Anaphylaxis in Sport

Anaphylaxis is a clinical diagnosis and the precise definition does not matter while it is happening. The shape is what matters: sudden onset, rapid progression, and a problem with the airway, breathing or circulation.

The airway gives swelling of the tongue and throat, hoarseness, difficulty swallowing and stridor. Breathing gives wheeze, tachypnoea, fatigue and cyanosis. Circulation gives pallor, clamminess, hypotension, faintness and collapse.

Skin and mucosal changes accompany most reactions and are usually the first thing anyone notices, but they are not required. Treating because of a rash, and waiting because there is not one, are both errors, and the second one kills.

Gastrointestinal symptoms need care. Nausea, abdominal pain and vomiting, with no airway, breathing or circulation problem, do not usually indicate anaphylaxis. But abdominal pain and vomiting can be anaphylaxis after an insect sting, and a sting is a realistic pitchside trigger.

The mimics worth carrying in an athlete: exercise-induced bronchoconstriction, which wheezes but brings no swelling, no urticaria and no hypotension; exercise-associated collapse; and cardiac arrest.

Call 999 and give adrenaline. Both happen immediately, and the drug goes intramuscularly into the anterolateral thigh as soon as an airway, breathing or circulation problem is recognised. Remove the trigger where that is quick and feasible, but never delay adrenaline to hunt for a sting.

The dose for an adult or a child over 12 is 500 micrograms, which is 0.5 millilitres of 1 in 1000, although a small or prepubertal child over 12 gets 300 micrograms. A child of 6 to 12 gets 300 micrograms, a child of 6 months to 6 years gets 150, and a child under 6 months gets 100 to 150.

Repeat after five minutes if airway, breathing or circulation problems persist. Skin symptoms that have not settled are not, on their own, a reason to give a second dose.

Position is treatment rather than comfort. Lie the athlete flat and raise their legs. Where breathing is the dominant problem, sitting up may help, but they do not stand and they do not walk off the pitch. The athlete who insists they are fine and gets to their feet is a real scenario and a dangerous one.

Then monitor, give high-concentration oxygen where it is available, and give intravenous crystalloid early where there is hypotension or a poor response. Two doses without improvement is refractory anaphylaxis, which needs specialist help, fluids and an adrenaline infusion from someone experienced; intravenous adrenaline is not a pitchside intervention. If cardiac arrest supervenes, start chest compressions and defibrillate, and do not let an intramuscular injection interrupt the resuscitation.

What is not in the initial treatment has changed, and it is worth being deliberate about. Antihistamines are not part of it, although a non-sedating oral antihistamine may treat persistent skin symptoms once the athlete is stable. Corticosteroids are no longer advised for the routine emergency treatment of anaphylaxis, and one may be considered in a refractory reaction after adrenaline and fluids, never in place of them.

The pack, since somebody has to own it: two ampoules of 1 in 1000 adrenaline, needles, graduated 1 millilitre syringes, and masks. Chlorphenamine and hydrocortisone do not need to be in it. Expiry dates get checked.

A legal point that matters at a community club: a competent person may give adrenaline from an emergency stock to save a life without a Patient Group Direction. A named-patient auto-injector is different, and should be used only on the person it was prescribed for.

The auto-injector is not the dose you want. Most adult devices deliver 300 micrograms against a recommended 500, and coronial inquests have identified that this can result in substantial underdosing which may contribute to fatal outcomes. Some 500 microgram devices exist, and the standard needle may not reach muscle in a larger athlete. So if you have an ampoule and a syringe, draw it up. If you do not, use whatever auto-injector is available immediately and be ready to repeat. Nobody dies of the wrong dose given fast; they die of the right dose given late.

Exercise is itself a trigger. Exercise-induced anaphylaxis occurs during or shortly after exertion. Food-dependent exercise-induced anaphylaxis occurs only when a specific food, most classically wheat, has been eaten in the hours beforehand: the athlete tolerates the food at rest and tolerates the exercise fasted, and only the combination does it. That is why it gets missed, and why the history has to ask about food and exercise together rather than separately. Cofactors lower the threshold, and non-steroidal anti-inflammatory drugs, alcohol and heat are the ones an athlete meets. Management is avoiding the combination, carrying an auto-injector, and not training alone.

And adrenaline is prohibited. It is a stimulant, exempt from the prohibited list only in local administration such as nasal, ophthalmic, or given with a local anaesthetic, so intramuscular adrenaline for anaphylaxis is prohibited in competition. Treatment is never delayed for that. Give the drug, document the emergency properly, and take advice from UK Anti-Doping or the international federation afterwards about whether a retroactive therapeutic use exemption is required.

Afterwards, suspected anaphylaxis goes to hospital and is observed rather than sent home, for a period set by the reaction and the athlete's risk. Mast cell tryptase supports the diagnosis but neither confirms nor excludes it, and a normal level does not rule anaphylaxis out. In an adult or young person of 16 or over, a sample is taken as soon as possible after emergency treatment has started, and a second ideally within one to two hours, and no later than four, from the onset of symptoms. A baseline is taken later, at specialist allergy follow-up, and every athlete is referred.

• •Resuscitation Council UK's guidance on the emergency treatment of anaphylaxis sets the adrenaline doses and route, the criterion for repeating at five minutes, the position, and the exclusion of routine corticosteroids and acute antihistamines.
• •Resuscitation Council UK's supporting guidance covers the auto-injector dose gap, the anaphylaxis pack contents, and the position on Patient Group Directions.
• •Current NICE guidance on anaphylaxis sets the mast cell tryptase sampling times, and the observation and referral to specialist allergy services that follow emergency treatment.
• •The World Anti-Doping Agency prohibited list exempts adrenaline only in local administration, which leaves intramuscular use for anaphylaxis prohibited in competition.

• •Anaphylaxis is sudden onset and rapid progression with an airway, breathing or circulation problem.
• •Skin changes are common but can be absent, and their absence excludes nothing.
• •Adrenaline 500 micrograms intramuscularly into the anterolateral thigh, and call 999 at the same time.
• •Repeat at five minutes only if airway, breathing or circulation problems persist, not for skin alone.
• •Antihistamines and corticosteroids are not part of the initial emergency treatment.
• •An adult auto-injector usually gives 300 micrograms against a recommended 500.