What Does a Bruise from a Spider Bite Look Like?
Bruising is one of the most common symptoms of a spider bite. The area around the bite will often turn reddish-blue or purple as blood pools under the skin. This bruising may start out small - just around the actual bite - but can spread over hours or days to cover a larger area of the arm, leg or body where you were bitten.
The size of the bruise can give clues as to whether the spider bite is from a dangerous spider like a black widow or brown recluse. Black widow bites usually result in pinpoint bruising with a small puncture wound in the middle. Brown recluse spider bites often cause more localized bruising that spreads across 6 inches or more of skin.
Some people may also experience swelling around a spider bite as the tissues become inflamed. The swelling and bruising together can cause the bite to resemble a bull's eye with a central darkened puncture wound and reddish outer ring as blood spreads under the skin.
What Causes Bruising After a Spider Bite?
Bruising and swelling after a spider bite are caused by the spider's venom, which contains molecules that damage tissues and blood vessels under the skin. Some spider venoms also contain chemicals that prevent blood from clotting properly.
The venom triggers the body's inflammatory response, causing blood and other fluids to leak out of damaged capillaries and into the surrounding tissues. This causes redness and swelling. As the blood pools and spreads, it turns a bruise-like purple or blue color before slowly being reabsorbed into the body.
Certain spiders like the brown recluse have venoms that break down cell membranes and tissues. This can cause localized skin damage and widespread bruising by allowing blood to leak out of blood vessels over a larger area.
Do All Spider Bites Cause Bruises?
While bruising is very common after a spider bite, not all spider bites will lead to bruising. Some people may only experience redness, itching, swelling or pains at the bite site without obvious discoloration of the skin.
Spider bites that don't cause bruising may come from less venomous varieties like grass spiders, wolf spiders, or jumping spiders. The mild irritant effects of their venom lead to localized redness and itching rather than extensive tissue damage and bleeding.
Young children and the elderly are more vulnerable to bruising from spider bites, even from less dangerous spider species. Their capillaries and blood vessels are more fragile and likely to break and bleed even from mild trauma.
Identifying Spider Bites by Type of Bruise
While all spider bites can potentially cause some bruising, the size, appearance and distribution of the bruising can help identify what species was responsible for the bite.
Black Widow Spider Bites
Black widow spider bites usually cause a small pinpoint bruise with a red puncture wound in the center. The bite mark may be surrounded by a wide area of swelling. The bruise usually doesn't grow larger than an inch or two across.
There are a few different species of black widow spiders in North America that can produce bites with similar bruising patterns including the southern, northern and western widows.
Brown Recluse Spider Bites
Brown recluse spider bites often cause more intense bruising that spreads across a larger area of skin. The bruise frequently grows over hours and days to cover 6 inches or more. The middle of the bruise is often dark purple, black or blue with patchy outer edges.
This widespread bruising is caused by the brown recluse's tissue destroying venom. The venom causes cellular breakdown and extensive capillary damage allowing blood to widely leak from vessels under the skin.
Hobo Spider Bites
The hobo spider is found across the northwestern United States. Bites cause mild pain, redness and bruising around the puncture site. The bruise may spread a few inches across and is often accompanied by a hive-like rash.
Hobo spider bites don't cause the severe skin necrosis seen with brown recluse bites. But they can still be mistaken for recluse bites due to moderate localized bruising.
Tarantula Bites
Most tarantulas found in the U.S. have relatively mild venom and bites rarely cause severe reactions beyond local pain and swelling. However, the Poecilotheria genus of ornamental tarantulas can produce worse effects when they bite. Their bites often result in intense stinging pain followed by bruising over the next few days.
If there is intense, spreading bruising around the bite of a pet spider, it's a good idea to call a poison control center for evaluation, even if the species is not normally dangerous.
Treatment for Bruising from Spider Bites
Most spider bite bruises will heal on their own like any normal bruise. The pooled blood is slowly reabsorbed and metabolized. However, there are a few things you can do at home to help speed healing and reduce discomfort:
Ice Packs
Applying ice to a spider bite helps reduce swelling and inflammation. This can limit the extent of bruising by constricting blood vessels to reduce internal bleeding. Ice also helps numb the area to relieve pain.
