From the Guidelines
Yes, allergic reactions can have a second phase, and exercise can indeed trigger or exacerbate this phase, as seen in exercise-induced anaphylaxis and food-dependent exercise-induced anaphylaxis, where physical activity either directly triggers allergic symptoms or enhances an allergic response to a food that was consumed before exercise 1. The biphasic allergic reaction occurs when symptoms resolve initially but then return hours later without additional exposure to the allergen. This second phase typically happens 1-8 hours after the initial reaction subsides, though it can occur up to 72 hours later. Some key points to consider in the management of exercise-induced anaphylaxis include:
- Avoiding exercise for 4 to 6 hours after eating, especially if the individual has a history of food-dependent exercise-induced anaphylaxis 1
- Carrying emergency medication like epinephrine auto-injectors at all times, as recommended by guidelines 2, 3
- Having a companion aware of the condition and capable of providing emergency assistance during exercise 2, 3 Exercise can induce this second phase through several mechanisms: it increases blood flow and circulation, potentially redistributing allergens throughout the body; raises body temperature, which can accelerate immune responses; and causes the release of stress hormones that may modify immune function. If you experience allergic symptoms that resolve and then return, especially after exercise, it's crucial to be aware that you may need medical attention even after the initial symptoms have subsided, and to follow the recommended management strategies to minimize the risk of severe reactions.
From the Research
Allergic Reactions and Exercise
- Exercise can induce anaphylaxis, a severe and life-threatening allergic reaction, as seen in exercise-induced anaphylaxis (EIA) 4, 5, 6.
- EIA can be food-dependent or non-food-dependent, with wheat being the most common culprit food in food-dependent exercise-induced anaphylaxis (FDEIA) 4, 5, 6.
Second Phase of Allergic Reactions
- A second phase of an allergic reaction, also known as a biphasic reaction, can occur in some cases of anaphylaxis 7, 8.
- The use of corticosteroids in the management of anaphylaxis may help reduce the risk of biphasic reactions, but the evidence is not conclusive 7.
- Exercise-induced anaphylaxis can also have a second phase, with symptoms recurring after an initial reaction 6.
Management of Exercise-Induced Anaphylaxis
- Management of EIA involves avoidance of eliciting factors, such as certain foods or exercises, and the use of emergency medications like epinephrine 4, 5, 6.
- Antihistamines and corticosteroids may also be used in the treatment of EIA, but their effectiveness is not well established 7, 6.
- Patients with EIA may benefit from allergological diagnostic workup and guidance to avoid culprit foods and exercises 6.