Yes, food allergies can cause acne.

More Info: Interestingly, eight types of food cause 90% of all food allergies in the United States: milk, peanuts, eggs, nuts, fish, shellfish, soy, and wheat.  An allergic reaction to such foods can cause an immediate reaction but may also have long-term effects such as acne, ear infections, eczema, bedwetting, fatigue, headache, irritability, intestinal complaints, fever, hay fever, diarrhea, and chronic runny nose. ["Allergy Facts and Figures." Asthma and Allergy Foundation]

What Are Food Allergies?

Allergic reactions are the human immune system's response to certain proteins. In foods, these can be proteins in nuts, wheat, soy, fruits, chemical additives, or a number of other items. In an allergic reaction, the body reacts negatively to a certain protein, responding as though the protein is attacking the immune system and attempting to protect the body's essential systems. Common symptoms of allergic reactions to food include nausea, wheezing, hives or dermatitis, itching, swelling, and, in very severe cases, respiratory distress or rapid drops in blood pressure and problems with circulation.

How Are Food Allergies Diagnosed?

Food allergies are typically diagnosed by skin tests, elimination diets, or observation. Observation is a risky technique that is carried out under the supervision of a physician because the patient is asked to ingest potential food allergens in the hopes of observing and targeting a reaction. During a skin test, also known as a prick test or scratch test, potential allergens are tested by placing a small amount of the allergen on the skin and scratching the area with a needle to see if a local reaction occurs. Elimination diets can be implemented by completely removing potential allergens from the diet to see if symptoms improve. A physician should also ask about patient history to see if the patient has noted exclusive reactions to certain foods.