Table of ContentsView AllTable of ContentsWhat It IsCausesSymptomsTreatmentOther InfectionsAllergic ReactionsPreventionWhen to See a ProviderFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
What It Is
Causes
Symptoms
Treatment
Other Infections
Allergic Reactions
Prevention
When to See a Provider
Frequently Asked Questions
Bug and spider bites may need antibiotic treatment if they turn into a skin infection calledcellulitis. A bug or spider bite makes an open wound in the skin where bacteria can get in. This can lead to cellulitis, a serious medical problem that needs treatment as soon as possible.
This article will explain when bug and spider bites need antibiotics for cellulitis and what other treatment you may need if a bite gets infected.
Verywell / Jessica Olah
What Is Cellulitis?
Cellulitis is a skin infection that goes into deeper areas of the skin (subcutaneous tissue). It causes symptoms like redness, swelling, and tenderness in the affected area of the skin.
The most common cause of cellulitis is bacteria called group AStreptococcus.Staphylococcus aureuscan also cause cellulitis and usually causes a pus-like discharge from the infected wound.
Cellulitis can appear anywhere on the body but is most commonly found on the feet and legs. Since it is a deeper infection than other skin infections, it can involve more extensive areas of the skin.People can also develop fever, chills, and malaise with cellulitis.
Since bug bites happen on the skin, they can cause cellulitis. But cellulitis can also develop from other skin injuries like cuts, needle sticks, as well as wounds after surgery.People with chronic skin conditions (likeeczema) or brief illnesses that affect the skin (likeshingles) can also get cellulitis.
Some people are more at risk for getting cellulitis from a bug or spider bite, including those who:
If left untreated, cellulitis can spread to other parts of the body and can even be life-threatening. Oral antibiotics need to be taken as soon as possible to clear up the infection and prevent complications.
How Is Cellulitis Caused By a Bug Bite?
Most bug bites do not get infected or lead to cellulitis but it’s important to know about the risk. The bacteria that cause cellulitis do not come from the bug that bit you. Bug and spider bites make breaks in theskin; bacteria that often hang out on human bodies and are harmless can get into the body through the opening. Once inside, the bacteria can lead to an infection.
Bacteria like group AStreptococcusandStaphylococcus aureusare common in the environment and on your skin. If they get into your body through a bug or spider bite, you could develop cellulitis.
Scratching or picking at a bite can make an infection more likely since you are opening up the skin even more.
What Other Bug Bites Can Cause Cellulitis?FleasMosquitosTicksBedbugsFliesSpiders
What Other Bug Bites Can Cause Cellulitis?
FleasMosquitosTicksBedbugsFliesSpiders
What Are the Symptoms of Cellulitis From a Bug Bite?
Bug bite infection symptoms vary according to the type of infection and how bad it is, as well as which insect bit you. As bacteria multiply in the skin, symptoms of cellulitis start to show up. Cellulitis from a bug or spider bite can cause:
If you have a bad infection, the bite may have yellow drainage. Sometimes, the pus-like material collects under the skin to form a pocket (abscess). As the infection gets worse, other symptoms might develop likefatigue, chills, or afever.
Expert Advice on Dealing With Bug Bites on the Eyelid
How Is Cellulitis From a Bug Bite Treated?
Medical Treatments
You may need topical, oral, or intravenous (IV) antibiotics for a bug bite infection.
You may also need to take other medications to help with pain and swelling while you are waiting for antibiotics to work. For example, Tylenol (acetaminophen) is an effective over-the-counter (OTC) pain reliever. Ibuprofen can also treat pain as well as provide anti-inflammatory effects that can treat redness and swelling.
Is It MRSA?According to the Centers for Disease Control and Prevention, 33% of the population is colonized withStaphylococcus aureus(meaning they have the bacteria but without symptoms), but around 1% of people are colonized with methicillin-resistantStaphylococcus aureus(MRSA).
Is It MRSA?
