Allergies affect about 10-20% of the population. This means that up to 1/5 of us suffer from seasonal allergies. Most people without allergies do not appreciate how disabling and crippling allergies can be.
Studies have shown that the majority of allergy sufferers have moderate to severe intermittent or persistent limitations on their quality of life from allergies. It’s nothing to sneeze at!
We have had a pretty cold winter this year in 2013-2014 but for allergy sufferers it’s well known that tree pollen season is just around the corner.
In Ontario, the tree pollen typically starts sometime in March 2014. This is followed by grass allergy season starting in May, June, and July.
So what can patients do to prepare?
Well, it’s not exactly practical to avoid going outside or having your windows closed entirely.
We need for some way to decrease the symptoms or try to “cure” the problem. Pharmacotherapy (medications) and allergen immunotherapy (allergy shots or tablets) have been around for a long time and offer patients a solution to allergies.
Which of the two above do you think has been around longer? It’s actually allergy immunotherapy in the form of injections (shots).
Allergy shots have been around since 1900 when a fellow by the name of Curtis surmised that you can vaccinate against allergies. He took patients with weed allergies and started to inject them with weeds. His patients did improve!
Through a series of experiments and trial and error we have now worked out over the past 104 years exactly how much and how frequently to administer these shots to patients in a controlled and evidence based way. As allergists, we now have practice parameters based on studies that have taken the guess work out of allergy immunotherapy and standardized the practice so that safety and efficacy (effectiveness) are known quantifiable entities.
For tree allergies, currently what exists is a series of injections normally started in January of each year in Ontario. For grass allergies it is started normally in March of each year. One can do tree and grass combined usually starting in January as well. There are several companies in Canada that make these allergen immunotherapy injections.
Allergen immunotherapy works! We can actually measure and see the changes to the immune system including but not limited to how the cells actually talk to one another. By injecting tree pollens in controlled and discrete increasing amounts, your body eventually starts to no longer see the pollen as some parasite over time. This doesn’t work for everyone but meta analysis (large pooled data from multiple well designed trials) show that allergen immunotherapy is of benefit for ~70% of patients.
What is exciting this year is that we now have two forms of grass tablet based immunotherapy. This is essentially grass pollen in a tablet form. The tablet is melted under your tongue where it dissolves and delivers a discrete reproducible controlled amount of grass pollen. This is normally started 8 weeks prior to grass allergy season but it may depend on local climate and weather forecasts.
Neither one of these modalities are “side effect free”. There is a 1 in 2.5 million chance of death to allergy immunotherapy injections and about a 1/1000 chance of experiencing anaphylaxis to either the shots or the tablets. One must wait around 30 minutes after getting each allergy immunotherapy injection and for the tablets the first dose needs to be taken at your allergist’s office and if you are “ok” then you must take the tablets daily at home until the end of grass allergy season which has been historically at the end of July. Most people with the injections just experience local swelling where the injection is done.
The coolest thing about all this is that after about 3 years of the tablets you are able to experience persistent benefit for the grass allergies even if you stop taking the tablets. This effectively is a “cure” or as we like to call it in medicine, disease modification. The same disease modification occurs with allergy injections too, but may take 3-5 years. There is even data that is a 10 year follow up study in children showing that if children receive allergy immunotherapy injections (SCIT) that they are much less likely to develop asthma. The same studies are being now done on tablet based immunotherapy (SLIT) but I suspect the results may be even better.
So why is SLIT potentially better than SCIT? It offers an obvious convenience of home administration however there is something to be said about the mouth being a tolerant organ. Your mouth is exposed to millions of different things everyday from the act of eating. It is trained to recognize what is harmful from you to what is food. It needs to be able to do this or otherwise you’d experience allergic reactions every time you ate something foreign. Unless you’re a cannibal eating your own identical twin, everything is technically foreign to your immune system and mouth. Given that the mouth is an “expert” or special place in your body, it may be the case that it is better at retraining the body for allergies.
Side effects are also possible with SLIT and most people do experience itchiness in the mouth as you are putting something your body is allergic to in the mouth. Keep in mind that multiple safety studies have been done in controlled settings to determine what is the best dose and way of doing this. SLIT has undergone rigorous studies, in fact one could even argue that much more so than drugs like antihistamines or nasal steroids for the treatment of allergies.
Compared to antihistamines and nasal steroids SLIT and SCIT offer superior efficacy for allergies and offers the potential for disease modification. As a physician this is certainly more satisfying that I am shaping the course of a person’s disease in the right direction.
Antihistamines, eye drops, nose sprays of course also help but doesn’t offer the chance of a cure. They are certainly convenient and generally safe however.