What do you call an antigen that causes an allergic reaction?
491694
i dont know the name but a few of them are histamine and adrenaline
274963
Hives are usually an allergic reaction to food or medicine.\nWhen you have an allergic reaction to a substance, histamine and other chemicals are released into your bloodstream, causing itching, swelling, and other symptoms. Hives are a common reaction, especially in people with other allergies like hay fever.\n\nWhen swelling or welts occur around the face, especially the lips and eyes, it is called angioedema. Swelling from angioedema can also occur around your hands, feet, and throat.\n\nMany substances can trigger hives:\n\nMedications \nShellfish, fish, nuts, eggs, milk, and other foods \nPollen \nAnimal dander (especially cats) \nInsect bites \nHives may also develop from:\n\nInfections like mononucleosis or illness (including lupus, other autoimmune diseases, and leukemia) \nEmotional stress \nExtreme cold or sun exposure \nExcessive perspiration \n\n\nBtw, I also had hives before and after several tests, it turned out to be a physical reaction to high stress and nervousness
916443
Heat rash or some sort of allergy...:
241539
You could be allergic to that kinda of vitamin
1079825
There is a OTC medicine called Drixoral. It works really well, as well as Benadryl, or generic Diphenhydramine. If none of those work, you may want to make an appearance at the office of a holistic doctor-he/she will do an allergy test and you may be able to have your reaction to allergens desensitized.
1012909
Lidocaine?  Any drug may cause an allergy.
719379
if you are allergic to only the egg white you are most likely allergic to the protein that is in it. the main protein that makes up an egg white is ovalburnin. different people are allergic to different things so you're just made that way. so be careful with what you eat!
650599
Cell-Mediated Immunity\nIndex to this page \nDelayed-Type Hypersensitivity (DTH) \nContact Sensitivity \nKilling intracellular parasites \nAnti-Viral Immunity \nGraft Rejection \nGraft-versus-host disease \n \nThe human body can respond to antigen in many different ways. These fall into two major categories: \nantibody-mediated immunity. Antibodies, dissolved in blood, lymph, and other body fluids bind the antigen and trigger a response to it. (This form of immunity is also called humoral immunity.) Discussion of antibodies \n\ncell-mediated immunity (CMI). T cells (lymphocytes) bind to the surface of other cells that display the antigen and trigger a response. The response may involve\nother lymphocytes and \nany of the other white blood cells (leukocytes)
318994
Are you referring to the shock of say, a bee sting?  An anaphylactic shock occurs when the person afflicted has a very specific allergy to what they've been exposed to.  Poison ivy is one of those things that most people have a mild allergy to and it's dematological in nature . . . so it affects mainly your skin and the areas directly affected.  \n\nEven an anaphylactic shock can take up to 4 hours to set in.
353921
The short answer: HISTAMINE.\n\nThe long explanation in the simplest terms I can explain it in: \nWhether as a reaction to the enzymes from the bug's saliva, or from the damaged done from the act of biting, your body sends in the cavalry - mast cells - to the rescue. Mast cells are an important part of the immune system, and whenever there is damage in your body (injury such as a wound, insect bite, etc., or inflammation) OR an invader (allergen, virus, bacteria), the immune system sends mast cells, basophils, and other immune cells to the site of the problem. Mast cells contain several different chemicals, including histamine, which they release through a process called degranulation. Histamine is actually what is causing the itch of the bug bite. It's the same chemical which causes hives and other symptoms of allergy. It's also the reason why a wound often itches as it heals.
1077981
what is it allergic to?
438590
Because you have allergies.
1118935
I had something similar - it turned out to be an allergic reaction.  Ultimately though, this could be many things.  I definitely recommend going to the doctor.
167933
rabies\nYou can be allergic to them.
655371
I think that the correct word you are looking for is IMMUNOGEN: "any substance or organism that provokes an immune response (produces immunity) when introduced into the body"\n\nNot all immunogens are antigens (which means "substance capable of raising antibodies against it") nor allergens ("responsible of causing allergy, a particular kind of immune response.")
675044
Normally, the body learns to defend itself through experience - by encountering, battling and remembering one enemy after another. For decades, medical science has taken advantage of this ability by using vaccination to create immunity - the immunologic "memory" of a disease. Allergic reactions occur after the immune system mistakenly learns to recognize innocent foreign substances (allergens) as potentially harmful.\n\nThe following story illustrates how an allergy can develop:\n\nOver a field of ragweed plants floats an invisible cloud of pollen grains, soon carried by the wind into a nearby town. The pollen is inhaled by a child whose body has never been exposed to this substance before.\n\nBecause of some genetic predisposing factor, this child's immune system overreacts and produces large numbers of IgE antibodies, all specially designed to respond to ragweed pollen. Several of the antibodies attach themselves to cells in the child's nasal passages and upper respiratory tract.\n\nThese cells (known as mast cells) contain strong chemicals called mediators, the best-known of which is histamine.\n\nLater, when the child inhales the same kind of pollen again, proteins from the pollen bind in a lock-and-key fashion to the specially designed antibodies on the surface of the mast cells. This sets off an explosion of sorts, as the mediators burst from inside the mast cells, destroying the pollen and also damaging surrounding tissues. The results are sneezing, a stuffy head, sniffling, stuffed-up head and red, watery eyes - well-known hallmarks of allergies.
1084287
Anaphylaxis is a severe allergic reaction due to a Type I Hypersensitivity reaction.  In this type of reaction, exposure to an allergen triggers mast cells to release large amounts of histamine.  This can cause shock and suffocation due to the closure of the airway, among other symptoms.  Diphenhydramine (Benedryl) can be used to treat anaphylactic shock.  Oral diphenhydramine is usually not fast-acting enough, so an injection is given.  Epinephrine can also be injected to counteract the affects of shock, maintaining blood flow to the body and opening the airways (via Beta-2 adrenergic stimulation to the airways).