A food allergy is an immune system reaction that can happen after eating even a tiny amount of a trigger food. For many, the reaction can lead to anaphylaxis and become life-threatening. A food intolerance is a digestive problem. It’s uncomfortable but not dangerous, and reaction levels often depend on how much of the food you eat. The two can cause some of the same symptoms, which is why many people confuse food allergies with food intolerances. Celiac disease is not a form of food allergy or food intolerance. Rather, it is an autoimmune condition. If you suspect a food allergy, Langford Allergy in Middle Georgia can confirm it with skin testing, blood testing, and oral food challenges.
Key Takeaways for Patients With a Food Allergy or Intolerance
- A food allergy is an immune system reaction; a food intolerance is a digestive system reaction.
- Food allergies can be triggered by trace amounts and can cause life-threatening anaphylaxis. Food intolerances are dose-dependent and not dangerous.
- Allergy symptoms usually appear within minutes to two hours after consumption and can affect the skin, breathing, and digestion. Intolerance symptoms tend to be digestive and appear more gradually.
- Both conditions can cause stomach upset and can involve the same foods, particularly milk and wheat.
- Celiac disease is an autoimmune condition, not an allergy or intolerance, and is managed by a primary care provider or gastroenterologist.
- An allergist can diagnose food allergies accurately using medical history, skin testing, blood testing, and oral food challenges.
- At-home IgG sensitivity tests are not recommended for diagnosing food allergies or intolerances.
Sometimes, Foods Can Become a Threat to Your Health
It’s possible to eat a meal and feel completely off an hour later. Your stomach can start cramping, your skin can start itching, or your breathing can become labored. Whenever it happens, the natural question is: what is going on? You could chalk it up to a bad meal that just didn’t agree with you. Or, it could be signs and symptoms of an allergy or a food intolerance.
“Food intolerance” and “food allergy” are often used interchangeably in everyday conversation, but they are very different conditions. A food intolerance is a frustrating but generally harmless condition that you can usually manage by adjusting your diet. A food allergy, on the other hand, can escalate into a medical emergency within minutes.
Whether it’s either an allergy or an intolerance, it’s important to know which you’re dealing with, identify the triggering ingredient(s), seek the right care, and create a game plan for all future meals.
What Is a Food Allergy?
A food allergy occurs when your immune system mistakenly identifies a protein in a food as a threat. In most food allergy cases, the body produces immunoglobulin E (IgE) antibodies against that protein. Whenever you eat food containing the triggering protein, those IgE antibodies signal immune cells to release histamine and other chemicals, triggering an allergic reaction.
Because the immune system is involved, food allergy reactions can affect multiple parts of the body at once, including the skin, the digestive tract, the respiratory system, and the cardiovascular system.
According to Food Allergy Research & Education (FARE), an estimated 33 million Americans live with food allergies, including roughly one in 13 children. (FARE)
Nine foods account for the majority of allergic reactions in the United States:
- Milk
- Eggs
- Peanuts
- Tree nuts
- Fish
- Shellfish
- Wheat
- Soy
- Sesame
Some food allergies, such as milk and egg allergies, are frequently outgrown in childhood. Others, including peanut, tree nut, fish, and shellfish allergies, are more likely to persist into adulthood. Food allergies can also develop for the first time in adults, which surprises many people.
What Is a Food Intolerance?
A food intolerance, sometimes called a food sensitivity, happens when your digestive system has difficulty breaking down or processing a certain food. The immune system is not driving the reaction; the digestive tract is.
Food intolerances have several common causes:
Enzyme Deficiencies
Lactose intolerance is the best-known example. People with this condition don’t produce enough lactase, the enzyme needed to digest the sugar in milk. The National Institute of Diabetes and Digestive and Kidney Diseases estimates that about 68 percent of the world’s population has some degree of lactose malabsorption.
Sensitivity to Food Additives
Sulfites (found in wine and dried fruit), MSG, and certain artificial colorings can cause symptoms in sensitive individuals.
