It is not likely, at least seems that is not likely to give you an anaphilactic reaction (shock), but since Im not a doctor neither a scientist specialized in the venom peptids and components, I cant answer this any further.
I promise Im not trying to be a jerk but this is a really good question for the forum search function we have discussed it for pages in depth just go to the to pull down the search menu and type in allergic. Ill see if I can pull up what a friend of mine wrote but the search function will serve you best. Thats what im about to use.
So over the past week I've been pondering how much of what we say on the boards is pure knowledge and how much is past down hearsay. I asked my Xgirlfriend who has two BS degrees, in biology and chemistry, to take a look at this board and tell me what she thought about this thread. She did some reading and sent me back this response:
Medical Microbiology 5th edition (Murray, Rosenthal, Pfaller) Elsevier
In spider venom, there are small "proteins" which are called peptides. These peptides bind several receptors on the surface of your cells. This binding signals, among other things, pain. In response to this signal, and the bite itself, your immune system will respond. Worse, however, is that the venom can cause cells to burst, which elicits a huge immune response. When cells burst, they release toxins, which cause nearby cells to also be damaged. This collective damage is what the immune system is actually responding to. One way your immune system fights things that are not bacteria or viruses is by releasing histamine. Histamine is what gives you seasonal allergies. It signals more immune cells to the site, which causes swelling. This is not necessarily how the immune responds to the venom, but rather to the damaged caused by your cells bursting.
In tarantula venom there aren't the peptides that cause the cells to burst, but there are other peptides. But tarantula venom *can* cause an allergic reaction still, just like common food or plant allergies. Symptoms of this would include itching or mild swelling, but since it will be at the site of the bite, it won't be life threatening.
I also read that in some species of tarantula, in addition to these peptides there are "proteases", or enzymes that "chew up" protein. This can include structural proteins, including cartilage, which would cause bruising and tenderness.
More interestingly, there are groups of chemists using the structures common to different kinds of venom to cause the opposite effects: pain killers. They are using the idea of venom, that it binds cell receptors, but then are changing the peptide so that it will not cause the response, pain. But by blocking the receptor without triggering its response, other things that may bind would not be "felt" because the mock-venom would be shielding the receptor.
In short, an immunologist would call both of these responses "allergic", however to the average person on the street, the cell bursting response would be much more identifiable as an allergic reaction.