Up to 20% -- 1 out of 5 -- people in the United States have some sort of respiratory allergy. (I heard this estimate from an allergist, mind you... but the number of patients I see with respiratory allergies is pretty high, so he may very well be right.) Although the most common -- and most infamous -- respiratory allergen is ragweed pollen, which is responsible for hay fever, there are thousands of other allergens floating around in the air we breathe, and many people are susceptible to more than one. (I myself am allergic to at least 42 different airborne allergens -- and that's out of only 46 to which I was tested for reactions.)
There are things we can do about allergic rhinitis, though. Although you may not think so if you have had it long enough, there are many different treatments available for hay fever and other respiratory allergies. If you have been suffering for a long time, ask your doctor about some of the newer therapies available.
Allergic rhinitis, unlike viral rhinitis (the common cold), is caused by allergic reactions of the mucous membranes in your nose and airway to substances in the air.
The mucous membranes in your nose and throat -- and throughout your respiratory tract, all the way down to your lungs -- contain cells that produce mucus (which helps trap small particles of foreign matter so that it can be swept out of the body), as well as cells with cilia (small hairs that do the actual sweeping). These cells can be made to work harder by certain antibodies, known collectively as immunoglobulin E or IgE, and by chemicals such as histamine which are released by immune-system cells when they are stimulated by allergens. Exposure to allergens eventually results in increased mucus production, edema (swelling) of the mucous membranes, itching, and sneezing; some of this reaction is almost immediate, while other parts of the reaction can occur as much as 2-8 hours after you run into the allergen.
Note that you must actually be allergic to something before these reactions happen. Allergy to a substance is a kind of immune reaction, and, as with viral and bacterial immunity, you need to be exposed to the allergen before you start having immune reactions. It's unusual for very small children (less than 1 year old) to have respiratory allergies, simply because they haven't been exposed to the allergens long enough to become immune/allergic to them. If you are prone to allergies, you tend to be allergic to more things as you grow older because you have been exposed to more things for more time. (Like me: I had no allergy problems until I was almost 20. And then the faucet opened... ) However, many children with respiratory allergies grow out of them as they grow older.
The allergens that can cause allergic rhinitis are many and varied. The notorious ones are from plants whose pollens are airborne: these include many weeds, including ragweed (which is the specific trigger for classic "hay fever"), many trees, and many grasses. Molds are also capable of triggering allergic rhinitis: a moldy basement or bathroom can make you miserable, but so can outdoor molds. Animal dander (usually cats and dogs, but also many other animals) can trigger runny noses and sneezing as well, and dust mites (microscopic insects which live in bedding and carpet and feed on the microscopic skin cells we normally shed) are a major allergic trigger for many people.
Specific offenders vary by season. Weeds are usually a problem from late summer to the first hard frost. Grasses usually pollinate in the late spring and early summer, while trees pollinate in the spring. Outdoor molds are largely a late winter/early spring problem, but this is weather-dependent: in near-tropical areas (such as the southern United States) pollens may present an allergy problem year-round, and in relatively warm winters molds are a constant source of irritation to many of us. The spring and summer of 2011, especially in the Midwestern United States, have been very rainy, and many patients I know have had springtime-like allergy problems that have extended far into the summer because of all the rain and the molds that multiply and are stirred up every time we get another heavy rainfall.
In the last 15-20 years we have started using many new treatments for hay fever and other forms of allergic rhinitis, and for those of us who have it life during the "season" has become much more tolerable. (Believe me -- I have tried all of the treatments I describe here on myself, and after them -- including 5 years of allergy shots -- I no longer notice when hay fever season opens. You may not get such results yourself, but if you have hay fever or other seasonal allergies, you should talk to your doctor about different treatment options. Most people do not have to suffer during the season.)
Antihistamines are medicines that block the effect of histamine. Since histamine is the major chemical agent in allergic reactions, this often provides relief.
Antihistamines have been around for a long time. Unfortunately, the older antihistamines also affect one's brain, making you very sleepy. In fact, diphenhydramine (Benadryl®), a very potent antihistamine, is so sedating that it is also sold as an over-the-counter sleeping pill. Because of this sedative effect, you should NEVER take the older antihistamines when driving or using machinery, and you should never take the older antihistamines with any other medicine -- or anything else (including alcohol!) -- that may also cause sedation, unless your doctor specifically tells you to do so. (A General Rule: never mix drugs for any reason, unless your doctor tells you that you need to mix them and can mix them safely.)
There are newer antihistamines available that do not sedate you nearly as well as the older agents. In fact, they rarely sedate people at all -- although you should still be careful about driving and machinery until you and your doctor know that the particular medicine you're taking will not sedate you. The first of these medicines on the market had some hazardous interactions with other drugs (notably certain antibiotics), but the three most commonly used non-sedating antihistamines, loratidine, cetirizine, and fexofenadine, have not yet been reported to be a problem in combination with other medicines (although, as Another General Rule, you should always tell your doctor about every medicine you are taking, even the over-the-counter medicines, so that you and your doctor can be sure that there won't be any hazardous interactions.) Loratidine, cetirizine, and fexofenadine are reportedly so safe, in fact, that they are available over the counter. Each of these three medicines works quite well in those people for whom it does work. However, there are many people for whom one or more of these medicines does not work well -- another reason to talk to your doctor about these medicines.
