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Anaphylaxis is a severe and often life threatening allergic reaction. It’s a rare condition that is triggered when the body's immune system overreacts. Severe anaphylaxis always requires medical emergency treatment.

Do not delay treatment.

What is anaphylaxis?

Anaphylaxis is a sudden and often severe allergic reaction. It's a life threatening reaction that always needs medical emergency treatment. 

These allergic reactions can happen when a person with allergies comes into contact with the thing they’re allergic to (i.e. an allergen such as insect stings). 

People who have experienced a sudden allergic reaction previously are at risk of developing anaphylaxis, even if they’ve not had an anaphylactic reaction before. 

A severe anaphylactic reaction can occur almost immediately, or it can take up to 3 hours for severe symptoms to develop, but when it does, it can progress quickly. 

If you’ve experienced a severe allergic reaction previously, speak to your GP or healthcare providers and request a referral to an allergy clinic with an allergy specialist. 

What causes anaphylaxis?

Common causes of anaphylaxis include:

  • Foods - celery, gluten, crustaceans, eggs, fish including shellfish and molluscs, milk, mustar, peanuts, sesame, soybeans, sulphur dioxide and sulphites.
  • Medicines - antibiotics, NSAIDS (non steroidal anti-inflammatory drugs such as aspirin)
  • Insect stings and bites - wasp stings, bee stings, ant bites.
  • General anaesthetic.
  • Contrast dyes.
  • Latex - rubber found in condoms and rubber gloves.
  • Exercise and aerobic activity such as running - this is rare, but it’s been known to trigger anaphylaxis.


The time of onset of anaphylaxis will depend on the type of trigger that caused it.

For example, general anaesthetic will cause a faster onset reaction than an insect sting which will cause a faster onset reaction than a food allergy.

When the cause of anaphylaxis isn’t known, this type of anaphylaxis is known as idiopathic.

If you aren’t sure what’s triggering your anaphylaxis, ask your GP to request a referral to an allergy clinic for allergy testing to look at possible causes. 

What are anaphylaxis symptoms?

Anaphylaxis can be triggered immediately, or it can take a few hours to develop, but gets worse very quickly. 

Common symptoms of anaphylaxis include:

  • Feeling dizzy, lightheaded or faint
  • Runny, stuffy nose or sneezing
  • Having difficulty breathing, for example shallow, quick breathing
  • Narrowing of the airways
  • Wheezing/trouble breathing/tight chest
  • Swollen tongue or throat
  • Swelling around the eyes, lips or face
  • Racing heartbeat
  • Weak pulse
  • Skin reactions including - itchy raised hives, rash, pale skin, flushed skin, clammy skin
  • Low blood pressure - hypotension
  • Feeling sick/being sick/nausea
  • Diarrhoea
  • Stomach pains
  • Tingling hands, feet or mouth
  • Confusion, anxiety or lack of mental clarity
  • Sense that something is wrong with your body
  • Collapse
  • Unconscious


Be aware that skin changes without any airways, breathing or circulatory problems does not indicate anaphylaxis. 

Tell me the first sign of anaphylaxis?

There is no definitive initial symptoms of anaphylaxis.

However, early anaphylaxis symptoms can look like a typical allergic reaction: runny nose or a skin rash.

Within about 30 minutes of these symptoms, more severe symptoms can appear, including shock and loss of consciousness. 

What is anaphylactic shock?

Anaphylactic shock is a complication of anaphylaxis.

People with anaphylaxis will experience the normal symptoms first before anaphylactic shock occurs. 

Anaphylactic shock is when the immune system floods the body with chemicals to try and mitigate against the allergen the person is allergic to.

When the body goes into anaphylactic shock, blood pressure drops suddenly, the airways narrow and can prevent normal breathing. 

Anaphylactic shock is incredibly dangerous and requires immediate emergency treatment. If it isn’t treated immediately, it can trigger even more serious complications and cause death. 

Common triggers and risk factors for anaphylactic shock include: 

  • Experiencing anaphylactic reaction before
  • Known allergies
  • Allergy asthma
  • Family history of anaphylaxis


What to do if someone has suspected anaphylaxis

Anaphylaxis needs medical assistance immediately. Anaphylaxis is very serious and must be dealt with quickly with emergency treatment. 

Call 999 and request emergency medical assistance. 

If you’re with someone who has symptoms of anaphylaxis, or you’re having an anaphylactic reaction yourself and you’re able to, follow these steps:

  1. Use an adrenaline auto-injector such as an epinephrine injection pen (if the person has one to hand). Press the pen into the person’s thigh and depress the plunger. You have to know how to use it correctly before you try to administer it. 
  2. Call 999 for an ambulance - tell the emergency responder that the person has anaphylaxis. Even if the person starts to feel better, make sure they seek medical assistance as there’s a risk of anaphylaxis recurring - known as biphasic anaphylaxis.
  3. Remove the trigger if you know what it is, i.e. a bee sting stuck in their skin. 
  4. Lie them down on their back and raise their legs. If they’re having breathing difficulties, keep them sitting up as this can help them breathe. 
  5. For pregnant women, lie them on their left hand side. 
  6. If you’ve administered the epinephrine autoinjector, give another injection 5 minutes after the first one if symptoms have not improved and you have a second injection to deliver. 
  7. Continuously monitor their pulse rate and breathing. If necessary, carry out CPR or other first aid measures until paramedics or medical professionals arrive. 

Some people will experience a second round of anaphylaxis within 12 hours of the first one. This is known as biphasic anaphylaxis. 

If you suffer with anaphylaxis, it can be a good idea to create an anaphylaxis emergency action plan.

What is the best anaphylaxis treatment?

During an anaphylactic reaction, you might stop breathing, or your heart can stop beating. Emergency responders may need to perform CPR. They might also administer medication to relieve symptoms such as: 

  • Epinephrine - this reduces the body’s allergic response to the allergen 
  • Oxygen - to aid breathing
  • Intravenous (IV fluids) antihistamines and/or cortisone - to reduce inflammation of the airways and aid breathing
  • Beta-agonist (for example, albuterol) - to aid breathing


Adrenaline injections

There are 3 main types of adrenaline auto-injectors. All of them are used in slightly diff