Symptoms
The patient experiences rapidly developing airway/breathing problems and/or circulation problems which are usually associated with skin and mucosal changes.
Symptoms of anaphylaxis generally begin within minutes to an hour of exposure to a trigger.16,28 Anaphylaxis can cause the following symptoms in the body:
| Body system | Symptoms |
|---|---|
| Skin | Pruritus (including genitalia), erythema, urticaria, or angio-oedema |
| Eyes | Periorbital pruritus, erythema and oedema, lacrimation, or conjunctival erythema |
| Ear, nose and mouth | Sneezing, rhinitis, nasal congestion, pruritus of the lips, tongue and palate, angio-oedema of the lips and tongue, sensation of pruritus of external auditory canal, or a metallic taste |
| Lungs and throat | Dyspnoea, dysphagia, dysphasia, dry staccato cough, chest tightness, wheezing/bronchospasm, increased mucus production, laryngeal oedema or pruritus, “tightness” in the throat, hoarseness/stridor, dysphonia, or a sensation of choking |
| Heart and circulation | Dizziness, weakness/lethargy, syncope, tachycardia, bradycardia, arrhythmia, chest pain, or hypotension |
| Digestive system | Nausea, vomiting, abdominal cramps, or diarrhoea |
| Nervous system | Anxiety, confusion, “aura of doom” |
| Other | Uterine contractions, incontinence |
However, not all patients will experience all of these symptoms. Two patients who experience anaphylaxis may have entirely different symptoms: one may experience urticaria and vomiting; the other may experience respiratory distress. Also the same individual may not experience the same symptoms each time they have a reaction, even if it is to the same antigen.
Skin symptoms and signs, including generalised urticaria, flushing, itching and angio-oedema are the most common manifestations of anaphylaxis (occurring in 90% of those affected), followed by respiratory (70%) and gastrointestinal (40%) symptoms.29 Hypotension occurs in 10-30% of cases. Although the majority of anaphylactic episodes include skin symptoms, their absence does not rule it out. Severe episodes are characterised by rapid cardiovascular collapse and shock can occur without cutaneous manifestations.30
- The median time to respiratory or cardiac arrest following exposure is:
− 30 minutes for foods (range 6 – 360 minutes)
− 15 minutes for venom (range 4 – 120 minutes)
A more severe form of anaphylaxis can result in sudden collapse without any warning symptoms. This form of anaphylaxis occurs most commonly after a person is given a medication into a vein or is stung by an insect.
Any delay in the recognition of the initial signs and symptoms of anaphylaxis can result in a fatal outcome either because of airway obstruction or vascular collapse. The most dangerous symptoms of an allergic reaction involve breathing difficulties caused by swelling of the airways or a drop in blood pressure indicated by dizziness, lightheadedness, or feeling faint or weak. If untreated, both can lead to death.31
It is important that affected patients learn to recognise the warning signs of anaphylaxis as much as possible, as any delay can lead to death.
- 16 - Mayo Clinic. Anaphylaxis. Available at: www.mayoclinic.com/health/anaphylaxis/DS00009/METHOD=print.
- 28 - Cox L et al. Ann Allergy Asthma Immunol. 2008;101:580–592.
- 29 - Sheikh A, Shehata YA, Brown SGA, et al. Cochrane Database Syst Rev. 2008; Issue 4: CD006312.
- 30 - Lieberman P et al. J Allergy Clin Immunol. 2005; 11 5(3)(suppl):S483-S523.
- 31 - Sampson HA. Anaphylaxis and Emergency Treatment. Pediatrics 2003;111;1601-8.