In a food allergy, your body’s defense system, called the immune system, reacts to a certain food or ingredient as if it were harmful.

The foods that most often cause allergic reactions in adults are the same for women and men. They include:

• Shellfish, such as shrimp, crayfish, lobster, and crab
• Peanuts
• Tree nuts, such as walnuts, cashews, and pecans
• Fish, such as salmon
• Milk
• Eggs
• Wheat
• Soybeans

The symptoms of an allergic reaction to a food usually develop within a few minutes to an hour after you eat the food. You may first feel itching in your mouth as you start to eat the food.

Other symptoms include:

• Stuffy, itchy nose
• Sneezing
• Itchy, watery eyes
• Swelling of the lips, face, tongue, throat, or other parts of your body
• Vomiting
• Diarrhea
• Stomach cramps
• Red, itchy skin or a rash

If you have food allergy symptoms shortly after eating, see your doctor or nurse. If possible, see your doctor while the allergic reaction is happening.

They can be. For some people, an allergic reaction to a food is uncomfortable but not serious. But for others, an allergic food reaction can lead to death. A life-threatening reaction caused by an allergy is called anaphylaxis.

For these people, even the smallest amount of exposure — eating a food or even touching someone who is eating the food — can be dangerous. If you have anaphylactic reactions to certain foods, your doctor may give you a prescription for injectable epinephrine. You need to carry this medicine with you at all times so that you or someone you are with can give you an emergency injection if needed.

Symptoms of anaphylaxis include:

• Hoarseness, throat tightness, or a lump in your throat
• Wheezing, chest tightness, or trouble breathing
• Rapid heart rate
• Dizziness, lightheadedness, or fainting
• Tingling in the hands, feet, lips, or scalp
• Cold, clammy, grayish, or bluish skin

Anaphylaxis is a medical emergency. If you or someone you know has any of these symptoms after eating something, call 911 right away.

Yes, other health problems can have some of the same symptoms as a food allergy. This can make it hard to know for sure whether you have a food allergy.

These health problems include:

• Food poisoning from contaminated food or foods with poisons, such as certain mushrooms
• Lactose intolerance
• Irritable bowel syndrome 
• Reactions to large amounts of some food additives, such as monosodium glutamate (MSG, a flavor enhancer)

You do not need to avoid foods such as peanuts, milk, or eggs during pregnancy — unless you are allergic to any of these foods.

According to the American Academy of Pediatrics:^3,4

• Avoiding certain foods in pregnancy does not prevent food allergies in children
• Breastfeeding may prevent or delay food allergies
• Soy-based infant formula does not appear to prevent food allergy
• Delaying the introduction of solid foods beyond 4 to 6 months of age does not prevent food allergies. Some people have also thought that food allergies might be prevented if parents delayed giving their babies certain solid foods (such as fish, eggs, and milk). But current medical research does not support this idea.
• Recent research has shown that eating foods containing peanuts early in life may prevent a peanut allergy. If your infant has severe eczema, an egg allergy, or both, you may be able to give peanut-containing foods as early as 4 to 6 months of age to help prevent a peanut allergy.⁵ Check with your doctor or nurse before feeding your infant foods containing peanuts.

No. But sometimes babies may be allergic to something their mother eats, such as eggs, milk, or cheese. Babies who are highly sensitive usually react to the food within minutes. Babies who are less sensitive may still react to the food within four to 24 hours.

Symptoms may include:

• Diarrhea, vomiting, and/or green stools with mucus and/or blood
• Rash, eczema, dermatitis, hives, or dry skin
• Fussiness during and/or after feedings
• Inconsolable crying for long periods
• Sudden waking with discomfort
• Wheezing or coughing

These symptoms do not mean your baby is allergic to your milk, but rather to something you are eating. Talk with your baby’s doctor about any symptoms. If your baby ever has problems breathing, call 911 or go to your nearest emergency room.

Learn more in our Breastfeeding and Everyday Life section.

For more information about food allergies, call the OWH Helpline at 1-800-994-9662 or check out the following resources from other organizations:

• Facts and Statistics — Information from the Food Allergy Research and Education.
• Food Allergies: What You Need to Know — Information from the Food and Drug Administration.
• Food Allergy — Information from the National Institute of Allergy and Infectious Disease.

1. National Academies of Sciences, Engineering, and Medicine. (2017). Finding a path to safety in food allergy: Assessment of the global burden, causes, prevention, management, and public policy. Washington, DC: The National Academies Press. doi: 10.17226/23658.
2. Centers for Disease Control and Prevention. (2013). Trends in Allergic Conditions Among Children: United States, 1997-2011.
3. Luccioli, S., Zhang, Y., Verrill, L., Ramos-Valle, M., Kwegyir-Afful, E. (2014). Infant Feeding Practices and Reported Food Allergies at 6 Years of Age. Pediatrics; 134(Suppl 1): S21-S28.
4. National Institute of Allergy and Infectious Diseases. (2011). Guidelines for the Diagnosis and Management of Food Allergy in the United States: Summary for Patients, Families, and Caregivers. 
5. National Institute of Allergy and Infectious Disease. (2017). Addendum Guidelines for the Prevention of Peanut Allergy in the United States: Summary for Parents and Caregivers.