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

No — Sudafed is not an antihistamine. It is a decongestant, though it’s often used alongside antihistamines to treat cold or allergy symptoms.

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Sudafed is the brand name for:

• ‘‘Pseudoephedrine’’ – the original version, available behind the pharmacy counter
• ‘‘Phenylephrine’’ – an over-the-counter version that is less effective

It’s classified as a nasal decongestant.

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Decongestants like Sudafed:

• Constrict blood vessels in the nasal passages
• Reduce swelling and improve airflow
• Do not block histamine

Antihistamines:

• Block histamine, the chemical responsible for sneezing, itching, and watery eyes

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• Can raise blood pressure – not ideal for people with hypertension or heart disease
• May cause jitters, restlessness, or insomnia
• Pseudoephedrine is regulated — you must request it from the pharmacy counter and show ID
• Phenylephrine, found in many OTC products, has been shown to be ineffective when taken orally (per FDA findings)

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Some allergy medications combine antihistamines with Sudafed, such as:

• Claritin-D (loratadine + pseudoephedrine)
• Zyrtec-D (cetirizine + pseudoephedrine)

These treat both:

• Histamine symptoms – sneezing, itching, watery eyes
• Nasal congestion

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• Sudafed is a decongestant, not an antihistamine
• Best for nasal congestion, not for sneezing or itchy eyes
• Can be used alongside antihistamines for broader relief
• Use with caution if you have heart conditions, high blood pressure, or insomnia