Anaphylaxis - also known as anaphylactic shock - usually develops suddenly and gets worse very quickly.
Anaphylaxis is a medical emergency. It can be very serious if not treated quickly.
What to do if someone has anaphylaxis
The following advice is issued by the NHS.
If someone has symptoms of anaphylaxis, you should:
:: Use an adrenaline auto-injector if the person has one – but make sure you know how to use it correctly first
:: Call 999 for an ambulance immediately (even if they start to feel better) – mention that you think the person has anaphylaxis
:: Remove any trigger if possible – for example, carefully remove any wasp or bee sting stuck in the skin
:: Lie the person down flat – unless they're unconscious, pregnant or having breathing difficulties
:: Give another injection after 5-15 minutes if the symptoms don't improve and a second auto-injector is available
If you're having an anaphylactic reaction, you can follow these steps yourself if you feel able to.
People with potentially serious allergies are often prescribed adrenaline auto-injectors to carry at all times. These can help stop an anaphylactic reaction becoming life threatening.
They should be used as soon as a serious reaction is suspected, either by the person experiencing anaphylaxis or someone helping them.
Make sure you're aware how to use your type of auto-injector correctly.
There are three main types of adrenaline auto-injector, which are used in slightly different ways.
Instructions are included on the side of each injector if you forget how to use it or someone else needs to give you the injection.
Positioning and resuscitation
Someone experiencing anaphylaxis should be placed in a comfortable position.
:: Most people should lie flat
:: Pregnant women should lie on their left side to avoid putting too much pressure on the large vein that leads to the heart
:: People having trouble breathing should sit up to help make breathing easier
:: People who are unconscious should be placed in the recovery position to ensure the airway remains open and clear – place them on their side, making sure they're supported by one leg and one arm, and open their airway by lifting their chin
:: Avoid a sudden change to an upright posture such as standing or sitting up – this can cause a dangerous fall in blood pressure
If the person's breathing or heart stops, cardiopulmonary resuscitation (CPR) should be performed immediately.
You will need to go to hospital for observation – usually for 6-12 hours – as the symptoms can occasionally return during this period.
While in hospital:
:: An oxygen mask may be used to help breathing
:: Fluids may be given directly into a vein to help increase blood pressure
:: Additional medications such as antihistamines and steroids may be used to help relieve symptoms
:: Blood tests may be carried out to confirm anaphylaxis
You should be able to go home when the symptoms are under control and it's thought they won't return quickly. This will usually be after a few hours, but may be longer if the reaction was severe.
You may be asked to take antihistamine and steroid tablets for a few days after leaving hospital to help stop your symptoms returning.
You will also probably be asked to attend a follow-up appointment with an allergy specialist so you can be given advice about how you can avoid further episodes of anaphylaxis.
Adrenaline auto-injectors may be provided for emergency use between leaving hospital and attending the follow-up appointment.