There is actually no such thing as a gluten allergy. When someone says he is allergic to gluten, he usually means he has gluten intolerance.
A food allergy is a reaction of the immune system to a particular food. When a person's immune system thinks a food is dangerous to the body, it reacts to the food in the form of an allergy. The response symptoms to a food allergen, such as hives, itching, swelling, trouble breathing, abdominal pain, diarrhea, dizziness, nausea, and vomiting, are time-limited and usually don't cause lasting harm, except in the case of an anaphylactic reaction. Food allergies are sometimes temporary, especially in children.
People are not allergic to gluten, which is a protein found in wheat and other grains. Rather, some people's digestive tracts (not their immune systems) have difficulty tolerating gluten and react with gastrointestinal symptoms. Because gluten intolerance is unrelated to the immune system, doctors can't test for it with an antibody test. If you want to know whether you're gluten intolerant, you'll have to try an "open challenge," otherwise known as an elimination diet. Eliminate any foods you suspect might be causing the symptoms. When the symptoms stop, stop eliminating foods and begin slowly reintroducing them one at a time. When the symptoms reappear, you will know what food is causing them.
There is no medicine you can take to treat or cure gluten intolerance. To relieve the symptoms you'll have to follow a gluten-free diet. You may just have gluten sensitivity, which case you may be able to follow a low-gluten diet rather than eliminating gluten altogether. Consult your physician or a dietician to help determine whether you are intolerant of or sensitive to gluten, and what diet you should follow to alleviate your symptoms.