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Thursday, April 24, 2008

The Best Antihistamines for Sneezing and Nasal Congestion

Photo Credit: Jon Lebkowsky

About 1 in every 5 people suffer from hay fever, also known as allergic rhinosinusitis by doctors, and I am one of them. Some people suffer all the time (perennial, persistent, constant), usually due to allergies to indoor allergens such as dust mites, molds, animal dander, or cockroaches. Others have allergic symptoms only during certain seasons, because they have become sensitized to grass, tree, or weed pollens. I’ve had hay fever since preschool days — a rather typical case.

When we lived in Minnesota, I only had symptoms during the summer, especially when I cut grass or raked leaves, but after moving to southern Arizona, I now have perennial allergic rhinitis (PAR), since weeds release pollen into the air almost any time of the year. After I get a cold or after I am exposed to a high dose of allergens (such as using a line-trimmer to cut weeds), my allergic rhinitis often worsens to include sinusitis.

As a child, my mom gave me Benadryl or Chlor-Trimeton pills. They worked for a few hours to suppress my sneezing, stuffy nose, and itchy eyes, but made me drowsy — probably a good side-effect from the viewpoint of my mother, considering my hyperactivity. In fact, these first generation antihistamines are also sold OTC (over-the-counter) as sleeping pills. I also got allergy shots and injections of my own urine (from a quack allergist), which “cured me” from complaining anymore about my allergies. I did avoid exposure to grass and weeds (also called secondary prevention) by not playing field sports (baseball, football, soccer) and by refusing to cut the grass.

I can’t tell you “what 9 out of 10 doctors recommend for hay fever,” but I can tell you what I’ve done, and tell you what’s been published from research studies (controlled clinical trials) of antihistamines. For many years, I got prescriptions for a second-generation, once-a-day, non-sedating antihistamine. They cost about 3 dollars per pill and even with insurance, the co-pay was over $100 per year, so I took them only when I had symptoms. Many others must have done the same, since the U.S. market for prescription antihistamines was then over 4 billion dollars per year.

Everything changed around Christmas, 2002 when the patent for Claritin expired and Wellpoint successfully petitioned the FDA to switch non-sedating antihistamines to OTC. Since then, I’ve taken generic loratidine every morning; and it only costs $20 a year (for a small bottle of 300 little white pills). Despite the doom and gloom prophecies of allergists and big pharma in 2001, it became a win-win situation. The quality of my life and others improved because we rarely have allergy symptoms anymore, and the profits of the manufacturers of loratidine improved (with 30% market share and 1.4 billion dollars in annual sales).

Allergy sufferers got another Christmas present in 2007 when the patent on Zyrtec, another non-sedating antihistamine, expired. Zertec is now available OTC for about a dollar a pill for the brand name product, while the generic cetirizine costs only $15 to $45 for a bottle of 90 tablets — enough to get through 3 months of the allergy season for those with seasonal allergic rhinitis. It’s also available as a chewable tablet or liquid for children (at a lower dose) and combined with a Decongestant in a capsule.

As an allergy sufferer in the United States, your choices have now been expanded: You can buy generic Claritin OTC, generic Zyrtec OTC, or ask your doctor for a prescription for Clarinex or Xyzal. To determine which is best antihistamine, I read the most recent studies, which are summarized in an excellent review by Doctors Lehman and Blaiss from the University of Tennessee (in the journal Drugs 2006), and a similar review, written for physician assistants, which you can download without cost.

In summary, second-generation antihistamines are the first-line therapy for both seasonal and perennial allergic rhinitis (SAR and PAR). They are very effective, very safe, and last for more than 24 hours. They are much less likely to cause sedation (drowsiness or fatigue) when compared to the old first generation antihistamines. For any of these drugs, the higher the dose, the more likely sedation will be noticed. At the recommended doses for adults, Zyrtec and its twin brother Xyzal are more likely to cause sedation (5-10%) when compared to the others (1-2%).

A small advantage for Zyrtec and Xyzal is that their onset of action may be shorter (about an hour) when compared to the others (1-3 hours). However, a somewhat slower onset of action is not a problem when these drugs are taken every morning (when you brush your teeth) to PREVENT the release of histamine in your nose and eyes later in the day. Antihistamines are much less effective if you wait to take them until you have symptoms.

Allegra (fexofenadine, still by prescription only) is slightly more effective in relieving itchy, watery, red eyes, and less likely to cause sedation at higher (off-label) doses, when compared to Claritin and Clarinex. Blood levels of Allegra are increased by about 40% if you take it with grapefruit juice, erythromycin (an antibiotic), or ketoconazole (an antifungal), but these drug-drug interactions are unlikely to significantly increase the risk of sedation from Allegra.

Bottom line, I will continue to take generic Claritin every morning, because it’s effective, doesn’t cause sedation at the recommended dose, and cheap. I may try generic Zyrtec when the cost drops towards that of generic Claritin. I will still keep a bottle of generic Benedryl for insect stings and severe allergic reactions, realizing that after taking it I will feel like a space cadet or sleepy. Despite heavy advertising, I personally see no reason to ask my doctor for a prescription for Clarinex, Allergra, or Xyzal, but I am sure that a few patients will feel that these expensive antihistamines are more effective.

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Posted by: Paul Enright MD at 6:59 pm

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