Food allergy symptoms

The symptoms of food allergy range from mild discomfort to a severe, life-threatening reaction called anaphylaxis, which requires immediate medical treatment.

The most frequent symptoms of food allergies are itching or swelling of the mouth. Other symptoms include sneezing, blocked nose, a rash or hives, and stomach upset.

Symptoms usually begin within the first 5-30 minutes of exposure, but may occur up to several hours later (Rutkowski, Dua and Nasser, 2012).

The symptoms arise every time the allergic person eats the offending food. However, if they are allergic to a food that is cross-reacting with pollen they may only experience symptoms in the pollen season. 

Different kinds of food poisoning can provoke symptoms that are similar to the symptoms experienced in food allergy. In order to distinguish between a food allergy and food poisoning the person with symptoms needs to see a doctor. 

Allergic reactions to foods may occur within a few minutes after eating the food, but rarely symptoms may also develop after hours, making the relationship with ingestion of food less clear.

Symptoms generally disappear within hours but can last for days. The specific symptoms and severity of an allergic reaction are affected by:

• the type and amount of the allergen consumed;
• the form in which the food containing the allergen was eaten;
• the intake of alcohol, aspirin and other drugs such as beta-blockers and ACE inhibitors;
• exercise;
• stress;
• the sensitivity of the allergic person.

The symptoms may appear in different parts of the body:

Anaphylaxis

Anaphylaxis is an uncommon, acute, potentially life-threatening and sometimes fatal allergic reaction involving the whole body.

The skin itches, the affected person becomes unwell and dizzy, they feel their heart beating, they feel nauseous, and everything may go black. At the same time they may get nettle rash, hay fever, and suffer an asthma attack. Their blood pressure may drop, and they may faint. Untreated anaphylaxis can rapidly result in death.

In Europe and the US, peanut and tree nuts are the foods most commonly reported to cause anaphylaxis. Prompt administration of adrenaline after eating suspected problem foods and transport to an emergency department has helped minimise life-threatening episodes.

Food allergies are one of the most common causes of anaphylaxis and account for approximately 30% of all fatal cases of anaphylaxis (Lieberman et al. 2010). Within in the United States, peanut induced anaphylaxis alone, affects 1.5 million people and leads to between 50-100 deaths each year (Wen et al. 2007).

Anaphylaxis can be persistent and reoccurring up to 8-12 hours after an initial attack (reoccurrence occurs in approximately 20% of cases). These effects cannot be predicted from the severity of the initial phase of anaphylaxis (Kemp and Lockey, 2002).

According to the Network for Online Registration of Anaphylaxis database, individuals with pre-existing cardiovascular conditions are associated with the most severe allergic reactions.