Poorly Absorbed Carbohydrates
Fermentable carbohydrates known as FODMAPs, found in foods like wheat, onions, garlic, beans, and some fruits, can cause digestive distress, particularly in people with irritable bowel syndrome.
Naturally Occurring Compounds
Some people react to histamine found in aged cheeses, fermented foods, and cured meats, or to caffeine.
Protein Intolerance
Some food intolerances can be attributed to proteins in certain foods that activate a response in the gut, causing inflammation and discomfort. For example, amylase-trypsin inhibitors (ATIs)—proteins found in wheat—can cause reactions whenever a person consumes wheat.
Food Intolerance vs. Food Allergy: The Similarities
It can be hard, especially at first, to differentiate between a food intolerance and a food allergy, because they do share several similarities:
- Both are triggered by specific foods. In each case, symptoms follow eating a particular food or ingredient, and certain foods (milk and wheat, for example) can cause either condition depending on the person.
- Both can cause digestive symptoms. Nausea, stomach pain, vomiting, and diarrhea can occur with either an allergy or an intolerance, making digestive symptoms alone an unreliable way to tell them apart.
- Both usually involve avoiding or limiting the trigger food. Dietary management is central to both, although the level of strictness differs dramatically.
- Both can affect daily life. Eating out, traveling, and social gatherings can become more complicated with either condition.
Milk is a perfect example. A milk allergy is an immune reaction to milk proteins such as casein or whey. Lactose intolerance is a digestive problem with milk sugar. Both involve dairy, and both can cause stomach upset. However, only a milk allergy comes with the risk of anaphylaxis.
Food Intolerance vs. Food Allergy: The Key Differences
While the symptoms can look similar at first glance, several clear distinctions separate the two conditions.
The Body System Involved
A food allergy is an immune system response.
A food intolerance is a digestive system response.
How Much Food It Takes
With a food allergy, even a trace amount of the trigger food, such as a crumb or cross-contact from a shared cooking surface, can cause a reaction.
With a food intolerance, symptoms are typically dose-dependent. Many people with lactose intolerance, for example, can handle a splash of milk in their coffee but not a large bowl of ice cream.
How Quickly Symptoms Appear
IgE-mediated allergic reactions usually begin within minutes and almost always within two hours of eating.
Food intolerance symptoms tend to develop more gradually, often several hours after a meal, as the food moves through the digestive tract.
Food Allergy Symptoms vs. Food Intolerance Symptoms
Food allergy symptoms can include:
- Hives, flushing, or itchy skin
- Swelling of the lips, tongue, face, or throat
- Tingling or itching in the mouth
- Vomiting, stomach pain, or diarrhea
- Wheezing, coughing, or shortness of breath
- Dizziness, lightheadedness, or fainting
Food allergy symptoms can range from mild to severe and can escalate to anaphylactic levels. Call 911 immediately if symptoms appear, and administer epinephrine if there is an autoinjector available.
Food intolerance symptoms are mostly digestive:
- Bloating and gas
- Abdominal cramping
- Diarrhea or nausea
- Heartburn
- Headaches (in some cases)
Food intolerance symptoms can be unpleasant and can affect quality of life. However, they do not cause anaphylaxis and are not life-threatening.
Severity and Risk of Food Allergies and Food Intolerances
A food allergy can cause anaphylaxis, a severe, rapidly progressing reaction that can affect breathing and blood pressure and requires immediate treatment with epinephrine.
A food intolerance, while uncomfortable, does not pose that risk.
What Is Celiac Disease?
Celiac disease is often grouped with food allergies and intolerances, but it is neither of these conditions. Celiac disease is a chronic autoimmune disorder. When a person with celiac disease eats gluten, a protein found in wheat, barley, and rye, their immune system attacks the lining of the small intestine. Over time, this damage can interfere with nutrient absorption and lead to complications such as anemia, bone loss, and fatigue. The Celiac Disease Foundation estimates that celiac disease affects about one in 100 people worldwide.
