How to treat a spider bite and symptoms to look out for

A common house spider can still bite, although it’s not  dangerous to most people but can still be painful  (Alamy Stock Photo)
A common house spider can still bite, although it’s not dangerous to most people but can still be painful (Alamy Stock Photo)

Although extremely rare, spider bites could lead to dangerous outcomes in the UK and, with more than 650 different species of spiders, it’s important to know which ones can cause problems.

In the UK, the list of spiders that could potentially cause health issues include the false widow, the tube web, woodlouse spider, cardinal spider, the walnut orb-weaver Spider, wasp spider, black lace-weaver, the cross spider, the giant house spider and cellar spider, lace-webbed spider, the zebra-back Spider - and even the innocuous-looking money spider.

However, although most of these spiders are venomous, their jaws cannot break human skin in the UK.

That being said and depending on the spider and its victim, spider bites can cause anything from mild itching and redness to an allergic reaction that becomes a medical emergency and could possibly result in death, such as anaphylaxis.

For instance, a student from the University of Hull died after being bitten by a spider in October last year, an inquest into his death has found.

Harry Bolton, 19, was said to have died from sepsis following the bite in his shared student house, where the students had already complained about spider invasions.

Although not directly attributed to the spider, it is something to be aware of, further highlighting the importance of treating spider bites quickly, knowing when it could be something serious, and spotting unusual symptoms.

Residents of the student accommodation on Cottingham Road, Hull, East Yorkshire, had lodged several complaints regarding a sudden invasion of spiders in their dorms but an inquest heard a previous inspection found no infestation.

Police and paramedics were called to the scene and discovered a £1 coin-size gape wound on Mr Boulton’s back, which appeared to be infected.

Four days prior, he had complained about a spider bite on his back, and said that he was not feeling well.

Mr Boulton had gone to Hull Royal Infirmary that evening, presenting symptoms of a high temperature and fast heartrate.

Coroner Paul Marks determined that Mr Bolton’s death was caused by sepsis due to an acute chest infection caused by an infected wound on his back.

“Had he not been bitten by an invertebrate, possibly a spider, he would not have died at that time. It is an incredibly unfortunate case. He had a promising future ahead of him,” said Dr Marks.

How to identify a spider bite

Most spider bites only cause minor symptoms, like red skin, swelling, and pain at the site. You can tell you’ve encountered a spider bite because you’ll be able to see faint puncture marks in your skin. False widow spiders, so-called because of their similarity to the more venomous black widow spider, are the main culprits of UK bites and typically give bites that cause pain, redness, and swelling.

The black widow's bite, which shows up as two puncture marks, may or may not be painful at first. But 30 to 40 minutes later, you may have pain and swelling in the area. Within eight hours you may experience muscle pain and rigidity, stomach and back pain, nausea and vomiting, and breathing difficulties. You might not have seen the spider that bit you, but always seek medical attention immediately if there's a possibility you could have been bitten by a venomous spider and are having a reaction.

If you suspect that you were bitten by an arachnid, and can see the spider, use the gallery below to confirm its identity.

Spiders - in pictures

Grass Spider (Rex)
Grass Spider (Rex)
Black widow spider (Rex)
Black widow spider (Rex)
Silverback trapdoor spider (Rex)
Silverback trapdoor spider (Rex)
Deadly mouse spider (Rex)
Deadly mouse spider (Rex)
St Andrews cross spider (Rex)
St Andrews cross spider (Rex)
European Garden Spider (Rex)
European Garden Spider (Rex)
Brown Huntsman Spider (Rex)
Brown Huntsman Spider (Rex)
Female wolf spider (Rex)
Female wolf spider (Rex)

How to treat a spider bite

1. Wash the bite area with cool soapy water.

This will clean the wound and help prevent infection.

2. Apply a cool compress, such as an ice pack.

This will ease the pain of the bite and help the swelling go down.

3. Elevate bitten extremities.

This is helpful for reducing inflammation and swelling. Tie a snug bandage above the bite if you think you’ve been bitten by a dangerous spider.

4. Relieve minor symptoms of pain using painkillers.

Children or teenagers recovering from chickenpox or who have flu-like symptoms should not take aspirin.

5. Seek urgent medical care.

Call emergency medical services immediately if the person with the spider bite has the following symptoms:

  • Difficulty breathing

  • Nausea

  • Muscle spasms

  • Lesions

  • Tightening in the throat that makes it hard to swallow

  • Sweating profusely

  • Feeling faint

6. Monitor the bite for the next 24 hours to ensure symptoms don't worsen.

Within a few days, the swelling should go down and the bitten area should feel less painful. See a doctor if symptoms don't improve.

You can take preventative steps to stop spiders entering your home by following the steps in this guide.

“Bites from spiders in the UK are uncommon, but some native spiders – such as the false widow spider – are capable of giving a nasty bite,” says the NHS.

The national health body added: “Some spiders’ bites can cause you to feel or be sick, sweating, and dizziness. Bites can also become infected or cause a severe allergic reaction in rare cases.

“Get medical help immediately if you have any severe or worrying symptoms after a spider bite.”