Peanuts are among the most common allergy-causing foods, and they often find their way into things you wouldn't imagine. Take chili, for example: It may be thickened with ground peanuts.
Peanuts aren't actually a true nut; they're a legume (in the same family as peas and lentils). But the proteins in peanuts are similar in structure to those in tree nuts. For this reason, people who are allergic to peanuts can also be allergic to tree nuts, such as almonds, Brazil nuts, walnuts, hazelnuts, macadamia nuts, pistachios, pecans, and cashews.
What Happens With a Nut or Peanut Allergy?
The body's immune system normally fights infection. But, when someone is allergic to tree nuts or peanuts, the immune system overreacts to proteins in these foods. Every time the person eats (or, in some cases, handles) a peanut or tree nut, the body thinks the proteins are harmful invaders. The immune system responds by kicking into high gear to fend off the "invader." This causes an allergic reaction, in which chemicals like histamine are released in the body.
The release of these chemicals can cause someone to have some or all of the following problems:
- wheezing
- trouble breathing
- coughing
- hoarseness
- throat tightness
- stomachache
- vomiting
- diarrhea
- itchy, watery, or swollen eyes
- hives
- red spots
- swelling
- a drop in blood pressure
Reactions to foods, like peanuts and tree nuts, can be different. It all depends on the person — and sometimes the same person can react differently at different times.
Nut and peanut allergies can cause a severe reaction called anaphylaxis. Anaphylaxis may begin with some of the same symptoms as a less severe reaction, but then quickly worsen, leading someone to have trouble breathing, feel lightheaded, or to pass out. If it is not treated quickly, anaphylaxis can be life threatening.
Although a small amount of peanut protein can set off a severe reaction, it is rare that people get an allergic reaction just from breathing in small particles of nuts or peanuts, since the protein has to be ingested (swallowed) to cause a reaction. Most foods with peanuts in them don't allow enough of the protein to escape into the air to cause a reaction. And just the smell of foods containing peanuts won't produce a reaction because the scent does not contain the protein.
In very rare cases when people do react to airborne particles, it's usually in an enclosed area (like a restaurant or bar) where lots of peanuts are being cracked from their shells. The person inhales and then swallows the protein, and this can lead to a reaction when the protein gets digested.
Although some people outgrow certain food allergies over time (like milk, egg, soy, and wheat allergies), peanut and tree nut allergies are lifelong in many people.