Food allergies seem to be on the rise, but misconceptions abound, often getting in the way of a condition being properly diagnosed and treated.

According to recent research, up to 35% of people misdiagnose themselves (or their children) with a food intolerance or allergy, then try to manage it themselves rather than seek proper medical advice. So it's time to set the record straight on five of the most popular misconceptions that persist.

1. I have symptoms after food so it must be an allergy

Not necessarily. Adverse reactions to food can occur for a variety of reasons, and all fall within the umbrella term "food hypersensitivity". This includes reactions that involve the immune system, termed food allergy, but also a range of others that don't – often called "food intolerance".

Allergic reactions that involve the antibody Immunoglobulin E are often referred to as IgE-mediated (IgE) allergies and are estimated to affect up to 10% of the UK population.

These cause symptoms that range from mild, such as itchy eyes, to severe, such as anaphylaxis – a serious, swift allergic reaction that can cause severe throat or tongue swelling, difficulty breathing, low blood pressure and ultimately death. These symptoms usually occur rapidly after eating the food in question and when severe, require immediate medical attention.

Other reactions that involve the immune system (called non-IgE mediated allergy) may cause symptoms that are either immediate or slower onset and more chronic in nature – such as red, itchy skin, heartburn or loose stools.

Some of these may be similar to symptoms caused by food intolerances. While totally excluding the trigger food is usually required in IgE allergy, restricting it may be sufficient in other forms of hypersensitivity, but this will depend on the underlying cause.

2. I can just go online and get an allergy test

A trip to the chemist or a browse online for a diagnosis is likely to provide you with a bill and a long list of foods that are apparently causing your symptoms.

Many of the tests offered are not evidence-based for food allergy or food intolerance. These can lead to unwarranted self-imposed dietary restrictions that not only increase the risk of nutritional deficiency, but can cause anxiety, have a detrimental effect on your social life by making eating out tricky, and ultimately affect your quality of life.

The only evidence-based allergy testing currently available is for IgE (immediate reaction) allergy. These are skin-prick tests and specific IgE blood tests.

However, even if IgE testing is offered, the results require careful interpretation as a positive test does not necessarily mean allergy. An "oral food challenge", where precise and increasing doses of the suspect food are given, is considered the best method of diagnosis for food allergy, but these must be performed with medical supervision.

Diagnosis starts with a thorough, allergy-focused history that will point towards appropriate testing if required. This needs to be undertaken by a medical professional with experience in allergy. So if you are concerned about your symptoms, talk to your doctor.

3. I need to avoid lots of foods to help control my eczema

This is unlikely. Food does not cause eczema and there are many environmental triggers implicated in flare-ups, making it difficult to ascertain if cutting out specific foods is actually helping.

You don't need to look far to find books and websites that suggest a variety of implicated foods, but for most people, appropriate medical treatment is the key to controlling the condition.

That said, some people with atopic eczema may need to avoid certain foods due to fast onset and potentially severe IgE food allergy. Additionally, excluding specific foods may be beneficial for some and may involve non-IgE food allergy.

However, this needs careful assessment so if you feel your current treatment for eczema isn't keeping it under control, speak to your doctor before making any dietary changes.

4. 'May contain' warnings are there to protect manufacturers

Allergen food labeling has improved in recent years with the implementation of the 2014 EU legislation which continues to be relevant in the UK as Scotland and the other nations update and improve it in this post-Brexit era.

However, it has limitations. In fact, "precautionary allergen labeling" (trace warnings) is not specifically regulated under the legislation beyond the requirement that voluntary information must not mislead the consumer, be ambiguous or confusing. The wording of warnings is not standardized and crucially, doesn't give an indication of the level of risk.

So it's perhaps unsurprising that this kind of warning is regarded with suspicion by some while being a cause of angst for others, particularly those with potentially severe IgE allergy where even very small amounts of a specific food may cause immediate symptoms.

The safest and for some, necessary, approach is to avoid all products with these warnings. In the end how this is managed is down to personal choice; but understanding what is and isn't required on food labeling is essential to making a fully informed decision about managing what you eat and foods to avoid.

5. Food allergy: you just need to avoid the trigger food

Many people following restricted diets would disagree. Not only is there potential nutritional risk, excluding certain foods requires careful planning and constant vigilance. For those with fast onset IgE allergy in particular, where accidental exposure to the trigger food may cause severe symptoms, this can result in considerable anxiety.

In fact, there is evidence that having potentially severe food allergy has a detrimental effect on quality of life in terms of health. So proper advice and appropriate management is a must.

With an abundance of information available thanks mainly to online sources, it is more important than ever to make sure you use credible, reliable sources and seek proper medical advice and treatment if you are concerned about food-related symptoms.

—Marian Cunningham, Lecturer in Human Nutrition and Dietetics, Glasgow Caledonian University