According to the Centers for Disease Control and Prevention, 33% of the population is colonized withStaphylococcus aureus(meaning they have the bacteria but without symptoms), but around 1% of people are colonized with methicillin-resistantStaphylococcus aureus(MRSA).
Home Remedies
Natural remedies often claim to have wound-healing effects, but these remedies have not been proven to treat an infection in high-quality research studies.
If you have cellulitis from a bug or spider bite, you need medical treatment. In addition, your provider may also recommend some steps you can take at home to help your skin heal.
If you just have a minor infection, your provider might ask you to try OTCtopical antibiotic ointments, like bacitracin or triple antibiotic therapy. However, research has not shown any difference when using ointments instead of just using basic wound care to treat a minor skin infection.
What Antibiotics Treat Spider Bite Infections?
Theantibioticsfor cellulitis from a spider bite infection will depend on several factors, like the severity and what medication would be the safest and most effective. Your provider will also consider your risk of having an infection that is resistant to treatment.
Cephalexin, sulfamethoxazole-trimethoprim, or clindamycin are usually the choices of antibiotics that can treat cellulitis, including when it’s from a spider bite.
Additional Type of Bug Bites Infections
Bug bites can lead to other skin infections and complications from those infections, such as:
Less commonly, bug and spider bites can lead to:
Diagnosing Bug Bite InfectionsA healthcare provider can diagnose skin infections from bug and spider bites based on how they look. They might also ask about any other symptoms you’re having, like a fever.
Diagnosing Bug Bite Infections
A healthcare provider can diagnose skin infections from bug and spider bites based on how they look. They might also ask about any other symptoms you’re having, like a fever.
Impetigo
Treating impetigo usually does not require oral antibiotics. If it does, topical therapy is often all that is needed. A provider will most likely prescribe mupirocin or retapamulin.
Lymphangitis
Lymphangitisis a streaking redness that looks like it is spreading out from an infected bug bite with cellulitis.The streaking redness shows the spread of infection along a drainage system called the lymphatic system. The drainage moves toward thelymph nodesthat are helping fight the infection.
Lymphangitis is often associated with serious symptoms like fever, chills, muscle aches, and malaise. It generally means that cellulitis is getting worse and is spreading through the body.
Treatment should start right away. Sometimes, IV antibiotics are used instead of oral antibiotics. The same antibiotics that are used to treat cellulitis are used to treat lymphangitis, but it is more likely that a person will require IV treatment if they have an infection that is spreading.
Abscess
Anabscessis a collection of pus under the skin. If a bug or spider bite gets infected, the pus can build up and be walled off under the skin and form an abscess. It usually looks red and like a pimple, and can be painful or warm if you touch it.
An abscess is an infection that needs medical care. You may need to take antibiotics and a provider might have to open the abscess so it can drain. You should never try to “pop” or cut open an abscess on your own at home.
Folliculitis
An infected hair follicle is calledfolliculitis. It usually causes pus-filled bumps on the skin that can hurt. Folliculitis happens when hair follicles get blocked or damaged, like from too-tight clothes or a trauma. If a bug bite is near a hair follicle, it may irritate it.
Necrotizing Fasciitis
Necrotizing fasciitisis a serious skin infection that goes deep into the skin and tissues. Sometimes, it’s called “flesh-eating bacteria” because some forms of it cause the skin to die. It’s not common, but an infected insect or spider bite that is not treated could lead to necrotizing fasciitis.
If you develop this serious infection from a bug bite, you need medical treatment right away because it can spread very quickly, become very serious, and can even be fatal.
Erysipelas
Erysipelas can be treated with antibiotics and OTC pain relievers.
Spider BitesWhilespidersdo not carry diseases like ticks or mosquitos, some of them have venom or poison that can make humans sick if they’re bitten. For example, abite from a black widow spidercan be very painful and may cause other symptoms because the poisonous substance they transmit (neurotoxin) can affect the brain.
