Recognising Anaphylaxis: The Decision That Cannot Wait

Anaphylaxis kills through delay far more often than through inadequate drugs. The pattern in fatal cases is consistent: the diagnosis was considered but not acted on, or treatment other than adrenaline was tried first. Both are recognition failures, which makes recognition the thing worth learning properly.

At a glance

How it actually presents

The combination that defines it is sudden onset with rapid progression, plus compromise of airway, breathing or circulation. Any of the three qualifies, and they may occur in any combination.

• Airway: swelling of the tongue, lips or throat; a sensation of throat closing; hoarseness; stridor; difficulty swallowing.
• Breathing: shortness of breath, wheeze, fatigue with the effort of breathing, cyanosis, falling oxygen saturation.
• Circulation: pallor, clamminess, tachycardia, hypotension, faintness, collapse, reduced consciousness.

Skin and mucosal changes — flushing, urticaria, angioedema — are common and often the first thing noticed. But they are absent in a meaningful proportion of cases, and a patient with sudden breathing difficulty or collapse after an exposure has anaphylaxis until proven otherwise regardless of their skin.

Gastrointestinal symptoms are easily dismissed but genuinely part of the picture, particularly after ingested triggers: abrupt vomiting, crampy abdominal pain, incontinence.

The two errors that cause deaths

Delay. Time to adrenaline is the modifiable factor most consistently associated with outcome. Waiting to see whether it declares itself, waiting for senior review before giving it, or waiting for a test are all forms of the same error. If you are seriously considering the diagnosis, you are already at the threshold to treat.

Treating with the wrong drug first. Antihistamines relieve itch and urticaria. Steroids act over hours. Neither addresses upper airway swelling or circulatory collapse, and neither works fast enough to matter in the first minutes. Giving them instead of adrenaline, or before it, is a recognised contributor to fatal outcomes.

What to do

1. Call for help immediately and put out the appropriate emergency call. Do not manage this alone.
2. Remove the trigger if you can — stop the infusion, stop the injection. Do not delay treatment to hunt for it.
3. Give intramuscular adrenaline without delay, at the dose and site specified in your resuscitation protocol.
4. Position the patient according to their compromise: lying flat with legs elevated if circulatory collapse dominates, sitting up if breathing difficulty dominates, and recovery position if unconscious and breathing. Sudden sitting or standing of a hypotensive patient has been associated with deterioration.
5. Give high-flow oxygen.
6. Establish intravenous access and give fluids as directed by your protocol.
7. Monitor continuously — conscious level, airway, respiratory rate, saturations, pulse, blood pressure, and cardiac rhythm.
8. Repeat adrenaline if there is no improvement, per your protocol’s interval.
9. Escalate to critical care early if the airway is threatened or the patient is not responding.

Every dose, route and interval above lives in your hospital’s resuscitation protocol, and that is the document to work from. Do not administer from memory.

Afterwards

The reaction is not necessarily over. Biphasic reactions — a recurrence after apparent recovery — do occur, so patients require a period of observation determined by your local protocol and the severity of the initial episode.

Document the timeline precisely: time of exposure, time of onset, time of each intervention, and the response. This record matters clinically for the observation decision and matters enormously for the allergy assessment that follows.

Record the suspected trigger prominently in the allergy field, with the reaction described. Ensure the patient is referred for specialist allergy assessment, that they and their family understand what happened, and that adrenaline auto-injector provision and training are arranged where indicated.

What seniors actually ask

• What time did the exposure happen and what time did you give adrenaline?
• What was compromised — airway, breathing, or circulation?
• Did you give it intramuscularly, and where?
• Has it been documented in the allergy record?

Last-minute checklist

• Sudden onset, rapid progression, airway or breathing or circulation compromise
• No skin changes does not exclude the diagnosis
• Call for help; do not manage alone
• Intramuscular adrenaline first, immediately, per protocol
• Antihistamines and steroids never come before it
• Position by compromise; do not sit a hypotensive patient up suddenly
• Observe for a biphasic reaction
• Document the timeline and the allergy; arrange follow-up

References

• Your hospital’s anaphylaxis and resuscitation protocol
• Current national resuscitation council guidance