I think Oxypowder is your best bet and here is why:
If you are allergic to plants, Oxypowder (which is not from plants) will clean out many of the parasites and bacteria in your digestive tract. This may cause you to heal enough to where your allergies are not as much of an issue. My allergies were completely gone after only 2-3 days.
A 7 day cleanse with Oxypowder will almost certainly allow you to tolerate that Para-Buster (or whatever you decide to use for parasites). The oxygen makes your digestive tract a very unfriendly place for parasites and bad bacteria.
I don't believe an herbal cleanse would be good to do if you are allergic to plants.