Food Allergy – Symptoms and Causes
Overview
Food allergies trigger immune system reactions when certain foods are eaten. Even small amounts of these foods can cause symptoms like hives, breathing problems, and digestive issues. In severe cases, food allergies can lead to anaphylaxis, a potentially life-threatening reaction.
About 8% of children under 5 and up to 4% of adults have food allergies. While there’s no cure, some children do outgrow their allergies as they get older.
It’s important to distinguish between food allergies and food intolerances. Though they may seem similar, food intolerances:
- Don’t involve the immune system
- Are more common
- Are typically less serious
Food intolerances can cause discomfort but don’t pose the same risks as true allergies. Understanding this difference helps with proper diagnosis and management.
Signs and Effects
Food allergies can cause different reactions in people. Some may feel only mild discomfort, while others might face serious, life-threatening situations.
Most symptoms show up within minutes to two hours of eating the problem food. In rare cases, reactions might happen several hours later.
Common food allergy signs include:
- Mouth itching or tingling
- Skin reactions (hives, itching, eczema)
- Swelling in the lips, face, tongue, throat, or other body parts
- Stomach issues (pain, diarrhea, nausea, vomiting)
- Breathing problems (wheezing, stuffy nose)
- Feeling dizzy, lightheaded, or fainting
Severe Allergic Response
Some people may have a dangerous reaction called anaphylaxis. This serious condition can include:
- Airways becoming narrow and tight
- Swollen throat or feeling of a lump making breathing difficult
- Dramatic drop in blood pressure (shock)
- Fast heartbeat
- Dizziness, lightheadedness, or passing out
Important: Anaphylaxis requires immediate emergency treatment. Without proper care, it can be deadly.
When Medical Help Is Needed
Visit a doctor or allergy specialist if you notice food allergy symptoms soon after eating. Getting checked while having a reaction can help doctors make the right diagnosis.
Seek emergency care immediately if you experience any of these severe symptoms:
- Trouble breathing due to airway tightness
- Severe blood pressure drop causing shock
- Racing pulse
- Feeling very dizzy or lightheaded
What Causes Food Allergies
Food allergies happen when your immune system mistakes a food for something harmful. Your body creates antibodies called immunoglobulin E (IgE) against specific food proteins.
When you eat that food again, these antibodies trigger chemicals like histamine to be released, causing allergy symptoms.
Most food allergies come from eight main foods:
- Shellfish (shrimp, lobster, crab)
- Peanuts
- Tree nuts (walnuts, pecans)
- Fish
- Eggs
- Milk
- Wheat
- Soy
Pollen-Food Reaction Syndrome
Pollen-food reaction syndrome affects many people with hay fever. When eating certain fresh fruits, vegetables, or nuts, your mouth may tingle or itch. This happens because proteins in these foods are similar to pollen proteins.
Cooking these foods often reduces symptoms. The reaction is usually worse with raw foods.
| If You’re Allergic To This Pollen | You might react to these foods |
|---|---|
| Birch | Apples, cherries, peaches, plums, almonds, hazelnuts, carrots, celery, pears, soybeans |
| Ragweed | Bananas, cucumbers, melons, zucchini |
| Grasses | Kiwi, melons, oranges, tomatoes, peanuts, potatoes |
| Mugwort | Apples, bell peppers, broccoli, cabbage, garlic, onion, carrots, celery |
In severe cases, this condition can cause throat swelling or serious allergic reactions.
Exercise-Triggered Food Allergies
Some people experience itching, lightheadedness, or even hives after eating certain foods and then exercising. In rare cases, this combination can cause severe allergic reactions.
To prevent problems:
- Don’t eat for 2 hours before exercise
- Avoid trigger foods before physical activity
Food Intolerance and Similar Reactions
Food intolerance can cause symptoms that seem like allergies: nausea, vomiting, stomach pain, and diarrhea.
The key difference is that with intolerance, you might handle small amounts of the food without problems. With true allergies, even tiny amounts can trigger reactions.
Several conditions are often confused with food allergies:
Enzyme Deficiencies: Your body might lack enzymes needed to digest certain foods. For example, without enough lactase enzyme, you can’t properly digest milk sugar (lactose), causing gas, bloating, and diarrhea.
