Pharmacy Author:
Medical and Pharmacy Editor:

Antihistamines also differ in how long they work. Long-acting antihistamines provide symptom relief for up to 8-12 hours, while shorter acting agents last for up to 4 hours but begin working faster.

What are examples of oral antihistamines available in the US?

First generation antihistamines include

  • brompheniramine
  • chlorpheniramine (Chlor-Trimeton)
  • diphenhydramine (Benadryl)
  • doxylamine (found in many OTC sleep aids including Unisom)
  • carbinoxamine (Karbinal ER)

Second generation antihistamines include

What are the side effects of oral antihistamines?

First generation antihistamines are used less often to treat allergies because they cause significant sedation. First generation antihistamines also should be used cautiously in older adults as they are more susceptible to their anticholingeric side effects including

Medically Reviewed by a Doctor on 7/9/2015

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