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Allergy sufferers have long faced a no-win situation with traditional antihistamine medications: sneeze and itch your way through seasonal allergies or take antihistamines and live in a fog instead. Antihistamines stop allergy symptoms by reducing or blocking histamines—chemicals the body releases in response to an allergic trigger. Histamines cause the stuffy nose; itchy, watery eyes; and rashy skin that are the hallmarks of an allergic reaction.
While antihistamines can reduce these symptoms, they can cause unpleasant side effects, too. Allergy medication such as Benadryl and Chlor-Trimeton cause drowsiness, dry mouth, dizziness, blurred vision, nausea, and restlessness. Newer-generation nondrowsy antihistamines such as Clarinex and Zyrtec have been presented as having fewer antihistamine side effects and are often described as non-drowsy allergy medication.
A recent study, however, indicates that non-drowsy allergy medicine doesn’t hold true; the best allergy medicine and newer-generation antihistamines tested caused daytime drowsiness, too.
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Comparing New and Old Antihistamines for Drowsiness and Mood
Results of the study, “Assessment of the Effects of Antihistamine Drugs on Mood, Sleep Quality, Sleepiness, and Dream Anxiety,” were published in the International Journal of Psychiatry in Clinical Practice.
Ninety-two patients with chronic allergies were administered standard therapeutic doses of newer generation antihistamines, including cetirizine (Zyrtec), levocetirizine (Xyzal), and desloratadine (Clarinex), or older drugs, including hydroxyzine (Atarax) and pheniramine (Avil).
The effects of these drugs on mood, daytime sleepiness, and some measures of sleep quality were assessed before and after one month of treatment. The researchers compared the effects of all drugs on daytime sleepiness and mood, noting that very few studies so far have made these comparisons.
All Antihistamine Drugs Increase Daytime Drowsiness
The results showed that all the drugs studied, not just the first generation antihistamines, were associated with increased daytime sleepiness. Furthermore, patients receiving Zyrtec reported higher depression, anxiety, and fatigue scores than those who received the other newer generation drugs.
How to Avoid Antihistamine Drowsiness and Treat Your Allergies Naturally
Take these steps if you’re interested in bypassing the effects of antihistamines:
- Reduce exposure by showering off pollens and irritants every night.
- Use a neti pot with saline solution twice a day to rinse allergens from your sinuses.
- Equip your home with HEPA (high-efficiency particulate air) filters.
- Take other steps to allergy proof your home, such as using dust mite-proof pillow and mattress covers, keeping windows closed and using air conditioning during high-pollen days, keeping pets out of the bedroom, and vacuuming twice a week.
- Take fish oil (1000 mg EPA/DHA per day), quercetin (500 mg twice a day), and n-acetyl-cysteine (400 mg twice a day) to boost your body’s ability to fight allergens.
- Eat foods from the sulforaphane-rich Brassica family (e.g., broccoli, cauliflower, kale, Brussels sprouts, and cabbage) daily.
- Try taking an extract of the herb butterbur (50 mg three times a day). Comparisons of butterbur to prescription drugs such as fexofenadine (Allegra) and cetirizine (Zyrtec) have reported similar efficacy.
- Read more about natural allergy treatment using herbs and supplements here.
There’s no need to suffer antihistamine-induced drowsiness, depression, or anxiety day in and day out. The best antihistamine may be one of the many natural allergy treatments available. Give these options a try and you may not need those allergy medicines after all.
Q: What are the most common side effects of antihistamines?
A: Although effective, antihistamines can cause side effects, depending on the type of medication you use. First-generation antihistamines—such as chlorpheniramine (Chlor-Trimeton®) and diphenhydramine (Benadryl®)—can cause drowsiness, dry mouth, dry eyes, headache, and abdominal pain. Second-generation antihistamines—such as cetirizine (Zyrtec®), fexofenadine (Allegra®) and loratadine (Claritin®)—typically are less likely to cause these side effects.
Antihistamines tend to cause side effects more often in older adults, especially when used with other sedating medications or alcohol. Men with benign prostate enlargement (BPH) should avoid first-generation antihistamines, as the drugs can worsen urinary symptoms and potentially cause urinary retention.
Be aware that many cough and cold remedies contain antihistamines, and using them in combination with standalone antihistamines may increase their effects. Also, antihistamines are often combined with decongestants, which can increase blood pressure and cause other side effects. Ask your healthcare provider whether antihistamines are safe for you, based on your medical condition.
Originally published in 2016, this post has been updated.
 Int J Psychiatry Clin Pract. 2014 Mar 27. [Epub ahead of print]