Seasonal allergies

OB/GYN News, Sept 1, 2003 by Michele G. Sullivan

Seasonal allergies affect up to 40 million people in the United States and cost an estimated $4.5 billion in medical care annually. In addition to causing almost 4 million missed school and workdays every year, these allergies can be associated with the development of asthma, rhinosinusitis, and otitis media.

Diagnosis. Symptoms are most common during times of high pollination: early spring to early summer and again in late summer and into the fall until the first killing frost. However, in temperate climates allergy symptoms can occur year round.

In allergy-prone individuals, the pollen of trees, grasses, and flowering plants can create an inflammatory cascade that results in a number of unpleasant symptoms: wheezing, sneezing, coughing, headache, nasal congestion, impaired sense of smell, itching of the nose or oropharynx, and allergic conjunctivitis.

Although seasonal allergies may exhibit similar symptoms to a cold or upper respiratory infection, they are not accompanied by fever and they tend to persist, rather than resolving in 7-10 days.

Opinions vary about specialist referral. Some studies show that primary care physicians diagnose allergies correctly less than 50% of the time. This suggests that early referral to an allergist results in earlier appropriate treatment and a decrease in the development of allergy-related illnesses such as asthma.

Serologic testing is a good way to ascertain that symptoms are caused by a histamine-mediated reaction. Consider referral to an allergist for testing and immunotherapy if the patient has severe symptoms, including ocular symptoms, or if symptoms continue despite Pharmacotherapy.

Treatment. During times of high pollen count, advise patients to keep windows and doors dosed at home and work and to use air conditioning, which filters out most of the pollen. Patients should refrain from outdoor activities when pollen counts are high, especially before noon, when pollination peaks. After outdoor activities, they should shower and change clothes. Since clothing picks up lots of pollen, tell patients to dry their laundry in a vented dryer, not by hanging it on an outside line.

The best first-line pharmacotherapy for most patients with seasonal allergy is a combination of an oral antihistamine and a nasal corticosteroid. Corticosteroids relieve nasal congestion without the side effects of a decongestant.

Oral antihistamines are effective at controlling allergic rhinitis, itching, and allergic conjunctivitis. Their adverse events (sedation, psychomotor and cognitive impairment, confusion, irritability, dry mouth, urinary retention, and changes in appetite) are associated with their ability to penetrate the central nervous systems and with their antiserotonin and anticholinergic effects.

Sedation is most problematic with the older antihistamines; even in the absence of sedation, psychomotor and cognitive slowing can occur with these drugs. These problems are not as common with the newer drugs, which have less CNS penetration and thus, limited serotonin and cholinergic effect.

Antihistamines are often combined with a decongestant to relieve nasal pressure. However, because decongestants can increase heart rate, they are contraindicated in patients with hypertension, cardiac arrhythmias, or other cardiac conditions. Decongestants also can cause insomnia.

For best results, antihistamine treatment should be started before the patient's symptoms develop or at the start of her allergy season and be continued throughout the season.

Topical antihistamines, in the form of eye drops and nasal sprays, are very effective in relieving acute symptoms of ocular itching and allergic rhinitis.

Nonsedating antihistamine choices include fexofenadine and loratadine (with or without a decongestant). Loratadine (Claritin) is now available without a prescription.

The less-sedating antihistamines include Acrivastine / pseudoephedrine HCl (Semprex-D) and cetirizine (Zyrtec), which is also available with pseudoephedrine HCl.

Mast cell inhibitors have few side effects, but they're not as effective as antihistamines since they affect only one portion of the inflammatory cascade. To achieve maximum effect, they must be started at least 2 weeks before the allergy season begins and must be used four times daily throughout the season. This kind of dosing schedule makes compliance a challenge.

Sources: DR. PAMELA GEORGESON, an allergist in private practice in Chesterfield Township, Mich.; and DR. JONATHAN BERNSTEIN of the University of Cincinnati.