Jogger rushed to hospital after ‘super rare’ allergic reaction triggered by exercise

SINGAPORE – Ms Selina Ang was set for her weekly Tuesday 10km run in the Marina Bay area with her colleagues, but along the way, she developed odd symptoms.

“I was around 7km in when I felt my tongue swelling. It felt weird, but I kept going as I was only 3km away from the end point,” the associate director of marketing, communications and corporate sustainability told The Straits Times.

“However, I had to stop by the time I got to the 8.5km mark because the swelling got worse and began affecting my breathing.”

The 50-year-old felt dizzy, suffered muscle spasms and abdominal cramps, and developed hives.

She told her colleagues, who bundled her into a car and rushed her to the emergency department of Singapore General Hospital (SGH).

There, she was given an adrenaline jab to immediately reverse her symptoms, helping to open her airways and raise her blood pressure.

“An ENT (ear, nose and throat) specialist was later called in to do a scope to ensure there was no more swelling in my throat and airways.

“I was put on several intravenous drips and was in the observation ward in case the symptoms flared up again despite the medications that were administered,” Ms Ang said.

She was sent home only at 1pm the next day, after the swelling in her mouth subsided.

Her diagnosis: Exercise-induced anaphylaxis (EIAn).

Recalling the incident, which happened in February, Ms Ang said: “The senior doctor who saw me at the SGH emergency department told me that EIAn was ‘super rare’ and I was perhaps the first case she had ever seen.”

Someone with this condition can get a severe and potentially life-threatening allergic reaction triggered purely by physical activity.

EIAn is very rare, and while there are theories on what causes it and what the underlying immunological mechanism is, “it is not well studied”, said Dr Yeong Yao Qun, an associate consultant in emergency medicine at SGH.

“The diagnosis of anaphylaxis is a clinical one, made based on possible allergen exposure. In the case of EIAn, the diagnosis of the ‘exercise’ portion is one of exclusion – when no other allergens are identified,” he said.

Treatment depends on the symptoms, which can include itchy skin rashes, swelling of the tongue, lips or throat, trouble breathing, and low blood pressure that may make a person feel dizzy, faint or weak, he added.

After being treated for anaphylaxis and monitored for between four and six hours to ensure there is no recurrence of symptoms after the initial reaction, the patient is discharged and usually referred to an allergy specialist later to identify what might have triggered the reaction.

While anaphylaxis can be induced purely by exercise, there is also food-dependent exercise-induced anaphylaxis.

This, according to Associate Professor Lee Haur Yueh, a dermatologist at SGH, is more common, though also underdiagnosed.

He said wheat products, nuts or shellfish, for example, when eaten by a patient who is already sensitive to them before exercise, might trigger a reaction.

Prof Lee said: “The individual is typically able to tolerate the culprit foods and exercise on their own. However, when these triggers are combined, anaphylaxis or a severe allergic reaction develops.”

This usually happens when the trigger foods are eaten up to four hours before exercise, he added.

Ms Ang said the only food she reacts to is “prawns that are not fresh”.

“I get itchy patches after eating them,” she said, admitting that she had eaten “a couple of battered prawns for lunch before that fateful run in February”.

“It could have triggered my anaphylaxis,” she said, although she was not diagnosed with food-dependent EIAn.

Any patient suspected of having exercise-related anaphylaxis will need a comprehensive allergy evaluation.

“This is a careful (review) and evaluation of possible food-dependent exercise-induced anaphylaxis, which is far more common,” said Prof Lee.

“Blood tests and skin prick tests might identify food triggers, and these triggers should be avoided four to six hours prior to exercise.”

These individuals would be prescribed an EpiPen, a handheld pen-like injection device used to deliver a shot of adrenaline during a severe allergic reaction.

“This should always be carried around,” said Prof Lee. “Exercise should also be done with a companion after medical clearance.”

Ms Ang, who often goes on trekking holidays off the beaten track, has not let her condition stop her.

She is currently in Nepal with her 18-year-old son Caleb Lim, “conquering” the Ghorepani Poon Hill trek – a moderate-level trek in the Annapurna region.

“We are doing this mother-and-son trip before he does his national service,” she said.

For peace of mind, not only for herself but her son as well, she has two EpiPens in her backpack.

She said she appreciated that the emergency department doctor at SGH did not tell her to stop exercising because of her allergy.

“Rather, she asked me to be mindful of what I eat before exercising and also to be aware of my surroundings while I run, as allergens like pollen, dust and insect bites could trigger EIAn.”