Factors that may affect an allergic reaction

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People with food allergies often find that on different occasions, they have had very different reactions when they accidentally eat their allergen or food they are allergic to.

Factors have been identified that can change how a person reacts when they have eaten their allergen. Some of these factors are related to the food itself, while others are not. Of these factors, some are supported by research, and others by expert opinion.

Factors that may affect the severity of an allergic reaction include:

Exercise

Exercise (being physically active) is the most well-described and reported factor that can affect the severity of an allergic reaction. Activity or exercise can worsen an allergic reaction in anyone who is at risk of anaphylaxis when they are exposed to their allergen (that is when they have eaten the food they are allergic to or been stung/bitten by an insect they are allergic to, for example).

The advice if you are having an allergic reaction that can lead to anaphylaxis, is to stay calm and rest because exercise (being physically active) can make an allergic reaction worse, more quickly

• Sit quietly and try to remain calm
• Tell someone what’s happening so they can help you if the reaction gets worse
• Do not panic, race around or ignore the symptoms
• Sit, lay quietly and take slow, deep breaths to help you stay calm
• If it is a child who is having a reaction, calmly sit with them with a story book, a puzzle or watch TV. Do not let them climb the play gym or run around. Encourage quiet play and stay with them in case the reaction gets worse
• Always follow instructions on your ASCIA Action Plan and monitor for any further signs of anaphylaxis

Activity or exercise can worsen an allergic reaction in anyone who is at risk of anaphylaxis. This response to activity/exercise is NOT the same as a diagnosis of Exercise-Induced Anaphylaxis (EIA) or Food-Dependent Exercise-Induced Anaphylaxis (FDEIA).

See information on Exercise-Induced Anaphylaxis

Being unwell with a virus or other illness

There is evidence that if a person is unwell, they will be more sensitive to an allergen they accidentally eat, which may lead to a more severe allergic reaction.

• This is why it is recommended that your baby is well when you introduce a common allergy-causing food.
• It is also recommended that a person having an oral food challenge is well on the day of the challenge.

The time of the month for people who have periods

Hormones may play a role in how the body reacts to an allergen. More research is needed into how female hormones impact the severity of an allergic reaction, but it has been observed that some people have more allergic reactions around the time of their monthly period.

Being very tired or stressed

Research has shown that tiredness can affect how an adult may react if they eat a food allergen.

• Tiredness – being tired makes people more likely to react than when they are well-rested.
• Stress – there is less evidence of long-term stress affecting the severity of allergic reactions. Long-term emotional stress is thought to lead to an increase in stress hormones, which in turn affect the immune system, possibly increasing the severity of a reaction.

The amount of allergen eaten

• The amount of food that can cause allergic reactions varies from person to person.
• The severity of the reaction is determined by the quantity of the food allergen consumed – the more you eat, the more severe the reaction will be.
• Some people, though, may experience a severe allergic reaction from a very small amount of allergen.

What sort of food the allergen is in

Whether an allergen is present alone, mixed with other foods, or cooked or raw may affect the severity of a reaction.

• Liquids are absorbed faster, meaning the body is exposed to more allergen in a shorter length of time.
• There are some people who will react to raw food but can eat the food when cooked without having an allergic reaction
  • This is particularly true for certain fruits and vegetables.
  • Egg and milk, especially when baked with flour into cakes or muffins may be tolerated better. It is thought the baking process changes the shape of the egg and milk proteins, which makes it harder for the body to recognise them as allergens. Not all people with milk or egg allergy can safely eat their allergens in baked form. There have been severe reactions to baked egg and baked milk. It is always advised to discuss the introduction of food allergens with your doctor.
• Other foods like peanuts and tree nuts tend to cause reactions whether they are cooked (roasted) or raw.

Drinking alcohol at or around the time you eat the allergen

Alcohol can affect the severity of a reaction in a number of ways:

• Drinking alcohol can lead to poor decision-making and increased risk-taking behavior. For example, people may eat foods they wouldn’t normally eat, or fail to notice early warning signs of a reaction such as an itchy mouth. This may lead them to consume more food than they should before realizing they are having a reaction.
• Alcohol can impact the body by changing food digestion and immune cell function, potentially worsening allergic reactions.
• For more information about alcohol and food allergy click here

Taking some types of medication at the time you eat the allergen

Some medications can impact the severity of allergic reactions if the allergen is accidentally eaten. The most well-known is non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, diclofenac or ibuprofen.

Summary

Factors have been identified that can alter a person’s reaction after consuming their allergen.  Accidents are not planned, and not all allergic reactions are the same, which is why it is important to always carry your ASCIA Action Plan for Anaphylaxis and adrenaline (epinephrine) injector(s) with you.

It is also important to remember that if someone is having a severe allergic reaction, they can become critically unwell if they stand, walk or sit up suddenly because it may cause a serious drop in blood pressure.

Evidence shows that some factors can impact the severity of an allergic reaction. Remembering these factors when assessing risk and planning may be helpful in managing food allergies for yourself or the people you care for.