What You Should Know About a Bug Bite Bruise

You probably don’t think of bruising when it comes to bug bites. Red marks, welts, and itching are the most common symptoms of insect bites. However, bites from bugs like spiders, hornets, wasps, mosquitos, and ticks may cause bruising.

This article explains bug bites that can leave a bruise, bug bite symptoms, treatment, and possible complications.

Child's legs with bruises and bug bites

sarune zurba / Getty Images

What Kind of Bug Bite Leaves a Bruise?

Various insects can leave behind a bruise after they bite. Sometimes, this reaction is from the injury; other times, it merely appears bruised as the bug bite darkens. 


It is not typical for non-venomous spiders to leave a bruise after biting. However, if you are bitten by a venomous spider, like a black widow or a brown recluse, the bite site may turn from red to purple.

In addition to a bruised appearance, other symptoms of a venomous spider bite include:

  • Itching
  • Pain
  • Sweating 
  • Trouble breathing
  • Headache
  • Nausea or vomiting
  • Fever, chills
  • Anxiety
  • Hypertension (high blood pressure)

Venomous spider bites require immediate medical attention.


Bee stings—especially those from hornets and wasps—are painful. While not a primary symptom of a sting, a bruise may occur around the sting due to the injury. 

Other symptoms of hornet and wasp stings include:

  • Pain
  • Redness
  • Swelling
  • Itching

Allergic Reactions

Signs of an allergic reaction include flushing, hives, dizziness, trouble breathing, and loss of consciousness.


Mosquitos are well known for their red welts and itching. But, bruising can also occur, especially in people with a mosquito allergy, known as “skeeter syndrome." Skeeter syndrome is not typically a life-threatening allergy.

Other symptoms include:

  • Large areas of swelling
  • Heat
  • Redness
  • Itching

Skeeter syndrome usually improves in a couple of days. If your symptoms worsen or last longer, seek medical attention for a possible skin infection.


Tick bites are painless, which is why it’s essential to check your body after time outdoors in tick-infested areas. When a tick embeds in your skin, the site may appear red or purple. 

After the bite, a skin rash is common, especially in the case of a tick-borne illness. The rash can look like a bullseye and is often pink or red, but it can be darker in color, too.

Other symptoms of a tick-borne illness include:

  • Fever
  • Chills
  • Headache
  • Fatigue
  • Muscle aches

Be aware that tick-borne illness symptoms can take up to a few weeks to develop. If you experience any of the above symptoms after you’ve spent time outdoors, speak to a healthcare provider.

If a bruise is accompanied by allergy or poisoning symptoms, like difficulty breathing, wheezing, nausea, or confusion, seek medical attention immediately.

Other Symptoms of Bug Bites

Bug bite symptoms vary; however, they often share some common traits. These include:

  • Redness
  • Welts
  • Hives
  • Pain
  • Itching

What Is Anaphylaxis?

Anaphylaxis is a life-threatening allergic reaction that requires immediate medical attention. Symptoms include:

  • Itching
  • Wheezing
  • Shortness of breath
  • Confusion

Causes of Bug Bite Bruises

Often the cause of purple skin around a bug bite is your body’s reaction to the saliva or venom from the insect. For example, when a mosquito sucks your blood, it injects saliva into your skin. This fluid exchange produces an itchy rash in most people, and it can also lead to a bruised appearance.

Other times, like with a bee sting or spider bite, when the venom releases into the skin and surrounding tissue, it causes pain and inflammation. These reactions can sometimes lead to bruising. 

Some insect vectors (those responsible for spreading human disease), like ticks, may cause a rash that appears purple. These rashes are unlike other bug bite reactions because they indicate a systemic (body-wide) infection rather than a localized skin reaction.


Usually, bug bites are a minor nuisance, but sometimes they can be more concerning. Therefore, the first step in treating a bug bite is identifying the culprit since this may determine the actions you take.

If you have a non-venomous, allergic, or infectious bite, the following is recommended:

In addition, take preventative measures to avoid insect bites by using insect repellent with DEET when spending time outdoors and keep your skin covered with clothing.

Complications of Bug Bites

Complications from bug bites include allergic reactions, skin infections, poisoning, and necrosis (skin and tissue death).     


