Soy Allergy

By | June 10, 2022

More and more people are opting for products containing soy. But not everyone can tolerate the legume; a soy allergy is not uncommon these days, and in many cases it is a cross-allergy. This means that the allergic person also reacts to other legumes.

What is a soy allergy?

If allergy symptoms occur after eating soy or products containing soy, the doctor speaks of a soy allergy. In many cases, a soy allergy represents a cross-allergy; This means that overreactions also occur when the allergic person also eats other legumes – such as peanuts or peas. For this reason, doctors also speak of a cross allergy. For idiopathic pulmonary fibrosis explanations, please visit


In principle, there are two ways why a soy allergy can occur, so that the doctor has to distinguish between a secondary and a primary soy allergy: if it is a primary allergy, the allergic person is allergic to soy; if there is a secondary allergy, there is a pollen-associated allergy.

Those affected therefore react allergically to the pollen of a hazelnut, an alder or even a birch. Since soy contains a similar protein, the body can also react to it, so that the body’s immune defense cells are activated. In this form, there is no classic soy allergy.

Symptoms, Ailments & Signs

Those affected complain of a tingling lip, a tingling oral mucosa or a tingling tongue, which can subsequently lead to numbness, swollen oral mucosa, itching and shortness of breath.

The symptoms are varied – there are therefore no typical or classic symptoms that subsequently suggest a soy allergy. Many of those affected suffer – after just a few minutes – from oral allergy syndrome. This means that the tongue, lips and oral mucosa tingle or sometimes go numb. In many cases, the mucous membranes can also swell, so that the person affected suffers from shortness of breath.

Anaphylactic shock can then occur, sometimes causing cardiac arrest. There is therefore an acute danger to life! Allergic reactions can also show up on the hand.

Those affected suffer from redness or itching, which can also lead to widespread hives. If the person concerned is already suffering from neurodermatitis, the symptoms can be even more severe. Sometimes those affected also complain of nausea, vomiting or severe diarrhea.

Diagnosis & course of disease

The primary allergy can be determined relatively easily. Here the doctor uses the results of the skin prick test. The doctor divides the forearm into different sections, which he marks with numbers and then tests different allergens. So if there is a soy allergy, allergic reactions develop – only in the treated area – if the solution mixes with the blood.

Blood tests are another way of diagnosing a soy allergy. The doctor takes the specific IgE antibodies that the body has already formed against soy. However, it becomes more problematic if there is a secondary soy allergy. The secondary allergy is possible if the affected person is already allergic to alder, birch or hazelnut.

The allergy sufferer must first carry out a special elimination diet, during which he is subsequently confronted with a large number of various allergens; if there are allergic reactions – triggered by soy – it is clear that there is a secondary soy allergy. It can sometimes take weeks for the doctor to come to a conclusion.


The complications that have to be expected with a soy allergy are not fundamentally different from those of other food intolerances. Symptoms of a soy allergy are usually mild to moderate. After consuming foods containing soy, those affected complain of symptoms such as tingling lips, swollen oral mucosa or itchy tongue and throat problems, especially pain when swallowing.

Occasionally there is also slight shortness of breath. If the course is severe, there may be other side effects. Some patients then develop allergic reactions on their hands. Patients often suffer from reddening of the skin and severe itching, and in rare cases there is widespread hives.

The most serious complication to be expected is anaphylactic shock, which can result in cardiac arrest. In this case, there is an acute danger to life for the patient. Further complications can arise during minor surgical interventions.

For sedation in endoscopy, for example, the active ingredient propofol is very often used, which can cause reduced oxygen content in the blood and a drop in blood pressure. Patients suffering from a nut allergy are often sensitive to this active ingredient. It should not be used at all by people who are allergic to soy.

Since many products now contain soy, the lifestyle of the patients is sometimes complicated. Those affected can no longer consume the majority of the ready meals on offer and most sports or protein products. Eating in canteen kitchens is often almost impossible.

When should you go to the doctor?

If symptoms occur after consuming soy products that indicate an intolerance or a real allergy to soybeans, a doctor’s visit should not be delayed. It can be an isolated event or a cross-allergy related to a pollen allergy. In this case, the soy allergy would be more dangerous.