Elevation
Keeping the bitten limb elevated above heart level uses gravity to reduce blood pooling in the tissues. This takes pressure off damaged capillaries to limit bruising.
OTC Pain Relievers
Over-the-counter drugs like acetaminophen (Tylenol), ibuprofen (Advil) or naproxen (Aleve) can help relieve aches from the bite while also reducing swelling.
Antihistamines
Taking antihistamines like diphenhydramine or loratadine will relieve itching and allergic reactions. They also help decrease localized inflammation and swelling.
Warm Compresses
Applying a warm, wet washcloth to the bite can help increase blood flow to reabsorb the pooled blood in a bruise. Repeat for 20 minutes a few times a day.
Bruise Creams
There are some topical creams containing ingredients like arnica that may help reduce bruising. However, their effectiveness is debated.
Time
Most bruises from spider bites will fully resolve within 1-2 weeks as the body reabsorbs the trapped blood. The bruise will change color from blue to green to yellow as it heals.
When to See a Doctor for Spider Bite Bruising
In most cases, bruising from a spider bite will be limited to the area around the bite and gradually improve with home care. However, there are some situations when you should seek medical care:
- The bruise is spreading over a wide area.
- You develop flu-like symptoms like fever, rash or muscle pains.
- The bite area feels numb or detached from the body.
- You notice pus, increasing warmth or red streaking from the bite.
- Your pain becomes severe or doesn't improve with over-the-counter medicine.
- You have a compromised immune system that makes infections more serious.
Extensive, spreading bruising or bruising along with systemic symptoms can signal a serious reaction to a venomous spider bite. Seek emergency care if you experience difficulty breathing, excessive vomiting, seizure or loss of consciousness after a bite.
Preventing Spider Bites and Bruising
You can reduce your chances of spider bites and associated bruising by taking these preventative measures:
- Wear gloves, long sleeves and pants when cleaning storage areas, garages or basements where spiders live.
- Clear clutter and debris from your home to minimize dark hiding spots appealing to spiders.
- Seal cracks and crevices around windows and doors to block spider entry points.
- Inspect or shake out clothing, towels and shoes before use to dislodge any hidden spiders.
- Keep beds pulled away from walls and tuck in sheets to prevent bites at night.
- Apply insecticides around baseboards, windows and doorways to deter spiders.
- Install yellow bug lights that are less attractive to insects that spiders prey on.
- Be careful handling firewood and leaves where spiders may hide.
While most spider bites are harmless, getting bitten by certain venomous spiders can definitely cause varying degrees of bruising. Being able to identify a spider bite bruise and watching for spreading discoloration or systemic symptoms allows prompt treatment for any significant envenomation.
FAQs
What does a spider bite bruise look like?
Spider bite bruises often appear as a reddish, purple or blue discoloration around the bite. The area may swell up and the bruise can spread over hours or days. Bites from spiders like black widows cause localized pinpoint bruising while brown recluse bites result in more widespread bruising.
Do all spider bites cause bruises?
No, some spider bites may just cause redness, itching or swelling without bruising. Less venomous species like grass spiders usually don't cause heavy bruising. However, bites from spiders like black widows, brown recluses and hobo spiders often do result in noticeable bruising.
How can you identify the type of spider by the bite bruise?
Black widow bites cause small, pinpoint bruises with central punctures. Brown recluse spider bites lead to larger spreading bruises over 6 inches or more. Hobo spiders cause mild bruising a few inches across. Tarantula bites can also cause intense bruising if they are highly venomous species.
How do you treat a spider bite bruise?
Applying ice, elevating the area, and OTC painkillers can help reduce swelling and discomfort from a spider bite bruise. Antihistamines alleviate itching. Warm compresses help encourage blood reabsorption. Most bruises disappear on their own within 1-2 weeks.
When should you seek medical care for a spider bite bruise?
See your doctor if the bruise spreads extensively, you develop flu-like symptoms, or you have severe pain, numbness, pus or red streaking. Also seek medical care if symptoms don't improve with self-care, or you have a compromised immune system.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.
Add Comment