Allergies to stings and bug bites require immediate medical attention. Signs of an allergic reaction include:

  • Flushing
  • Hives
  • Swelling
  • Dizziness
  • Trouble breathing
  • Nausea
  • Loss of consciousness
  • Shock

Around 15% of fatalities from anaphylaxis (severe allergic reaction) are from venom allergies.

Skin Infections

Since bug bites break the skin, they can lead to an infection. Symptoms of a skin infection include:

  • Rash
  • Swelling
  • Redness
  • Pain
  • Pus
  • Itching


Necrosis is when an infection results in the death of skin and surrounding tissues. This kind of infection is more likely with venomous spiders. Necrotizing infections are dangerous and require immediate medical attention. Symptoms include:

  • Swelling
  • Blisters
  • Skin that turns violet or black
  • High fever
  • Rapid heart rate
  • Confusion
  • Unconsciousness


Not all spider bites can make you sick, but some can. Symptoms of a venomous bite include:

  • Pain
  • Swelling
  • Necrosis
  • Fever
  • Trouble breathing

Seek medical attention immediately if you experience the above symptoms following a spider bite.


Some bug bites can cause a bruise or a bruised-like appearance. Insects that may cause bruising include mosquitos, ticks, bees, and spiders. Often a bruise isn't a cause for alarm, but keep an eye out for allergy symptoms, skin infections, necrosis, and more after an insect bite or sting. If any of these warning symptoms accompany your bug bite bruise, seek medical attention right away.

A Word From Verywell

Most of the time, bug bites are nothing but a minor nuisance. However, sometimes they can be more concerning. If you've been bitten or stung, keep an eye out for concerning symptoms. If you aren't sure whether to be concerned, it's best to err on the side of caution and seek medical advice.

Frequently Asked Questions

  • Is it dangerous if a bug bite turns purple?

    It's not necessarily dangerous if a bug bite turns purple. Sometimes, bug bites can bruise from the injury. However, in some cases, it can be cause for concern, because it can be a sign of necrosis (skin and tissue death). If purple skin is accompanied by infection or allergy symptoms, seek medical attention.

  • How do you identify a spider bite?

    Identifying the type of insect that bit you is not always straightforward. However, some things can offer clues. For example, if you were bitten inside, and the bite is painful, it may have been a spider. If the spider was venomous, you might notice further symptoms, like swelling, necrosis, fever, or trouble breathing.

  • Can mosquitos bite through clothes?

    Yes, mosquitos can bite through clothing. While covering exposed skin is a good precaution, using insect repellent is also a good idea.

13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Symptoms of venomous spider bites.  

  2. Johns Hopkins Medicine. Insect stings.

  3. Dhami S, Zaman H, Varga E, et al. Allergen immunotherapy for insect venom allergy: a systematic review and meta-analysis. Allergy. 2017;72(3):342-365. doi:10.1111/all.13077

  4. The American Academy of Allergy, Asthma & Immunology. Skeeter syndrome defined.

  5. Centers for Disease Control and Prevention. Symptoms of tick-borne illness.

  6. Seattle Children’s Hospital. Insect bite

  7. Centers for Disease Control and Prevention. Mosquito bite symptoms and treatment

  8. Children’s Hospital of Philadelphia. Bee and wasp stings.

  9. American Academy of Dermatology Association. Tips to prevent and treat bug bites.

  10. Jerschow E, Lin RY, Scaperotti MM, McGinn AP. Fatal anaphylaxis in the United States, 1999-2010: temporal patterns and demographic associations. J Allergy Clin Immunol. 2014;134(6):1318-1328.e7.

  11. National Library of Medicine. Skin infections

  12. Johns Hopkins Medical. What is necrotizing soft tissue infection?

  13. Rahmani F, Banan Khojasteh SM, Ebrahimi Bakhtavar H, Rahmani F, Shahsavari Nia K, Faridaalaee G. Poisonous spiders: bites, symptoms, and treatment; an educational reviewEmerg (Tehran). 2014;2(2):54-58.

By Kathi Valeii
As a freelance writer, Kathi has experience writing both reported features and essays for national publications on the topics of healthcare, advocacy, and education. The bulk of her work centers on parenting, education, health, and social justice.