Food Poisoning: Sometimes bacteria in food create symptoms that look like allergic reactions.
Additive Sensitivity: Some people react to food additives like sulfites, which are used in dried fruits, canned goods, and wine.
Histamine Toxicity: Improperly stored fish like tuna can develop high histamine levels, causing allergy-like symptoms. This is actually histamine poisoning, not an allergy.
Celiac Disease: This immune response to gluten damages the small intestine. When someone with celiac eats foods with wheat, barley, or rye, their body attacks their intestinal lining, preventing proper nutrient absorption.
Food reactions can be complex. Some people react not to the food itself but to ingredients used in preparing it.
Risk Factors
Several factors can increase your chances of developing food allergies:
Family History and Genetics
- If your family has asthma, eczema, hives, or other allergies like hay fever, you face a higher risk of food allergies.
- This genetic connection plays a significant role in how your immune system responds to certain foods.
Existing Allergic Conditions
- Having one food allergy increases your risk for developing others.
- People with hay fever, eczema, or other allergic reactions are more likely to develop food allergies.
Age Factors
- Children, especially infants and toddlers, experience food allergies more frequently.
- As children grow, their digestive systems develop, often allowing them to overcome allergies to milk, eggs, wheat, and soy.
- Nut and shellfish allergies typically persist throughout life.
Asthma Connection
- Asthma frequently occurs alongside food allergies.
- When both conditions exist together, symptoms of each tend to be more severe.
Anaphylaxis Risk Factors
| Risk Factor | Description |
|---|---|
| Age | Teenagers and younger children face a higher risk |
| Asthma | Having an asthma history increases severity |
| Treatment delay | Postponing epinephrine use when symptoms appear |
| Skin symptoms | Lack of visible symptoms like hives can mask severity |
Complications
Food allergies can lead to serious health issues. Severe allergic reactions, called anaphylaxis, may occur, which can be life-threatening without prompt treatment.
Some people also develop skin problems. Food allergies may trigger eczema (atopic dermatitis), causing red, itchy, and inflamed skin patches.
Ways to Prevent Food Allergies
Starting Foods Early
Research shows that giving peanut products to babies early may lower their chances of developing allergies.
A key study found that high-risk infants who ate peanut foods regularly between 4-6 months and 5 years of age were about 80% less likely to develop peanut allergies compared to those who avoided them.
Before adding new foods that might cause allergies to your baby’s diet, speak with a doctor. They can help you decide the right time to introduce these foods based on your child’s health history.
Staying Safe with Food Allergies
If you already have food allergies, avoiding trigger foods is the best way to prevent reactions. This can be simple for some people but challenging for others. Especially when eating out or at social events where ingredients may be hidden.
Steps to protect yourself:
- Read labels carefully – Always check ingredient lists on food packages.
- Wear medical ID – If you’ve had severe reactions, wear a bracelet or necklace that identifies your allergy.
- Carry emergency medicine – Ask your doctor about carrying an epinephrine autoinjector like EpiPen if you’re at risk for severe reactions.
- Be clear at restaurants – Tell servers and chefs about your allergy and make sure they understand the seriousness.
When dining out, don’t hesitate to ask questions about how food is prepared. Restaurant staff usually want to help keep you safe when they understand your needs.
Planning ahead helps too:
- Pack safe snacks when traveling
- Bring allergen-free treats to parties so you don’t feel left out
For parents of children with food allergies:
| Action | Details |
|---|---|
| Inform caregivers | Tell teachers, childcare providers, and other adults about your child’s allergy |
| Teach symptoms | Help adults recognize what an allergic reaction looks like |
| Create an action plan | Write down steps to take during a reaction and share them with school nurses and caregivers |
| Use a medical ID | Have your child wear a medical alert bracelet that explains their condition |
Tips for schools and childcare:
- Make sure all staff know which children have allergies
- Train everyone to recognize reaction symptoms
- Know how to use emergency medication
- Have clear procedures for food-related activities
For those with severe allergies, having emergency medication available at all times is essential. Teaching friends and family how to help during a reaction provides an extra layer of protection.
