Spider bites

Most spiders in New Zealand are harmless, but the katipō, redback and white-tailed spiders can be harmful and should be avoided.

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Katipō spiders

Photo of a katipo spider, which is dark brown with a round abdomen. It has an orange stripe on its back, which is wavy with a white outline.
Female katipō spider, photo by Jess Costall / CC BY 2.0.

Bites

Because of the katipō’s increasing rarity and non-aggressive nature bites are rare.

Typical symptoms of katipō bites include pain at the bite site, which may spread to other areas, becoming more intense over the next few hours. People may also experience sweating, difficulty in breathing and abdominal cramps.

Redback spiders

Photo of a redback spider, which is a dark brown, with long legs and a thin red stripe on its round abdomen.
Redback spider, photo by Repat / CC BY-SA 3.0.

Bites

Redbacks will only bite when disturbed or trapped in clothing, and bites are rare.

The bite feels like a sharp pain similar to a pinprick. The bite may lead to localised redness, pain and sweating. Occasionally the pain and sweating may spread and stomach pain may occur. Aches in muscles and joints, nausea and vomiting, and increased heart rate and blood pressure can result.

White-tailed spider

Photo of a white-tailed spider, which is brown, with reddish legs and a long body. It has a white spot at its 'tail'.
White-tailed spider, photo by Phil Bendle / CC BY-NC-ND 3.0.

The usual white-tailed spider bite can be painful but the initial burning feeling, swelling, redness and itchiness at the bite site usually resolves and there are no long-lasting effects.

White-tailed spider bites are not considered poisonous to humans. A recent Australian study has shown no evidence linking necrotic ulcers (destroyed skin) to white-tailed spider bites.

What to do if you think you have been bitten by a katipō or redback spider

Katipo and redback spiders are the only spiders that cause systemic symptoms such as sweating, vomiting, abdominal pain and fever. Generally these occur quite soon after being bitten. Mild symptoms can generally be managed at home with oral pain relief such as paracetamol and ibuprofen. If symptoms were to become more severe seek medical attention.

DO

  • clean the wound with antiseptic or warm soapy water
  • place ice on the bite prior to travelling (not directly onto the skin - wrap the ice in a tea towel or other cloth to prevent cold burns).

DO NOT

  • apply pressure to the wound
  • consume alcohol after being bitten.

Do not panic as serious reactions are uncommon and unlikely to develop in less than three hours. Hospitals can provide safe and effective treatment. Venom is not always introduced with the bite. If it is, most reactions to the venom are moderate.

What to do if you think you have been bitten by a white-tailed spider

If you suspect you have been bitten by a white-tailed spider only simple first aid is necessary, as with any puncturing of the skin, as these spiders do not cause skin damage or ulcers:

  • clean the bite area with antiseptic or warm soapy water
  • place ice on the bite to reduce any pain or swelling (not directly onto the skin - wrap the ice in a tea towel or other cloth to prevent cold burns).

For any suspected spider bite, see a doctor if the bite area becomes very red or painful, blisters, appears infected, or forms an ulcer.

The National Poisons Centre is available 24 hours a day on 0800 764 766 for advice on first aid and treatment of bites.

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