- Conditions & treatments
National Poisons Centre
The New Zealand National Poisons Centre has a factsheet on Spiders in New Zealand, including information on what to do if you are bitten by a redback or katipo spider. Contact the Poisons Centre on 0800 POISON (0800 764 766).
Most spiders in New Zealand are harmless, but the katipo, redback and white-tailed spiders can be harmful and should be avoided.
- It’s rare for significant problems to result from a spider bite.
- Always try to capture the spider and take it with you when you seek medical help.
Female katipo spider, photo by Jess Costall / CC BY 2.0.
Redback and katipo spiders
These spiders are dark brown with a round abdomen the size of a small pea, with a red (redback) or orange (katipo) mark on the back. Only the females bite and although the bite can be painful and distressing, it is very rarely fatal.
Symptoms develop over an hour with increasing pain, sweating and redness with a pale centre around the bite. The pain progresses up the limb over a number of hours and may develop into severe crushing chest pain or acute abdominal pain.
If you’re sure you or a family member has been bitten by a redback or katipo, and the symptoms are becoming unpleasant, go to the emergency department straight away. The available antivenom is safe and effective.
Most white-tailed spider bites are harmless, but just occasionally a severe reaction may result in a deep ulcer or wide area of skin necrosis (where the area of skin and flesh around the wound dies).
Self care for spider bites
Local pain can be expected for several hours and mild swelling for one to two days.
- To relieve stinging use an anti-sting ointment such as Soov (unless the bite is near your eyes), a paste made of baking soda and cold water, or an ice cube for 20 minutes.
- Apply ice compresses every two to three hours to reduce swelling and pain.
- If necessary, take pain relief such as Panadol.
- Antihistamines such as Telfast, Claratyne and Phenergan may relieve itching and swelling. A cream with hydrocortisone will reduce inflammation. You can get these from your pharmacy.
Always try to catch and keep the spider in case you need to see a doctor.
Call 111 for an ambulance if you or someone else has been bitten and has symptoms of a serious allergic reaction or anaphylaxis.
These symptoms include:
- swelling around the lips and eyes
- rapid development of a rash
- shortness of breath or wheezing
- chest tightness
- severe dizziness or faints
- persistent sneezing or coughing
- hoarse voice
- difficulty swallowing or throat tightness
- signs of shock (pale skin, rapid pulse and fainting).
- Do not give aspirin (acetylsalicylic acid) or aspirin-containing products to anyone 18 years or younger because of the risk of a serious illness called Reye's syndrome.
Take non-steroidal anti-inflammatory drugs (NSAIDs) with food or milk to prevent stomach irritation. Do not give NSAIDs to anyone with:
- NSAID-induced asthma
- increased risk of bleeding, such as ulcer disease, a bleeding disorder, if taking blood thinners (anticoagulants), or following surgery, significant trauma or major dental work
- an allergy to NSAIDs.
When to see your doctor
Call your doctor if you have been bitten and have:
- swelling in your eyelids, lips or genitals
- signs of poisoning (especially if an older person has been bitten): abdominal pain, muscle cramps, nausea, vomiting, sweating, droopy eyelids, anxiety and restlessness, or excessive saliva (dribbling, drooling)
- signs of infection: increasing pain, redness, swelling, red streaks leading away from the bite, heat, discharge of pus, fever or chills
- for a white-tailed spider bite, an ulcer, blister or blackened skin (this is a sign of necrosis)
- pain that is not controlled by following the self-care instructions
- any new or worsening symptoms.
You should also see your doctor if you are not properly immunised against tetanus as a spider bite can be an entry point for the tetanus bacteria.