Spider Bites
Whilespidersdo not carry diseases like ticks or mosquitos, some of them have venom or poison that can make humans sick if they’re bitten. For example, abite from a black widow spidercan be very painful and may cause other symptoms because the poisonous substance they transmit (neurotoxin) can affect the brain.
Can You Be Allergic to Bug Bites?
Some bug bites that cause serious skin reactions could be anallergic reactionsrather than an infection. Rarely, allergic reactions to bug or spider bites are life-threatening.
Allergic reactions to insect saliva come on much faster than an infection. The skin will often swell a lot, and a person can gethives. The bitten area will also be itchy.
Treating an allergic reaction starts with ice and topical anti-itch creams, likehydrocortisoneorantihistamines. If the allergic reaction is severe, a person will need to see a provider for systemic steroid medication. If a person has anaphylaxis, they will need emergency medical care and an epinephrine shot.
Watch for AnaphylaxisIf the allergic reaction affects the entire body, it can lead to a life-threatening condition calledanaphylaxis. Symptoms of a more severe reaction after a bug bite occur soon after a person is bitten and include:DizzinessNausea and vomitingItching over the entire bodyWheezing and shortness of breathAs the allergic reaction gets worse, a person’s blood pressure starts to drop and they might pass out (lose consciousness). If not treated, they could go into cardiac arrest and may die.
Watch for Anaphylaxis
If the allergic reaction affects the entire body, it can lead to a life-threatening condition calledanaphylaxis. Symptoms of a more severe reaction after a bug bite occur soon after a person is bitten and include:DizzinessNausea and vomitingItching over the entire bodyWheezing and shortness of breathAs the allergic reaction gets worse, a person’s blood pressure starts to drop and they might pass out (lose consciousness). If not treated, they could go into cardiac arrest and may die.
If the allergic reaction affects the entire body, it can lead to a life-threatening condition calledanaphylaxis. Symptoms of a more severe reaction after a bug bite occur soon after a person is bitten and include:
As the allergic reaction gets worse, a person’s blood pressure starts to drop and they might pass out (lose consciousness). If not treated, they could go into cardiac arrest and may die.
The best way to prevent a bug or spider bite infection is to do what you can to avoid being bitten. Here are a few tips for preventing bug and spider bites:
Topical therapies like baking soda and water paste, hydrocortisone cream, or Benadryl cream can help with itching.
Remember, itching also breaks the skin, so avoiding scratching the area can prevent infection.
Research does not suggest that people need to prophylactically (preventatively) use topical antibiotics or take pills to prevent an infection. However, researchers do not agree on whether people who get frequent skin infections should use prophylactic antibiotics.
If you are someone who often gets a skin infection after a bug bite or another break in your skin, talk to your provider about whether you need prophylactic antibiotics.
When to See a Healthcare Provider
An infected bug bite usually needs antibiotic treatment. It can be hard to know if a bug or spider bite is swollen and red because of inflammation from your immune system’s normal response, or whether you have an infection.
Remember: An infection does not happen immediately, and can take time to develop after a bug bite. If the redness, swelling, and pain increase after cleaning and managing the wound at home, call your healthcare provider.
Summary
If you have cellulitis from a bug or spider bite, you will need to take antibiotics. Your provider will recommend the antibiotic that is safest and most effective for you to take.
Bug and spider bites do not usually get infected, but it’s important to know the signs of an infection and get medical treatment. You should also take steps to avoid bug and spider bites, whether you’re at home or enjoying the outdoors.
Frequently Asked QuestionsAn infected bug bite will start to improve two to three days after you begin taking antibiotics. Your healthcare provider will most likely prescribe seven days of treatment.Redness and swelling occur after bug bites. If the swelling quickly worsens, is associated with a rash elsewhere on the body, and causes intense itching, it’s probably an allergic reaction. However, if the swelling worsens over time and starts to hurt or show a yellow crust, it’s probably infected.
