While all allergies are annoying and uncomfortable, some can be downright dangerous. In very sensitive individuals, certain allergens--generally foods--cause serious allergic reactions called anaphylaxis. These reactions start with symptoms like swollen lips and tongue, and can progress to difficulty breathing, shock, and eventually death. The body's immune system plays a major role in these severe allergies.
Significance
Unlike food sensitivities, which can cause stomach discomfort and gastric symptoms upon eating an offending food, true food allergies can manifest themselves in a variety of ways, but share the feature of activating the immune system. The body's immune system is its defense against invading pathogens, but it's possible for the body to become confused, explains Dr. Lauralee Sherwood in her book "Human Physiology." In such situations, the body can launch an immune attack against an otherwise harmless substance, leading to disastrous results.
Mechanism
When the immune system overreacts to a harmless substance, antibodies bind to that substance and label it as a foreign invader. Particularly relevant in the case of allergy are the IgE antibodies, which then bind to and activate a class of white blood cells called mast cells, explains Dr. Gary Thibodeau in his book "Anatomy and Physiology." Mast cells respond by releasing histamine, an irritant chemical, which can cause swelling and fluid production by tissues. In the case of very serious allergies, histamine can even cause small blood vessels to become porous and leak fluid. Swollen lips associated with an allergy attack are the result of histamine release.
Considerations
Depending upon the type of allergy, mast cells release histamine in different places in the body. If the allergen is in a food product, histamine release occurs in the tissues of the lips, tongue, and throat. This leads to severe swelling, which is at best uncomfortable, and at worst, can begin to close off the throat and make it impossible to breathe. The Food Allergy and Anaphylaxis Network notes that the foods most commonly associated with severe allergic reaction are shellfish, wheat, eggs, milk, peanuts, tree nuts, fish, and soy.
Prevention/Solution
It's not possible to prevent an allergic reaction that is the result of contact with a food allergen, except by avoiding all contact with that food. Many allergic reactions, once they start, respond to antihistamine drugs like Benadryl, which is a brand name for diphenhydramine. Benadryl helps counteract the effects of histamine and reduces swelling. Note Drs. Mary Campbell and Shawn Farrell in their book "Biochemistry," epinephrine also counteracts many of the effects of histamine, making it an additional option for emergency treatment of severe allergies.
Warning
MedlinePlus, a website maintained by the U.S. National Library of Medicine, warns that any history of allergic reaction--particularly if the reaction included symptoms of mouth or lip swelling--places an individual at risk for severe anaphylaxis. Individuals who have had allergic reactions should contact their physicians to discuss the importance of preventing future reactions, identifying allergens, and carrying treatment medications such as antihistamines and epinephrine. Under no circumstances should an individual who suspects a serious food allergy continue to eat the food in question, since allergies can increase in severity without warning.
References
- "Human Physiology"; Lauralee Sherwood, Ph.D.; 2004
- "Anatomy and Physiology"; Gary Thibodeau, Ph.D.; 2007
- Food Allergy and Anaphylaxis Network: Allergens
- "Biochemistry"; Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
- MedlinePlus: Anaphylaxis
