Diagnosis for Food Allergy
When someone has symptoms of a food allergy, it is important to note the time which elapsed between the consumption of the suspected food and the reaction. Food allergy reactions usually occur within minutes, and sometimes, within seconds. So, when a person says that he/she ate a certain food yesterday, some skin itching today is probably not due to a food allergy. Sometimes, a diagnosis can be made via trial and error, by eliminating a suspected food. If the skin clears up, the food is reintroduced to see if the skin flares up once more. If you are attempting such an elimination diet, stay off the offending foods for at least two weeks and add back each food one at a time every three days. {mospagebreak} The best diagnoses, for food allergies, however, are Skin Testing and RAST (blood) testing. In skin testing, the offending food is lightly scratched into the skin by a disposable plastic “Scratcher”. If you are allergic, the area gets red and itchy. The advantages are that the test results are ready within 20 minutes, and that it is cheaper than RAST tests.

RAST testing (which measures the presence of certain allergy–inducing antibodies in your bloodstream) is helpful where there is no specific allergy specialist who does skin testing. RAST testing is also useful as a confirmation of results from skin testing in individuals who have a rash on their back which would complicate a skin test or when only a couple of foods are suspected.

Managing food allergies
It is important to know what to do in case of accidental ingestion, which initially includes an over–the–counter antihistamine, such as diphenhydramine (Benadryl), if the reaction is not severe. In case of a severe attack, one should go to an emergency room. It is recommend that if they have a classic food allergy, they carry information about their allergy. If the allergic foods taste “Funny”, patients may try to leave a suspicious food in their mouth a few seconds before swallowing. The body’s natural desire to eliminate the problematic food by vomiting, can be lifesaving.

Prevention of Food Allergy
Food allergies are most easily developed when we are young. At this stage our intestines are not fully developed and allow large, complex proteins such as peanut protein to cross into the body. Our young bodies recognize such proteins as foreign and form antibodies against them. This may be why there is a great deal of milk allergy and soy allergy when those milks are fed to infants. To prevent peanut allergy, babies ideally should not get peanut protein at all during the first two or three years of life. It is advisable that pregnant women avoid peanuts, especially if there is a family history of food allergies or strong allergic reactions in general. They should also avoid peanut proteins when breast feeding. It may also be helpful to delay the introduction of some other foods (like other nuts, shellfish, milk, wheat, and soy) into an infant’s diet for the first six months of life, but this is a controversial issue. In the future, it is likely that there will be an oral or injected vaccine for peanuts, which will teach the body to become less allergic to it.

Drug Allergies
Some drugs (polymyxin, morphine, X–ray dye, and others) may cause an anaphylactoid reaction (anaphylactic–like reaction) on the first exposure. Anaphylactoid reaction is usually from a toxic or idiosyncratic reaction rather than the “Immune system” mechanism that occurs with “True” anaphylaxis.

Causes of drug allergies
Drug allergies occur when there is an allergic reaction to a medication. This is caused by hypersensitivity of the immune system, leading to a misdirected response against a substance that does not cause a response in most people. The body becomes sensitized (the immune system is triggered) by the first exposure to the medication. The second or subsequent exposure causes an immune response.

Drug reaction manifestations
Reactions to drugs are uncommon, but almost any drug can cause an adverse reaction. Reactions range from irritating or mild side–effects (such as nausea and vomiting), to allergic response including life–threatening anaphylaxis. Some drug reactions are idiosyncratic (unusual effects of the medication). For example, aspirin can cause non–allergic hives (no antibodies formed), or it may trigger asthma. “True” drug allergies involve the production of antibodies and the release of histamine and other chemicals. Most drug allergies cause minor skin rashes and hives. However, other symptoms occasionally develop and life–threatening, acute allergic reactions involving the whole body (anaphylaxis) can occur. Serum sickness is a delayed type of drug allergy that occurs a week or more after exposure to medication or vaccine. Penicillin and related antibiotics are the most common cause of drug allergies. Other common allergy causing drugs include sulfa drugs, barbiturates, anti–convulsants, insulin preparations (particularly animal sources of insulin), local anesthetics such as Novocain, and iodine (found in many X–ray contrast dyes).