There are thousands of spiders around the whole world. Spiders inhabit all continents except two poles. There are also rumors that all spiders are venomous and people shouldn’t get in…

Spiders Bite on Humans, Symptoms and Photos

There are thousands of spiders around the whole world. Spiders inhabit all continents except two poles. There are also rumors that all spiders are venomous and people shouldn’t get in contact with them. The truth is that spiders’ bites occur very rarely and in most cases people can’t distinguish between spiders’ and other insects’ bites. Nevertheless, there are really dangerous arthropods and it is important what does a spider bite look like.

Spiders are all Hunters

Spiders are mostly predators. They prey on insects (flies, butterflies, mosquitoes etc.). Many species catch their victims with the help of a web. Having caught a prey, a spider kills it with its venom. Spiders have a very narrow gut that cannot ingest the food. Instead, there is a pair of special glands that injects enzymes, capable to liquid the food. After a while a spider sucks out the prey, leaving only its external husk.

Spiders are various in sizes – from tiny Patu digua from Colombia (0,37 mm) to significant sized species, such as tarantulas (90 mm in body and 250 mm in legs).

So, absolutely all spiders potentially are able to bite. But from 30 000 species, only 100 of them can sting through human’s skin and only 12 of the rest can cause really meaningful danger to our health.

Even those who bite do it only because of self-defense and will never attack humans first. As for the most spread house spiders, they tend to hide in dark, inaccessible places and when found, flee from people as fast as they can, having no intention to deal with a creature, which is hundred times larger than they are.

orange spider on black web

They prey on insects.

Practically all spiders are poisonous. But due to their fragile constitution and small mandibles, they don’t carry significant danger to humans and pets.

As a rule, spiders aren’t aggressive to people until you offend them. Moreover, they eager to avoid a direct contact with humans. Unreasonable aggressive behavior in spiders, which ends in a bite, is a big rarity. Animals unlike humans never do harm without any cause. Consequently, don’t bother a spider and it won’t hurt you.

Which Spiders are Dangerous and Which One are Safe?

Spiders are fused into two big groups:

  • web spinning species,
  • hunting species,

Each of these groups is comprised of both innoxious and poisonous spiders’ types.

Table – Types of spiders most commonly seen in the USA.

NameHabitatFoodAppearanceInteraction with humans
SafeWeb-spinningCommon house spiderFound outdoors – in sheds, garages, piles of woodIndoors – in corners and dark placesInsects, other spiders, lizardsThey have poor eye-sight, cannot see at 4 inches distanceFlee from humans, feign death, bite when grabbed and squeezed
Southern house spiderCommon in southern part of the USAInsectsBlind, can crawl across anything regardless it is alive or deadIf threatened – play death. Mandibles are rather weak to pierce human skin
Daddy Long Legs spiderFound world widePreys on everything that it is not too big, attacks other spidersWaits in the corners hanging downwardsThey are considered venomous, but the fangs are unable to penetrate humans skin.
HuntersWolf spiderThroughout the world under dead leaves and branchesMostly invertebrates (houseflies, crickets, roaches, grasshoppers, and vertebrates (some kinds of lizards)Females carry youths on their backsBites only when disturbed. They produce painful but not dangerous bite.
Jumping spiderLive in tropical, temperate forests, in mountainous regions and desertsFeed on both insects and nectar, never on fruitThey are forward looking and have eight eyes with perfect visionBites only when disturbed or frightened.
TarantulaLives in warm regionsAre often kept as pets. Feed on cockroaches, crickets, beetle larvaeThey are covered with hairs. Live up to 20 years.When scared, they stand on hind legs and kick stingy hairs towards the enemy. In extreme cases tarantulas may bite
DangerousWeb-spinningBlack widow spiderInhabits warm regions and countriesGrasshoppers, caterpillars, other spiders are their favorite foodBlack widow spider is glossy black with no hairs, but with a sign on its back – a red spot on its backThough their venom is much more poisonous than that of rattlesnake’s, these spiders attack people occasionally when feel danger
Brown widow spiderThey inhabit tropical regions in Africa, America, Asia and AustraliaThey prey on insectsBrown widow spider is afraid of humans and tries to retreat or feign deathTheir venom is considered more poisonous than black widow spider’s, but brown siblings have less powerful fangs and inject comparatively less amount of poison. The bites are painful and dangerous mostly for people with allergic reactions.
HuntersBrown recluse spiderThey are found in western and southern United States. Prefer to settle in dry and undisturbed places in the house or in the gardenThey feed on insects. But the spiders may live for six months without food or waterThe distinctive feature is three pairs of eyes.If threatened, they stand into a defensive position or flee, play death or in the last case bite.
Hobo spiderWestern Europe, North-western United States. Mostly found in fields.InsectsThey a distinctive feature – a chevron sign on the back.Their bites are dangerous when the venom is injured. Very often hobo spiders make dry bites.
Common house spider

This is the Common house spider.

