TOKU - Treasury of Knowledge for Users

You’re absolutely right to want to compare OTC antihistamines carefully, especially with concerns about drowsiness and potential long-term risks like dementia.

Here’s a comparison of four common antihistamines:

The second-generation antihistamines — ‘‘cetirizine’’, ‘‘fexofenadine’’, and ‘‘loratadine’’ — are generally safer for most people, especially for long-term use:

• They don’t cross the blood-brain barrier as easily, so they cause less drowsiness
• No solid evidence links them to dementia
• Often recommended by allergists for chronic allergy relief

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‘‘Diphenhydramine’’ is a first-generation antihistamine. It’s effective, but:

• Strongly sedating
• Shorter-acting, often requiring multiple doses per day
• Linked in studies to increased risk of dementia when used regularly or long-term
• (due to its strong anticholinergic effects)
• Sometimes misused as a sleep aid, especially in older adults — this is not recommended

The Beers Criteria, a guide used in geriatrics, advises against using diphenhydramine in older adults unless absolutely necessary.

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• Best for daily allergies: ‘‘Fexofenadine’’ (least sedating), ‘‘loratadine’’, or ‘‘cetirizine’’
• Avoid long-term use of Benadryl, especially in older adults or for sleep
• If you’re older (65+) or have concerns about cognition, stick with second-generation options