Sunday, July 21, 2024

Two main categories of antihistamine medicines: sedating, non-sedating agents.


Q: Every summer, my nose runs, and my eyes itch from my allergies. Which antihistamine is best?

When you come in contact with something you’re allergic to, your body releases histamine, which triggers a cascade of symptoms we associate with an allergic reaction: nasal congestion, runny nose, itchy, watery eyes, and sinus pressure.

Antihistamines counteract the effects of histamine by triggering an opposite action in your body. Which antihistamine is best depends on how well it relieves your symptoms and how drowsy it makes you.

There are 2 main categories of antihistamine medicines: sedating and non-sedating agents. Sedating antihistamines are older drugs and usually cause some drowsiness and drying action. That drying action helps relieve a runny nose and watery eyes.

Antihistamines don’t work the same in everyone. Some will relieve your allergy symptoms better than others. Many people have to try more than one before finding one that works well while causing less drowsiness.

Older antihistamines like Benadryl® (diphenhydramine), doxylamine, chlorpheniramine, and triprolidine cause drowsiness in most people. If this concerns you, start with one of the newer drugs.

Newer antihistamines like Claritin® (loratadine) and Allegra® (fexophenadine) rarely cause drowsiness. Unfortunately, these allergy medicines are less effective at drying runny noses or watery eyes than older agents like diphenhydramine and triprolidine.

Two non-sedating options are loratadine (Claritin®, Alavert®) and fexofenadine (Allegra®). Loratadine is taken once daily, while Allegra® is available in 2 formulas, once daily and twice daily.

Cetirizine (Zyrtec®) is another once-daily allergy medicine. Closely related to the prescription drug hydroxyzine, cetirizine is more likely to cause some drowsiness than Claritin® or Allegra®.

If you are suffering from a runny nose, Zyrtec® works better than the non-sedating allergy remedies.

Try one of the older antihistamines if Claritin®, Allegra®, or Zyrtec® aren't relieving your runny nose or itchy, watery eyes. The most powerful is Benadryl®(diphenhydramine). It is more potent against severe allergy symptoms but can cause significant drowsiness in many people.

In fact, diphenhydramine is sold as a non-prescription sleeping pill as Tylenol PM® and Sominex II. Unlike newer drugs for allergies, Benadryl® needs to be taken 3 to 4 times daily for best results. If your allergies wake you up with a stuffy nose and sinus pressure, consider taking Benadryl® only at bedtime and using a less sedating agent during the day.

Other older antihistamines still available include chlorpheniramine, brompheniramine, and triprolidine. Triprolidine causes a little less drowsiness than the other older antihistamines, and it dries up a runny nose for me better than anything else.

Triprolidine was previously only available in combination with a decongestant, as Actifed®. My favorite allergy medication is the version of Actifed® (AprodineTM), which contains triprolidine and the original form of Sudafed®, pseudoephedrine.

Years ago, before nasal sprays were available, surgeons used them to tame runny eyes and noses when doing surgery. I prefer it because it relieves my runny nose, watery eyes, and nasal congestion without much drowsiness.

In the past, triprolidine has been challenging to find. It has just been released as a single agent, Flonase Night Time Allergy Relief®. It is already in Mucinex® Night Shift Cold and Flu, Night Shift Severe Cold and Flu, and Night Shift Sinus.

I do not recommend Mucinex® Night Shift Severe Cold and Flu or Sinus because they contain phenylephrine. Phenylephrine is not an effective decongestant, and increases blood pressure without relieving nasal congestion.

Here Are 5 Tips on Choosing an Antihistamine:

1.           Don’t delay.

Antihistamines work best if you take them as soon as you are exposed to an allergy trigger. They are less effective after your nose stuffs up and your eyes start itching.

2.           Choose not to snooze.

Non-sedating antihistamines like loratidine (Claritin®) or fexofenadine (Allegra®) are safest if you have to drive or use machinery.

3.           Don’t give up.

If your first antihistamine choice doesn't help you, try another one. It's not unusual to get little relief from one antihistamine but have good results with a different one.

4.           Consider a combo.

Consider adding a nasal spray or decongestant to your antihistamine. Flonase® nasal spray and combining triprolidine and pseudoephedrine as Actifed® or AprodineTM can address runny and stuffy nose symptoms.

5.           Try triprolidine.

Although the combination of pseudoephedrine and triprolidine has been hard to find, triprolidine is now available as Flonase® Night Time Allergy Relief, taken every 4-6 hours. As an older antihistamine, it can cause drowsiness. Try it at home before driving to determine if you are affected, or take it only at night. Some, like me, notice no drowsiness at all.

Dr. Louise Achey, Doctor of Pharmacy, is a 43-year veteran of pharmacology and author of Why Dogs Can’t Eat Chocolate: How Medicines Work and How YOU Can Take Them Safely. Get clear answers to your medication questions at her website and blog,

2023 Louise Achey



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