What does a Spider Bite Look Like?

People often mistakenly consider that they were bitten by spiders. There is a range of causes which imitate spider’s bite.

  • Ants’ stings as well as fleas’, bed bugs’, houseflies and beetles.
  • Different skin irritations.
  • Infections diseases, which are seen on skin.
  • Traumas.
  • Panic attack.
Almost all 30 000 species of spiders are venomous. But their mandibles are often too fragile or short to sting human skin. Nevertheless there are spiders, which can cause serious system reactions. Such spiders are brown recluses, wandering spiders and black widows.

Spiders’ bites can be lethally dangerous and just unpleasant. Most spiders work out venom that causes neurotoxin effect, which paralyze the victim’s nervous system.

Spider Bites

Spiders’ bites can be lethally dangerous and just unpleasant.

What does a spider bite look like? How to tell a simple scratch resulted in the gardening or travelling from the spiders’ bite?

  • Very often people don’t feel anything in the bite site or may describe it as piercing with a thin needle.
  • A small whitish spot on the bitten place with pink or red edges.
  • Sometimes the spider’s bite has two holes.
  • After 5-20 min the poison spreads with blood throughout the whole body, causing more significant symptoms:
  • Intense muscle pain, possible convulsion.
  • A face becomes red and may swell.
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Spider’s bites differ from each other due to their types.

  1. Tarantula spider’s bite looks like a little pale swelling with reddish edges. Within 1-2 hours the swell or blister transforms into a wound.
  2. Brown recluse’s bite is the same blister, surrounded by purple, white or red edges in irregular form. It is often called “target” or “bull’s eye”. The blister grows very fast and in a while bursts, leaving an open erosive wound. It is very dangerous firstly because the bitten human doesn’t’ feel any pain. All symptoms start in two days.
  3. Black widow’s bite is mostly invisible. It much resembles a bite from a flea or a mosquito. There is a microscopic spot of red color that quickly disappears. The typical symptoms appear after two hours.
  4. House spider’s bite. Its bites are really painful, but disappear soon without intoxication symptoms. Only sensible to spider’s toxin people may feel dizziness, vomiting and fever. Also there may be a tiny swell in the bitten place.


Tarantula spider’s bite looks like a little pale swelling with reddish edges.

Tarantula spider’s bite looks like a little pale swelling with reddish edges.

Symptoms of Spider Bites

The most dangerous effects resulting from spider’s bite are death of tissue, wound contamination and loxoscelism. These are typical symptoms of brown recluse’s bite. Loxoscelism is a tissue necrosis, which can be deepened till muscles and even bones. Also post-effects include lethally dangerous system syndrome (fever, diffuse myalgia, arthralgia, convulsion, quickly fall of blood pressure, erythrocyte lysis and heart problems).

The symptoms are fused into 3 groups:

Weak and not dangerous effects:

  • bearable pain in the bitten place,
  • dermahemia,
  • small swelling,
  • itching and burning feeling.
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Effects that can be felt during a week:

  • pain,
  • swell, tumor,
  • itching and rushing,
  • diarrhea,
  • local convulsion,
  • somnolence and general weakness.

Post-effects that are considered threatening:

  • sharp pain intensive spreading throughout the body,
  • quickly developing swell,
  • generalized convulsion,
  • diarrhea,
  • Somnambulism, weakness due to falling blood pressure,
  • Kidney failure.

The most dangerous effects resulting from spider’s bite are death of tissue.

Brown recluse spider bites have the following symptoms:

  • acute pain after 30-60 min after bite,
  • itching throughout the body,
  • central blister becomes larger, fills with blood, blows out leaving an erosive wound,
  • system syndrome after 24-72 hours after biting. All mortal cases are connected with the action of the syndrome.

There are also symptoms similar to other illnesses, though they demand to call a doctor:

  • Purple, blue blister with dots in white, then red circles. In toxicology this syndrome is widely known as “red, white, and blue”.
  • Rash on the whole body.
  • Muscles’ spasms, sometimes convulsions – both in legs and in arms.
  • Numbing feeling in the wound, it becomes hard.
  • Ache in the right side similar to appendicitis.
  • Growing headache and sharp fever.
  • General weakness.