Celiac disease differs from both conditions discussed above:
Autoimmune Response
- Unlike a food intolerance, celiac disease involves the immune system and causes lasting intestinal damage, even when symptoms are mild or absent.
- Unlike a food allergy, celiac disease does not involve IgE antibodies and does not cause anaphylaxis.
Gluten-Specific
- Someone with a wheat allergy reacts to wheat proteins but may be able to eat barley and rye.
- Someone with a gluten intolerance may actually be reacting to proteins in wheat other than gluten and could possibly tolerate barley and rye, as well.
- Someone with celiac disease must avoid gluten from all sources.
Specialized Testing
- Diagnosis of celiac casease typically involves specialized blood tests followed by an intestinal biopsy, and treatment centers on a strict, lifelong gluten-free diet.
Langford Allergy does not diagnose or treat celiac disease or food intolerances. If you suspect celiac disease or a food intolerance, talk with your primary care provider or a gastroenterologist.
Common Triggers for Food Intolerances and Food Allergies
Some foods are commonly associated with one condition, while others can trigger both.
Foods most often linked to allergies:
- Peanuts
- Tree nuts
- Shellfish
- Fish
- Eggs
- Milk
- Soy
- Wheat
- Sesame
Foods and ingredients most often linked to intolerances:
- Dairy (lactose)
- High-FODMAP foods (wheat, onions, garlic, beans, and certain fruits)
- Sulfites
- MSG
- Caffeine
- Artificial sweeteners
- Histamine-rich foods (aged cheese, wine, and fermented products)
Foods that can cause either:
- Milk
- Wheat
Warning Signs That Point Toward a Food Allergy
Consider seeing an allergist if you notice any of the following after eating:
- Symptoms that appear within minutes to two hours after eating
- Hives, skin swelling, or itching
- Reactions triggered by very small amounts of a food
- Any breathing symptoms, such as wheezing, throat tightness, or coughing
- Symptoms involving more than one body system at the same time, such as hives with vomiting
- A reaction that has become more severe over time
When to Call 911
Call 911 at the first sign of anaphylaxis:
- Difficulty breathing
- Throat swelling
- Hoarse voice
- Trouble swallowing
- Dizziness
- Fainting
- Rapid weak pulse
If an epinephrine auto-injector has been prescribed, use it immediately and call 911.
Warning Signs That Point Toward a Food Intolerance
Digestive discomfort that shows up hours after eating and scales with portion size is more consistent with an intolerance, but it’s still worth discussing with a healthcare provider, especially if symptoms are frequent or disruptive.
How an Allergist Diagnoses a Food Allergy
Many people zero in on triggering foods based on a hunch, only to cut out nutritious foods they could safely eat or miss the real trigger entirely. A board-certified allergist uses a combination of tools to reach an accurate diagnosis.
Detailed Medical History
Diagnosis starts with a conversation about your history with allergies and allergy symptoms. Your allergist will ask what you ate, how much, how quickly symptoms began, what they looked like, and how long they lasted. This detailed history will guide your allergist in choosing the best testing methods for you.
Skin Prick Testing
A small amount of a food extract is placed on the skin, usually on the forearm or back, and the surface is lightly pricked. A raised, itchy bump within about 15 to 20 minutes suggests sensitization to that food.
Blood Testing
A specific IgE blood test measures the level of allergy antibodies to particular foods. Blood testing is useful when skin testing isn’t practical, such as when a patient has widespread eczema or can’t stop taking antihistamines.
A positive skin or blood test on its own doesn’t always mean a true allergy. Some people show sensitization without ever reacting to the food. That’s why results must be interpreted by an allergist alongside your history.
Oral Food Challenges
The oral food challenge is considered the gold standard for diagnosing food allergy. Under close medical supervision in the allergist’s office, the patient eats gradually increasing amounts of the suspected food while the care team monitors for any reaction. Oral food challenges can confirm an allergy, rule one out, or determine whether a child has outgrown a previous allergy, often allowing patients to safely add foods back into their diets.
