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Hayfever and Allergies

Allergic rhinitis and hay fever have an overall prevalence in the US of 10-15%., and this is something that increases in prevalence or incidence over time allergic rhinitis, hayfever, allergies. We don’t see a lot of hay fever in the first couple of years of life. It takes time to get sensitized to air allergens and develop symptoms. Which is actually good because we see so many colds.

Seasonal allergic rhinitis; you need to be able to differentiate between seasonal and perennial allergic rhinitis. And the seasonal is usually due to outdoor allergens. These are the common ones; they are the non-flowering, wind pollinated plants. Depending on which part of the country you are from, it may be a little earlier or a little later than what it might be here.

Diagnosis; and this is key. The diagnosis of allergic rhinitis is by history, not by physical exam. Again, the physical exam can be normal or it may help support your diagnosis. If you had to say which is the one single best test for allergic rhinitis, it’s a nasal smear for eosinophils. It is positive if there is more than 10% eosinophils. Now it may not be positive though if you have an acute infection, whether it’s a viral URI or sinusitis.

Skin testing; let’s talk about this real quickly. What we use now is a prick method rather than the intradermal method. The prick method is not quite as sensitive but it runs a much much lower risk of any serious side effects, especially anaphylaxis and it tends to have less false positives, so that’s the method of choice. The nice thing about skin testing is you get the results in 15-20 minutes. The disadvantage is that it is a little bit painful. One key thing about skin testing; a positive skin test means that you can form IgE to an antigen.

Food allergies; again, a positive test, say, to something like milk doesn’t necessarily mean you can’t tolerate milk. You have to always take positive tests and see if they are clinically important. Do they cause symptoms? And in general, only about one-third to one-half of those agents that you skin test positive to will make any difference clinically.

Vasomotor rhinitis; this is again more of an adult disease. This is typically adult women. There are often big time emotional problems going on and triggers.

Management of allergic rhinitis. Avoidance would be great, if you know what they are allergic to and you can avoid it, that would be wonderful. Then we’ll talk through all of these other areas here real quickly. Oral antihistamines are for most kids.

Second generation antihistamines; key thing, non-sedating. They don’t have the CNS effect. So you guys all know that. They also don’t have the anticholinergic effects. These are the ones that are on the market right now; Seldane, or terfenadine was taken off the market, fexofenadine which is a derivative of it actually is replacing it.

Topical antihistamines; there’s one on the market as azelastine, which interestingly has also some antiinflammatory effects. This may actually play a bigger role over time.

Topical decongestants work great. The problem is that patients use them too long and then we get into trouble with rhinitis medicamentosa. Or basically huge rebound and obstruction and edema when you stop the medication.

Oral decongestants; these we do tend to use. Again, the key thing that decongestants do is decrease the nasal obstruction. So this is why we combine these with antihistamines. Also we hope that the drowsiness that you get with the antihistamine is countered by the stimulation.

Ipratropium has been used for allergic rhinitis and other conditions like that. The key thing here is, all it really works against is rhinorrhea.

Topical cromolyn; long-term preventive agents. Again, the same kind of problem as with asthma. It has kind of a modest effect on the things that antihistamines usually deal with.

Topical corticosteroids; this is the only drug that works against all the aspects of allergic rhinitis. It includes the obstruction, and the sneezing, and the itching, and the rhinorrhea. And again, it works quickly. Maximal up in about two weeks.

Last thing, prevention of allergy. Is there some way we can avoid it in the first place? It has been shown for eczema but not for asthma or allergic rhinitis, but if you have a family where both parents are highly allergic, where mom and dad both have asthma and allergic rhinitis, that if you then have mom breast feed the child only for the first six months of life and not give the child any other foods -and actually if you put mom on a restricted diet also, so she’s not on milk or eggs or nuts or peanuts or other highly antigenic foods - that child will develop eczema at a later date in time and have a milder case than the control kids. So you don’t prevent the eczema from occurring but you do decrease the severity and the time of onset. It has not been shown with the other illnesses. The thing that you are going to see coming down the line over the next few years is that we can show now that the frequency and severity of asthma can be related to your