An infected bug bite will start to improve two to three days after you begin taking antibiotics. Your healthcare provider will most likely prescribe seven days of treatment.
Redness and swelling occur after bug bites. If the swelling quickly worsens, is associated with a rash elsewhere on the body, and causes intense itching, it’s probably an allergic reaction. However, if the swelling worsens over time and starts to hurt or show a yellow crust, it’s probably infected.
20 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Centers for Disease Control and Prevention.About cellulitis.Stevens DL, Bryant AE, University of Oklahoma Health Sciences Center.Impetigo, erysipelas and cellulitis.MedlinePlus.Cellulitis.Cleveland Clinic.Cellulitis from a bug bite.Centers for Disease Control and Prevention.MRSA and the workplace.Williamson DA, Carter GP, Howden BP.Current and emerging topical antibacterials and antiseptics: agents, action, and resistance patterns.Clin Microbiol Rev. 2017;30(3):827-860. doi:10.1128/CMR.00112-16Centers for Disease Control and Prevention.About impetigo.MedlinePlus.Lymphangitis.Children’s Health Partners.Boil/abscess/cellulitis.Penn Medicine.Folliculitis.American Academy of Dermatology Association.Acne-like breakouts could be folliculitis.Centers for Disease Control and Prevention.About ticks and tickborne diseases.Centers for Disease Control and Prevention.Other mosquito-borne diseases.Fernando DM, Kaluarachchi CI, Ratnatunga CN.Necrotizing fasciitis and death following an insect bite.Am J Forensic Med Pathol. 2013;34(3):234-236. doi:10.1097/PAF.0b013e3182a18b0bNORD.Necrotizing fasciitis.Bläckberg A, Trell K, Rasmussen M.Erysipelas, a large retrospective study of aetiology and clinical presentation. 2015;15(1). doi:10.1186/s12879-015-1134-2Brindle R, O. Martin Williams, Barton EJ, Featherstone PI.Assessment of antibiotic treatment of cellulitis and erysipelas. 2019;155(9):1033-1033. doi:10.1001/jamadermatol.2019.0884University of Rochester Medical Center.When spiders bite.Institute for Quality and Efficiency in Health Care.Insect venom allergies: overview.Centers for Disease Control and Prevention.About mosquito bites.
20 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Centers for Disease Control and Prevention.About cellulitis.Stevens DL, Bryant AE, University of Oklahoma Health Sciences Center.Impetigo, erysipelas and cellulitis.MedlinePlus.Cellulitis.Cleveland Clinic.Cellulitis from a bug bite.Centers for Disease Control and Prevention.MRSA and the workplace.Williamson DA, Carter GP, Howden BP.Current and emerging topical antibacterials and antiseptics: agents, action, and resistance patterns.Clin Microbiol Rev. 2017;30(3):827-860. doi:10.1128/CMR.00112-16Centers for Disease Control and Prevention.About impetigo.MedlinePlus.Lymphangitis.Children’s Health Partners.Boil/abscess/cellulitis.Penn Medicine.Folliculitis.American Academy of Dermatology Association.Acne-like breakouts could be folliculitis.Centers for Disease Control and Prevention.About ticks and tickborne diseases.Centers for Disease Control and Prevention.Other mosquito-borne diseases.Fernando DM, Kaluarachchi CI, Ratnatunga CN.Necrotizing fasciitis and death following an insect bite.Am J Forensic Med Pathol. 2013;34(3):234-236. doi:10.1097/PAF.0b013e3182a18b0bNORD.Necrotizing fasciitis.Bläckberg A, Trell K, Rasmussen M.Erysipelas, a large retrospective study of aetiology and clinical presentation. 2015;15(1). doi:10.1186/s12879-015-1134-2Brindle R, O. Martin Williams, Barton EJ, Featherstone PI.Assessment of antibiotic treatment of cellulitis and erysipelas. 