The symptoms of anaphylaxis usually start between three and 60 minutes after contact with the allergen. Less commonly, they can occur a few hours or even days after contact.
When you have an anaphylactic reaction, you may feel unwell or dizzy or may faint because of a sudden drop in blood pressure.
Narrowing of the airways can also occur at the same time, with or without the drop in blood pressure. This can cause breathing difficulties and wheezing.
You may also experience any of the symptoms below:
- swollen eyes, lips, genitals, hands, feet and other areas (this is called angioedema, see useful links),
- itching
- a strange metallic taste in the mouth,
- sore, red, itchy eyes,
- changes in heart rate,
- a sudden feeling of extreme anxiety or apprehension,
- itchy skin or nettle-rash (hives),
- unconsciousness due to very low blood pressure,
- abdominal cramps, vomiting or diarrhoea, or
- nausea and fever.
Anaphylaxis varies in severity. Sometimes it causes only mild itchiness and swelling, but in some people it can cause sudden death.
Anaphylaxis can lead to death if breathing becomes severely obstructed or if blood pressure becomes extremely low (known as shock).
If symptoms start soon after contact with the allergen and rapidly get worse, this indicates that the reaction is more severe.
