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Fill out questionnaire

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Get prescriptions to your pharmacy

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Food Allergy and Intolerance

Food intolerance is a condition where some people experience digestive issues. Issues like cramps, bloating or diarrhea, for example, upon consuming certain foods. There is no allergic reaction in such cases. There are different causes of food intolerance.

Hi! I'm Dr. Jeff Hirschberg
Hi! I’m Dr. Jeff Hirschberg

So you have a Food Allergy, we are sorry to hear that. Let’s schedule a Video-Call so we can get you the medicine you need and discuss causes of food intolerance.

Causes of food intolerance

Although many people use the terms interchangeably, intolerance and allergy are different. There are different causes of food intolerance.

A food allergy is when the immune system of a person reacts abnormally to specific foods. As a result, it triggers a set of responses. Differences between food allergy and food intolerance include the following. For example:

  • Allergic reactions are quick to present themselves. Food intolerance may have a delayed onset of symptoms.
  • Consuming small portions of food that one may be intolerant to does not cause major problems. However, tiny small portions of food that one’s allergic to can cause severe reactions. For example, a person allergic to peanuts will develop instant allergic reactions. This is when they come in close contact with a person who has consumed peanuts. This happens even when one eats food prepared in an area that handles peanuts as an ingredient.

What is an allergy?

Allergic reactions are the body’s way of responding to external substances. These substances are an allergen. While allergens may not be harmful by themselves, they may trigger a reaction in some people. They could vary in severity from person to person and may exhibit different symptoms as well. The life-threatening reaction is anaphylaxis.

What is a food allergy?

A food allergy is the abnormal reaction of the body’s immune system to a particular food. It usually presents a host of side effects. While there is no conclusive data, more people assume they are allergic to a particular food. However, it may not be true upon testing. Children with food allergies usually outgrow the condition when they are older. For example, those that are allergic to cow’s milk. It is true that more people report food allergies every year, but their severity varies.

Depending on which part of the immune system responds to it, food allergies can be of different types. For instance:

  • Antibodies immunoglobulin E (IgE) tends to cause acute and sudden-onset reactions. Histamine is produced and antihistamines treat this type of reaction.
  • Non-IgE-mediated reactions usually show a delayed onset of symptoms. These reactions are also less severe as well. A type of white blood cell called T cells cause this type of reaction.
  • Some common reactions are abdominal pain, bowel problems, rashes or eczema. You may even have a combination of them.

Symptoms and causes of food intolerance

Food intolerance is a condition where some people experience digestive issues. Issues such as cramps, bloating or diarrhea upon consuming certain foods. There are different causes of food intolerance. There is no allergic reaction in such cases.

Irritable Bowel Syndrome or IBS may also cause similar symptoms as food intolerance as well. Symptoms such as bloating and diarrhea, for example. Certain food additives like MSG or monosodium glutamate directly affect the body. They may result in headaches, bloating, abdominal pains or flushing. It is sometimes unclear what triggers the symptoms and the cause of food intolerance.

Lactose intolerance

One common cause of food intolerance is lactose. Lactose intolerance is a disorder of the digestive system. It is where a person is unable to digest lactose. Lactose is the main carbohydrate in dairy products and milk. People with lactose intolerance are unable to secrete the enzyme lactase. This enzyme is necessary to digest lactose. This is what causes the food intolerance. Symptoms of lactose intolerance include bloating and abdominal pain. Diarrhea is also a symptom as well. The trigger is the consumption of milk or dairy products.

Food avoidance as a remedy

Vomiting and diarrhea may happen when people eat food they dislike. While this may not be intolerance to the food per se, it makes it difficult to classify what brings on the symptoms. One may end up excluding foods that are important. Even though they do not trigger any allergic reactions. Especially in young children, such practices may affect their growth or develop malnutrition. They avoid the food because they think its the cause of their food intolerance.

Mouth and throat (oral) allergy syndrome

Fresh fruit, certain vegetables, and nuts can cause an allergic reaction. It is confined to the mouth and throat area in some people. Common reactions are, for example, swelling of the tongue and lips. Additionally, sudden obstruction of the airway is another common reaction as well. Some people confuse this with anaphylaxis.

Eating certain foods in their raw form may trigger swelling of the tongue and throat. But it is usually safe for the person to consume the same foods after cooking. This is because it destroys the allergy-inducing proteins in the process. The symptoms appear quickly and settle down or reduce significantly within an hour. People who get hay fever are likely to suffer from oral allergy syndrome as well. Seek medical help immediately if you feel like you are unable to breathe. Additionally, seek medical help if you feel faint or feel like your throat is constricting.

How it Works

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Symptoms of food allergy

Some of the symptoms when a food allergy is due to an IgE allergic reaction include, for instance:

  • Itchy watery eyes
  • Nausea or vomiting
  • Feeling breathless, wheezing
  • Tingling in the mouth
  • Swelling of the lips, tongue or throat
  • Itchy skin or rashes, feeling flushed
  • Abdominal pain
  • Diarrhea
  • Runny nose, Sneezing
  • Feeling dizzy and light-headed
  • Swelling around the eyes

The onset is quick and immediate upon consumption of the trigger food.

