It can be difficult to know if a bite from a spider is dangerous or not. This article explains the best first aid treatment depending on the type of spider involved.
It’s important to be aware that bites from spiders can cause a severe allergic reaction (anaphylaxis) in some people. Learn more about first aid treatment for severe allergic reactions in the ‘anaphylaxis’ section below.
Different types of spider bites
Spider bites are best considered in three medically relevant groups: big black spiders, redback spiders and all other spiders.
Big black spiders are funnel web spiders and any large black-looking spiders that may be a funnel web spider. Patients bitten by big black spiders must be managed as a medical emergency.
Redback spiders are fairly easy to identify and their bites do not cause rapidly developing or life-threatening effects but many cause significant pain and other problems in your body.
All other spiders in Australia are more or less harmless. If the victim has not been bitten by a big black spider or a redback spider they can be reassured and no further treatment is required.
Funnel web spider
The funnel web spider which is found on the east coast of Australia is the most venomous spider in the world. It's a medium to large spider varying from one to five cm. Male funnel web spiders are more lightly built than female ones. Their body colour can vary from black to brown and the bite from a funnel web spider can be extremely painful.
First aid for a big black spider's bite
Bites from a funnel web or mouse spider can be very dangerous. Provide emergency care including cardiopulmonary resuscitation (CPR) if needed. Calm the person and call triple zero (000) for an ambulance.
Steps to take if someone gets bitten:
- apply a pressure immobilisation bandage
- keep the victim from moving around
- keep the bitten limb down
- bandage the limb from the area of the bite to the hand or foot, then back up to the body
- immobilise the limb by splinting if possible
- tell the victim to keep calm
- do not move them at all
- wait for the ambulance.
Other spider bites
For all other spider bites, including from red-backed spiders, apply a cold compress or ice pack directly over the bite site to help relieve the pain. Seek medical assistance if further symptoms or signs of infection develop.
Cardiopulmonary resuscitation (CPR)
Read these articles for an overview of:
For printable charts, see St John Ambulance Australia’s first aid resuscitation procedures (DRSABCD) poster, as well as their quick guide to first aid management of bites and stings.
Pressure immobilisation bandage
A pressure immobilisation bandage is recommended for anyone bitten by a funnel web or mouse spider.
This involves firmly bandaging the area of the body involved, such as the arm or leg, and keeping the person calm and still until medical help arrives.
First put a pressure bandage over the bite itself. It should be tight and you should not be able to easily slide a finger between the bandage and the skin.
Then use a heavy crepe or elasticised roller bandage to immobilize the whole limb. Start just above the fingers or toes of the bitten limb, and move upwards on the limb as far as the body.
Splint the limb including joints on either side of the bite. Keep the person and the limb completely at rest. If possible, mark the site of the bite on the bandage with a pen.
A guide to pressure immobilisation bandages can be found on the Australian Resuscitation Council website.
Spider bites can be painful. Occasionally some people have a severe allergic reaction to being bitten or stung.
In cases of severe allergic reaction, the whole body can react within minutes to the bite or sting which can lead to anaphylactic shock. Anaphylactic shock is very serious and can be fatal.
Symptoms of anaphylactic shock may include:
- swelling of the mouth, throat or tongue
- difficulty swallowing
- difficulty breathing or shortness of breath or wheezing
- difficulty talking
- a rash that may appear anywhere on the body
- itching – usually around your eyes, ears, lips, throat or roof of the mouth
- flushing (feeling hot and red)
- stomach cramps, feeling or being sick
- feeling weak
- collapsing or falling unconscious.
Call triple zero (000) for an ambulance. If the person has a 'personal action plan' to manage a known severe allergy, they may need assistance to follow their plan. This may include administering adrenaline to the person via an autoinjector (such as an Epipen®) if one is available.
The Australasian Society of Clinical Immunology and Allergy recommends that for a severe allergic reaction adrenaline is the initial treatment. For further information, visit the Choosing Wisely Australia website.
The St John Ambulance Australia first aid fact sheet for bites and stings can be found on their website. For more information on anaphylaxis, including setting up a personal action plan, go to www.allergy.org.au.
Not sure what to do next?
If you are still concerned about your spider bite, why not use healthdirect’s online Symptom Checker to get advice on when to seek medical attention.
The Symptom Checker guides you to the next appropriate healthcare steps, whether it’s self care, talking to a health professional, going to a hospital or calling triple zero (000).
Last reviewed: September 2017