Hello
Yes, we've done this and about to start again on another allergen. DS9, is allergic to nuts, sesame and has various environmental allergies too - wide-ranging hayfever, dustmite, cats, dogs and horses.
He has been seeing Gideon Lack since he was three. In that time, he's been de-sensitised to eggs, which has been a big improvement. He is still allergic, but as long as he regularly eats eggs, he will be able to tolerate them. We are doing the same with pine nuts and coconut.
Four years ago, he started the three year treatment you mention. He had it for hayfevers and tree pollens. It was quite tough at the beginning, so he took it at night. It was tough as it made him tired and he took a while to get used to the idea. My DH also had the treatment. It's been a real success - he was re-tested this week and his reactions were down from an 8 to 2. (Not sure what scale this is measured on, but we all thought it sounded good). He hasn't had one day off school due to hayfever and hasn't had a bad reaction in the last two summers. I think it's great and I had a similar treatment when I was a teen - in those days it was a weekly injection.
We're about to start again, this time with horse and hopefully dust-mite too. It is a long time commitment, but it's a small effort each day and once you get used to it, no different than popping a vitamin or brushing your teeth. We are self paying - it's very expensive, but we think worth it, esp as DS has so many different allergies.
What's your main concern? Is there anything I can help with / info etc?