Some of the symptoms when a food allergy is caused due to non-IgE allergic reaction include symptoms such as:

  • Persons with hay fever/asthma may get atopic eczema
  • Gastroesophageal reflux or effortless vomiting
  • Diarrhea or constipation
  • Mucus or blood-stained stool
  • Redness around the anus
  • Being pale or feeling tired
  • Poor growth (especially in children)

Which foods cause most allergies?

Foods that commonly cause allergies are, for instance:

  • Milk
  • Nuts (mainly peanuts)
  • Eggs
  • Shellfish
  • Seafood
  • Sesame
  • Citrus fruits
  • Kiwi
  • Soy
  • Wheat


If you suspect you or your child may have a food allergy, bring it up with your doctor. A referral to a specialist or for testing to confirm a diagnosis may be necessary in some cases. Cases such as:

  • A severe allergic reaction occurred
  • If a child is not growing well
  • It there are gastrointestinal symptoms

If you suspect you may have food intolerance, and the symptoms are mild, you may want to try and find out the trigger food on your own. This is based on observance. In severe cases, seek medical help immediately.

Food diary

Write everything you eat during the day. Additionally, write any reactions it may trigger. While this method may not be conclusive, it can shed light on some problematic foods. It can also show how they affect you and causes of food intolerance as well.

Specific tests

There are skin prick and blood tests that may be done if one suspects to have an IgE-mediated allergy.

How skin prick tests work

The skin prick test is performed by a specialist in a hospital setting. There is access to resuscitation equipment and epinephrine injections are readily available.

  1. A solution is prepared by mixing the allergens with a liquid.
  2. One drop of this liquid is placed on the hand of the person and a needle is pricked gently under the drop. This causes a small amount of the allergen to enter the bloodstream.
  3. The skin is checked for any allergic reaction.
  4. If the skin becomes red and itchy or causes to erupt in wheals, the reaction is positive. This should go away in a few hours.

Blood tests

Blood tests can be very expensive and also nonconclusive. The test may be able to detect if specific IgE antibodies are present in your blood. IgE antibodies like those for peanuts as an example.

The advantage of blood tests is that they are safe in people who have anaphylaxis. Additionally, it is recommended for those with severe skin diseases as well. The main drawback of this method is that they work well for testing only a limited number of allergens.

Elimination and challenge

A food that is suspected of triggering the reaction is eliminated from the diet for 2-6 weeks. Check if the symptoms have reduced drastically. Reintroduce the suspected food to the diet. Then check if the symptoms return to determine the cause of food intolerance.

Talk to your physician before attempting the elimination method. Also, continue eating a balanced diet as well.

Placebo-controlled food challenge tests are expensive and difficult to execute. Therefore, it is not widely recommended. This requires several days of monitoring and one is also required to drink a solution. Every dosage contains more of the allergic food than the previous dose. It is randomly replaced with nonallergic food over the course of a few days. The test must be done in a facility where emergencies can be treated should the reaction quickly escalate.

Treatment for food allergies

  • Antihistamines are a class of drugs that suppresses any untoward allergic reaction.
  • Avoid allergy-inducing foods.
  • If you have a severe allergy, always carry an epinephrine injection with you.
  • A medical bracelet citing all the allergies can be worn on the wrist for emergency situations.

Referral to a dietician

Dieticians are able to diagnose and treat dietary problems. They are qualified health professionals. Nutritionists and therapists, however, register voluntarily. They also largely base their treatments on personal beliefs and opinions.

Once the specialist provides a recommendation to avoid a particular food due to an allergy, a dietician helps you in continuing to eat a balanced diet. This is especially true for children as it can seriously affect their growth and development.

Outlook (prognosis)

Most allergies tend to become better or manageable after a few years. This is based on avoidance and the immunity system getting more mature. Young persons with an allergy to milk, eggs, soy, wheat, etc typically outgrow the condition as they get older. Only people with allergic reactions to certain foods like fish, seafood, and peanuts rarely see improvement in their condition.

Celiac disease

Autoimmune diseases are not a food allergy or intolerance outcomes. They are conditions where the immune system attacks itself mistakenly rather than foreign substances. One commonly occurring disease in the US is Celiac disease. It is often caused by a sensitivity to gluten in products. Products such as pasta and bread, for instance. It can result in bloating or cramps till the food particle is removed from the body.

Peanut allergy, pregnancy, breastfeeding and weaning

Owing to the lack of conclusive research findings, pregnant or breastfeeding women do not need to avoid eating peanuts. This is as long as they are not allergic to the peanuts themselves.

The World Health Organization (WHO) advises that:

  • Babies be exclusively breastfed for the first six months.
  • If weaning on to solid food happens before 6 months of age, avoid peanuts and nut-containing foods.
  • Also avoid foods with seeds, cow’s milk, eggs, wheat, fish and shellfish.
  • When a child is no longer breastfeeding, it is best to introduce one new food at a time. This helps is zeroing in on an allergy-inducing food easily.




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