Anaphylactic shock can be life-threatening. Read our guide to familiarise yourself with the causes & the symptoms

Anaphylactic shock, also known as anaphylaxis, is a severe allergic reaction that can develop quickly in reaction to a certain trigger. Substances that trigger allergic reactions are known as 'allergens' and these can come from certain types of food, medicine or an insect sting. Anaphylactic shock will usually develop within minutes of exposure to a particular allergen.

Anaphylactic shock can be life-threatening if not treated as soon as possible. But with swift and proper treatment, the vast majority of people affected will make a full recovery. 

What causes anaphylactic shock?

The most common causes of anaphylactic shock include:

• Insect stings, especially from bees and wasps

• Peanuts and tree nuts, including pecans, cashews and walnuts

• Other types of food, such as milk, shellfish and certain fruits

• Some medicines, such as antibiotics, general anaesthetics, and non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin

Other possible allergens include rubber latex or contrast agents – a group of dyes used in medical tests to help certain parts of your body show up more clearly on scans.

If someone experiences anaphylactic shock and the trigger is unknown, this is referred to as 'idiopathic anaphylaxis'.

What are the symptoms of anaphylactic shock?

Anaphylaxis generally develops suddenly and worsens rapidly. Symptoms include:

• Difficulty in breathing – breathing may be fast and/or shallow, or there may be wheezing

• Feeling faint or lightheaded, or even collapsing and losing consciousness

• Damp, clammy skin

• A fast heartbeat

• Feeling anxious, disoriented or confused

• Other allergy symptoms (such as a rash, swelling, nausea or vomiting)

• Collapsing or losing consciousness

There could also be other general allergy symptoms, such as an itchy, raised rash, feeling or being sick, and stomach swelling or pain.

If you’re experiencing the rapid onset of any, or a combination, of the symptoms above, seek immediate medical attention.

What should you do if someone goes into anaphylactic shock?

Anaphylactic shock is a medical emergency and should be treated promptly. If someone is experiencing symptoms of anaphylaxis, you should:

• Use an adrenaline auto-injector if the person has one. Make sure you know how to use it first

• Call 999 for an ambulance and tell the operator that the person may be experiencing anaphylaxis

• Ask the person to lie down, unless they’re pregnant, unconscious or having breathing difficulties

• Remove the allergy trigger if you can

• If there is another auto-injector available, give a second injection five to 15 minutes later if their symptoms don’t improve

Even if they start to feel better, it’s strongly recommended that they visit their local hospital for observation. This will allow a doctor to assess their condition and treat any remaining or returning symptoms.

Read about anaphylaxis treatments.

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