Emergency advice

Spider bite:

  1. Call 999 for a severe reaction.
  2. Reassure the casualty and help them to sit down.
  3. Raise the affected area.
  4. Place a cold compress or ice pack on the bite.
  5. Monitor breathing and level of response.

What is a spider bite?

Some spider bites can cause serious illnesses and in rare cases be fatal. Bites in the mouth or throat can be particularly dangerous as the swelling can block the airway. If you can, try and find out about any allergies as soon as possible so you are prepared for possible anaphylactic shock (a severe allergic reaction).  

The majority of spider bites in the UK cause an uncomfortable and itchy aread which can appear red or purple which settles within about a week.

What to do

  1. Try to reassure the casualty and help them to sit or lie down.

  2. If possible, raise the affected area.

    • Place an ice pack or cold compress onto the bite or sting for at least 10 minutes so the risk of swelling is reduced.
  3. Monitor the casualty’s vital signs – their breathing, pulse, and level of response.

    • Watch out for any signs of an allergic reaction such as wheezing and/or reddened, swollen, itchy skin.
  4. Call 999 or 112 for emergency help if the casualty shows signs of a severe allergic reaction.

    Take antihistamines for irritation.

    Take paracetamol for any pain.

    Do not give aspirin to children under 16.

    Contact 111 or GP surgery if the bite appears to be infected - hot, swollen, increasing redness. 

Browse our first aid products:

First aid ice packs and heating pads

First aid ice packs and heating pads

Shop now


Related first aid advice

Animal bites

If an animal bite breaks the skin, you need to treat it to prevent the risk of infection. Learn what to do.

Insect stings

Insect stings can be painful but are not usually dangerous. However, stings to the mouth or throat can be more serious. Find out what to do.

Severe allergic reaction

An allergy is an abnormal reaction to an allergen or ‘trigger’ substance. A severe allergic reaction is called anaphylactic shock. Find out what to look for and what to do.

St John Ambulance volunteers providing support