Steroids, which are hormones normally produced by your body, help regulate many bodily functions including inflammation. Giving extra steroids for a short period of time may help reduce inflammation; in particular, steroids can help open an asthmatic patient's airways by reducing the inflammation in the airway walls. Other steroid hormones help regulate such things as reproduction, blood pressure, and mineral balances (like sodium and potassium, which are crucial to many important functions), body development, and growth.
Steroids have many drawbacks. Your body must make steroids all the time for many processes to work right. If you take oral (or injectable) steroids for too long, your steroid-making system will think it's not needed any more and shut down, and if you then face a situation where you need the steroids (any kind of stress, including surgery) all sorts of things can go wrong -- like your blood pressure, to take one example.
We can use oral steroids to relieve allergic rhinitis. However, we try not to
do so unless someone is really miserable. Unlike, for example,
asthma (which can be
life-threatening), allergic rhinitis will make you miserable but does not
endanger you. However, we can give steroids as nasal sprays; when sprayed
into the nose these steroids work on and in the nose and upper airway without
being absorbed by the rest of the body. (Many nasal steroids are ones that
are broken down immediately by your digestive system, so they can't be
absorbed by the body.) We haven't yet seen firm evidence of side effects if
you use nasal steroids for a long time (but that doesn't mean that there are
none). I use nasal steroids on myself before and during the ragweed-pollen
season, when my allergies are at their worst, as well as one of the oral
The mast cells are part of the lining of the air passages; they are part of
your immune system, reacting immediately to allergens and other obnoxious
stimuli. The mast cells release many different substances when they are
stimulated, including histamine.
Cromolyn is a drug that "stabilizes" airway mast cells, making them
less prone to releasing histamine and other substances in response to
allergens. Because of this, cromolyn sprayed into the nose regularly helps to
prevent the nasal inflammation and runny nose of allergic rhinitis. It does
not relieve the congestion and drainage immediately. It only helps
prevent them -- and it works best if and only if you use it regularly,
and if you start using it well before (like 2-4 weeks before) the beginning of
the season for your particular allergens.
Leukotriene esterase is an enzyme involved in allergic inflammation the
nose, throat, and lung. Medicines such as zafirlukast and montelukast
block leukotriene esterase, thus making inflammation less likely to happen.
In this respect they are like cromolyn, but they work very differently. Like
cromolyn, these medicines must be taken regularly to work well.
Mast Cell Stabilizers
Leukotriene Esterase Inhibitors
Immunotherapy (Allergy Shots)
For some patients it is possible to reduce the allergic response to some
allergens by repeatedly injecting low doses of those allergens. This
seems to block the allergic response, although we are not yet quite certain
exactly how the shots work. Allergy shots work best for patients who are
sensitive to airborne allergens (they help people with allergic rhinitis,
and can be helpful to some people with asthma), and can also help reduce
sensitivity to certain stinging insects. The drawback to shots is the
time investment and cost involved (you may need one or two shots per week
at the beginning, although once you have been on them for a while you can
come down to one shot per month), and the risk (small, but not negligible)
of a life-threatening anaphylactic reaction to the extract. When they work,
though, they work quite well -- five years of shots are the main reason why
my allergies are so much better now than before I started taking them.
The mast cells are part of the lining of the air passages; they are part of your immune system, reacting immediately to allergens and other obnoxious stimuli. The mast cells release many different substances when they are stimulated, including histamine.
Cromolyn is a drug that "stabilizes" airway mast cells, making them less prone to releasing histamine and other substances in response to allergens. Because of this, cromolyn sprayed into the nose regularly helps to prevent the nasal inflammation and runny nose of allergic rhinitis. It does not relieve the congestion and drainage immediately. It only helps prevent them -- and it works best if and only if you use it regularly, and if you start using it well before (like 2-4 weeks before) the beginning of the season for your particular allergens.
Leukotriene esterase is an enzyme involved in allergic inflammation the nose, throat, and lung. Medicines such as zafirlukast and montelukast block leukotriene esterase, thus making inflammation less likely to happen. In this respect they are like cromolyn, but they work very differently. Like cromolyn, these medicines must be taken regularly to work well.
You can reduce your allergy symptoms best just by avoiding exposure to the allergens you are sensitive to. Sometimes, though, this is easier said than done.
Allergens in your house are the easiest to avoid, since you have some control over your own environment. Dust mites, for example, live in dust (hence their name) as well as in bedding. If you are allergic to dust mites, consider these measures:
Outdoor allergens are harder to control, of course. You can cut down on some of them in your vicinity, though, especially outdoor molds, by avoiding dead organic material (such as wood chips) in your garden (try crushed stone as a ground cover, instead of wood chips) -- but this may not help much if there are large accumulations of organic material (such as a forest) nearby.