2019;155(9):1033-1033. doi:10.1001/jamadermatol.2019.0884University of Rochester Medical Center.When spiders bite.Institute for Quality and Efficiency in Health Care.Insect venom allergies: overview.Centers for Disease Control and Prevention.About mosquito bites.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Centers for Disease Control and Prevention.About cellulitis.Stevens DL, Bryant AE, University of Oklahoma Health Sciences Center.Impetigo, erysipelas and cellulitis.MedlinePlus.Cellulitis.Cleveland Clinic.Cellulitis from a bug bite.Centers for Disease Control and Prevention.MRSA and the workplace.Williamson DA, Carter GP, Howden BP.Current and emerging topical antibacterials and antiseptics: agents, action, and resistance patterns.Clin Microbiol Rev. 2017;30(3):827-860. doi:10.1128/CMR.00112-16Centers for Disease Control and Prevention.About impetigo.MedlinePlus.Lymphangitis.Children’s Health Partners.Boil/abscess/cellulitis.Penn Medicine.Folliculitis.American Academy of Dermatology Association.Acne-like breakouts could be folliculitis.Centers for Disease Control and Prevention.About ticks and tickborne diseases.Centers for Disease Control and Prevention.Other mosquito-borne diseases.Fernando DM, Kaluarachchi CI, Ratnatunga CN.Necrotizing fasciitis and death following an insect bite.Am J Forensic Med Pathol. 2013;34(3):234-236. doi:10.1097/PAF.0b013e3182a18b0bNORD.Necrotizing fasciitis.Bläckberg A, Trell K, Rasmussen M.Erysipelas, a large retrospective study of aetiology and clinical presentation. 2015;15(1). doi:10.1186/s12879-015-1134-2Brindle R, O. Martin Williams, Barton EJ, Featherstone PI.Assessment of antibiotic treatment of cellulitis and erysipelas. 2019;155(9):1033-1033. doi:10.1001/jamadermatol.2019.0884University of Rochester Medical Center.When spiders bite.Institute for Quality and Efficiency in Health Care.Insect venom allergies: overview.Centers for Disease Control and Prevention.About mosquito bites.
Centers for Disease Control and Prevention.About cellulitis.
Stevens DL, Bryant AE, University of Oklahoma Health Sciences Center.Impetigo, erysipelas and cellulitis.
MedlinePlus.Cellulitis.
Cleveland Clinic.Cellulitis from a bug bite.
Centers for Disease Control and Prevention.MRSA and the workplace.
Williamson DA, Carter GP, Howden BP.Current and emerging topical antibacterials and antiseptics: agents, action, and resistance patterns.Clin Microbiol Rev. 2017;30(3):827-860. doi:10.1128/CMR.00112-16
Centers for Disease Control and Prevention.About impetigo.
MedlinePlus.Lymphangitis.
Children’s Health Partners.Boil/abscess/cellulitis.
Penn Medicine.Folliculitis.
American Academy of Dermatology Association.Acne-like breakouts could be folliculitis.
Centers for Disease Control and Prevention.About ticks and tickborne diseases.
Centers for Disease Control and Prevention.Other mosquito-borne diseases.
Fernando DM, Kaluarachchi CI, Ratnatunga CN.Necrotizing fasciitis and death following an insect bite.Am J Forensic Med Pathol. 2013;34(3):234-236. doi:10.1097/PAF.0b013e3182a18b0b
NORD.Necrotizing fasciitis.
Bläckberg A, Trell K, Rasmussen M.Erysipelas, a large retrospective study of aetiology and clinical presentation. 2015;15(1). doi:10.1186/s12879-015-1134-2
Brindle R, O. Martin Williams, Barton EJ, Featherstone PI.Assessment of antibiotic treatment of cellulitis and erysipelas. 2019;155(9):1033-1033. doi:10.1001/jamadermatol.2019.0884
University of Rochester Medical Center.When spiders bite.
Institute for Quality and Efficiency in Health Care.Insect venom allergies: overview.
Centers for Disease Control and Prevention.About mosquito bites.
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