Nuts provide health benefits, such as protein, unsaturated fats, fiber, vitamins, minerals, and other micronutrients, but they can also have side effects, mostly in the form of allergic reactions. Peanuts rank third among the most common food allergies in young children, and the most common allergic reaction in older children and adults, according to the University of Chicago Pritzker School of Medicine. Nut allergies cause symptoms from the annoying to the life-threatening. Processed foods that contain nuts and foods manufactured in factories where cross-contamination might occur must label their products.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.

Skin Reactions

Skin reactions account for the most common type of food allergy reactions, according to TeensHealth from Nemours 3. Typical skin reactions include rash, facial swelling, especially around the eyes or mouth, hives, itching, a tingling sensation in the mouth or general redness. Fifty-one percent of people with peanut allergy report facial swelling, also called angioedema, according to the University of Chicago; hives affect 47 percent. Some people develop canker sores -- small, painful mouth ulcers -- when they eat walnuts 2.

Respiratory Reactions

Typical allergy reactions that affect the respiratory tract include sneezing, runny nose or coughing. Respiratory allergic reaction to nuts can cause also life-threatening side effects. Swelling in the throat and airways can cause shortness of breath, a tight feeling in the throat or wheezing; these symptoms require immediate medical treatment. The University of Chicago reports throat tightness as the most common side effect in a peanut allergy reported by 53 percent. Shortness of breath occurs in 41 percent and wheezing in 29 percent. Breathing in peanut dust or smelling peanuts usually does not set off an allergic reaction, Nemours states. In small or enclosed spaces, like some restaurants and bars where large amounts of peanut-shell cracking takes place, a rare reaction may occur.

Systemic Reactions

At the average of about 14 months, around 75 percent of children with peanut allergies will develop a severe reaction on their first exposure, according to the University of Chicago. Anaphylaxis causes circulatory collapse, with low blood pressure, heart arrhythmias and loss of consciousness. Death can occur without prompt treatment. People with nut allergies should carry an epi-pen, which contains adrenaline, at all times. Administer at the first sign of significant reaction.

Gastrointestinal Reactions

Abdominal pain or cramping, diarrhea, nausea and vomiting can also occur as part of an allergic reaction to nuts. Vomiting affects 17 percent of people with a peanut allergy and diarrhea occurs in 6 percent, the University of Chicago states.

Diverticular Disease

People with diverticulosis develop small sacs, called diverticula, in the muscle layer of the intestines. Previously prohibited high-risk foods, like nuts and popcorn that might lodge within the sacs, found some vindication in an 18-year Harvard study of 47,228 male health professionals aged 40 to 75 years. As reported in the August 27, 2008 issue of the Journal of the American Medical Association, neither nuts nor popcorn increased the risk of developing diverticulosis or its complications 4. Researchers could not specifically study how nuts and popcorn affected subjects with established, but undiagnosed, diverticulosis. However, because of the higher risk factor for diverticulosis among the middle-aged and elderly study participants, researchers presumed their findings also applied to established, but asymptomatic diverticulosis. If you have diverticular disease, do not make any dietary changes without first consulting your doctor.