The problem is the occurrence of soy in processed foods. Soy is not only consumed in large quantities by vegans. Many people who eat normally do not even know which products from their daily consumption contain soy components. In the case of an allergy, however, this awareness is essential. Proteins contained in soy are responsible for allergic symptoms.

Primary soy allergy affects infants who suffer from cow’s milk allergy. It therefore requires an immediate doctor’s visit and a switch to almond or oat milk. Later, the allergic reactions can dissipate again because the intestinal system has matured. Secondary soy allergy is pollen-associated. Here the multitude of cross-reactions is the reason why the doctor should be consulted.

Workers who deal with bulk goods containing soy are mostly affected by an inhalational soy allergy. Here, the soy allergy can even lead to disability. It makes sense to see a doctor as soon as possible because ignoring symptoms such as swelling of the airways, hives or shortness of breath can become dangerous.

Treatment & Therapy

First and foremost, the therapy deals with the fact that foods containing soy must be avoided. This is difficult, especially at the beginning: Many foods contain soy components, so that those affected have to pay attention to which products they are allowed to eat and which are not.

If there is a soy allergy, numerous foods must be removed from the menu. These include soy flour, soy beans, soy sauces, soy sprouts or various other soy products that are primarily intended to replace dairy products such as soy yoghurt, soy milk, soy ice cream or soy cream. In addition, soy is also found in many chocolates (lecithin); as well as in products containing the additives E 426 and E 322.

These should be avoided if possible – behind these key figures there are also soy components that can trigger an allergic reaction. There is no cure or various other treatment methods for the sufferer to consume the soy products. However, studies have found that strict diets can help.

Affected people who have taken care not to consume soy products have been able to eat small amounts of soy again over time. However, it is advisable if the allergy sufferers are careful not to consume any soy ingredients at all. In this way, any allergic reactions, which can sometimes be life-threatening, can be prevented.


Prevention must begin in childhood. The human immune system develops in childhood; During this time, the immune system is strengthened and subsequently expanded. According to various studies, prolonged breastfeeding should help the child become “immune” to allergens.

In addition, there should be no excessive intake of soy; if too much soy is consumed, the body can – at some point – activate its immune system against the product, resulting in a soy allergy. Other measures that prevent soy allergy are sometimes not known.

Food allergies affect those affected primarily in terms of their diet if there were no previous intolerances. That is why the family doctor instructs him in the course of aftercare in changing his diet.


The allergy sufferer can contact the doctor if they have questions about a soy-free diet. Alternatively, consult a nutritionist or an allergist. How much the allergy restricts the patient depends on his previous eating habits. Anyone who has previously consumed soy products frequently and suffers from an intolerance should avoid these foods in the future.

Substitute products can make this transition easier. An allergy sufferer who has not previously drunk soy milk or cooked with tofu needs to be aware of the possibility of cross-contamination. Foods that are not made from soy can also contain soy residues.

Particular caution is indicated when visiting restaurants, because in this case the patient cannot control the processes in the kitchen. Traces of the allergen in other dishes cannot be ruled out here. The doctor prescribes an emergency medication for the person concerned if he accidentally ingested soy. Anaphylactic shock can be avoided with the drug.

You can do that yourself

If a soy allergy is diagnosed, it is important to ensure that there is no contact with the legume in everyday life. Food must be checked for its ingredients. When buying products, the leaflet should be read carefully. Even with minimal amounts of soy in a product, it should not be consumed.

Greater vigilance must be exercised before consumption, especially when consuming meals that are not self-prepared. A meal in a restaurant or with acquaintances should always be combined with asking about the ingredients used. The chef should be informed about the allergic reaction so that he can take this into account when preparing the meal. The person concerned should make sure that he asks directly whether products containing soy have been used. This is necessary to avoid misunderstandings in everyday life. In addition, the use of well-known foods that have been refined with soy should also be questioned.

If the affected person first notices an allergic reaction, the food supply must be stopped immediately. Cross-allergies occur in a large number of those affected. For this reason, an allergy test should be carried out at an early stage to find out whether there are other allergic reactions. In order to avoid loss of quality of life, alternative preparations should be used.

Soy Allergy