A Note on At-Home “Sensitivity” Tests
Many direct-to-consumer food sensitivity kits measure IgG antibodies. Major allergy organizations, including the American Academy of Allergy, Asthma & Immunology, do not recommend IgG testing for diagnosing food allergies or intolerances, as IgG antibodies typically reflect normal exposure to foods rather than a true problem. As a result, these tests can lead people to eliminate foods unnecessarily. (AAAAI)
Managing a Food Allergy vs. a Food Intolerance
Managing a food allergy generally involves strict avoidance of the trigger food, careful label reading, awareness of cross-contact, and carrying an epinephrine auto-injector if one is prescribed. Your allergist can also create a written emergency action plan so you, your family, and caregivers know exactly what to do if a reaction occurs.
Managing a food intolerance is usually more flexible. Many people find a tolerable threshold and simply limit portions. Options like lactose-free dairy products or lactase enzyme supplements can help with lactose intolerance, and working with a registered dietitian can help identify triggers such as high-FODMAP foods while keeping your diet balanced.
Frequently Asked Questions About Food Intolerance and Food Allergies
Can a food intolerance turn into a food allergy?
No, a food intolerance can’t turn into a food allergy, or vice versa. Each involves different body systems, so one does not develop into the other. However, it is possible to have both conditions or to develop a new food allergy at any age, so any change in your symptoms is worth discussing with an allergist.
Can you develop a food allergy as an adult?
Yes, you can develop a food allergy as an adult. While many food allergies begin in childhood, adults can develop food allergies for the first time. Shellfish and fish allergies are among the most common adult-onset food allergies.
Is lactose intolerance the same as a milk allergy?
No, lactose intolerance and a milk allergy are two separate conditions. Lactose intolerance is a digestive problem caused by a shortage of the enzyme lactase. A milk allergy is an immune reaction to proteins in milk and can cause hives, vomiting, breathing trouble, or anaphylaxis.
Is gluten intolerance the same as celiac disease?
No, gluten intolerance is not the same as celiac disease. Celiac disease is an autoimmune disorder that damages the small intestine. Non-celiac gluten sensitivity (gluten intolerance) causes symptoms after eating gluten without the autoimmune response or intestinal damage. Both are different from wheat allergy, which is an IgE-mediated food allergy.
How long after eating does a food allergy reaction start?
Most IgE-mediated food allergy reactions begin within minutes and almost always within two hours of eating the trigger food.
What is the most accurate test for a food allergy?
The oral food challenge is considered the gold standard for food allergy testing. It is performed under medical supervision and can confirm or rule out a food allergy when skin or blood test results are unclear.
Should I stop eating a food I think I’m allergic to before testing?
If you’ve had a reaction you believe was allergic, avoid the food until you see an allergist. For suspected celiac disease, however, continue eating gluten until testing is complete, since removing it can affect results.
Get Answers About Your Food Reactions From the Allergists at Langford Allergy: 478-216-1290
Living with uncertainty about what you can safely eat is stressful, whether you’re managing your own symptoms or worrying about a child’s reactions. You don’t have to figure it out through trial and error.
Langford Allergy provides comprehensive food allergy evaluations for children and adults throughout Middle Georgia, including skin prick testing, blood testing, and medically supervised oral food challenges. Our board-certified allergists will help you identify your triggers, understand your risks, and build a plan that keeps you safe while protecting as much variety in your diet as possible.
With offices in Macon, Warner Robins, Milledgeville, and Forsyth, expert allergy care is close to home.
Call 478-216-1290 or send us a message to schedule your consultation.
Langford Allergy is a trusted allergy and immunology practice serving patients throughout Middle Georgia, including, but not limited to, the following cities:
- Byron
- Eatonton
- Forsyth
- Fort Valley
- Gray
- Hawkinsville
- Jeffersonville
- Macon
- Milledgeville
- Perry
- Roberta
- Warner Robins
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