Black Widow Spider Bites

In an hour limit intoxication can result in local pain, sweatiness, erythema. The pain may be either sharp or dull. System syndrome follows neurotoxin action of the venom and shows impulsion, sweatiness, rash, itch, swell in eye-lids and limbs, problems with breath, increasing temperature in the wounded area, painful spasms and stomachache as well as strain in shoulders, chest and back. Death is rather rare. In general, symptoms become lighter in 1-3 days, but convulsion, weakness and anxiety may last long enough, up to some weeks or even months.
Black Widow Spider Bites

Sweatiness, rash, itch, swell in eye-lids and limbs, problems with breath, increasing temperature in the wounded area, painful spasms and stomachache as well as strain in shoulders – the symptoms after bite.

Tarantula’s Bites

In humans tarantula’s bites cause hurt and pain. Throwing hairs leads to itching or even problems with breathing. Then the bite transforms into local swelling with rash around it. The human suffers from high temperature, headache, and general weakness. Death becomes rare and only if the bitten human has allergy to tarantula’s bites. Usually the wound disappears in 3-5 days.

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Brown recluse spider bites

Its bites are dangerous as they don’t cause any painful feelings. After 2 days there is hard itch and swell. Then the swelling leads to necrosis of tissues. Also it is followed by typical flu symptoms – fever, running nose, coughing and general weakness. In the case of hard intoxication, the venom interrupts kidney’s and heart’s work and cause to death.


After 2 days bites are hard itch and swell.

Diseases After Spiders’ Bites

The most horrible complications resulting from spiders’ bite may become local necrosis of skin and tissues. The necrosis may develop up to 10 cm in diameter. The situation is worsened by the danger of infectious contamination of the wound.

Meanwhile, there can be the following common symptoms:

  • continuous swelling of the hurt place,
  • muscle and bone pain,
  • convulsion readiness of the brain for a definite period of time,
  • kidney and liver’s failure,
  • thrombosis of the blood vessels,
  • bleeding in the intestine and stomach.

But some people have significant cases.

Skin Necrosis or Necrotizing Arachnidism

This syndrome is followed by painless stinging at first. Then the pain starts to accompany with local redness of skin and developing of a blister, after bursting resulting in an ulster. The erosive wound is rather deep and exposes muscle tissues

Skin Necrosis or Necrotizing Arachnidism

This is the Skin Necrosis.

Loxosceles Envenomation

It may end in life-dangerous blood contamination and death. It manifests with skin death, blister developing with further complex post-effects (kidney failure, problems with blood and vessels). The wound can be 25 cm in diameter; it heals up within 3-6 months and leaves a scar.


It is a system syndrome, caused by the black widow spider. It is followed be acute pain in muscles, weakness, vomiting, dizziness, and rich sweating. Unless being treated, the bitten people report continuous site pain during several weeks or even months. Death often occurs in children, the elderly and weakened people, especially those who have heart diseases as latrodectism worsens inflammation of the heart muscles.
dizziness and weakness

It is followed be acute pain in muscles, weakness, vomiting, dizziness, and rich sweating.

Allergic reactions

They are different and can resemble flu or cold symptoms with high temperature and sweating or can cause really lethal cases, such as anaphylaxis. Anaphylaxis is typical for throat swelling, which makes breathing difficult or even impossible. Other symptoms are the next:

  • tongue and lips swelling,
  • itching in the mouth and throat.

Mild cases of allergy to spider bites include swelling of the bite site, eyelids, and hands, hives’ development, which look like red itchy spots either in the local place or throughout the body. Allergy is dangerous because a lot of people don’t know about having it until they are bitten. The second bite of the same type of spider may cause much more complex and severe symptoms.

tongue and lips swelling

Tongue and lips swelling – symptoms of allergy.

Can Spider Bites Kill You?

Fortunately, most spiders are unable to kill humans, because of weak mandibles or little toxin concentration.

Nevertheless, there are spiders, which people should avoid to contact with. Many of them inhabit only southern and tropical regions, but may occur in Northern America.

One group of spiders causes death due to hemophilic reaction, others – by neurotoxin action. Here is a list of the most dangerous spiders in America:

  • Brazilian wandering spider. It is considered the most venomous one in the world. What is more, they are aggressive. They have very powerful neurotoxin, which leads to breathe problems.
  • Black widow spider. In spite of the fact that their venom is highly toxic, the bites rarely lead to humans’ death. Allergic reaction is an exception. That is because black widow spider injects little amount of poison into the human.
  • The brown recluse or violin spider. Its bites are really toxic and each case needs hospitalization. Even after healing, it leaves deep hives and scars.
  • Hobo spider is also medically significant as its bites are very venomous. Hobo’s stings need proper treatment for they may cause developing of a blister and then hives.
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