Bites & Stings

  • Few things cause as much fear and anxiety in people as the thought of venomous spiders. Tennessee is home to many species of spiders; however, only two are venomous - the black widow and the brown recluse. Both species are found in every Tennessee county.

    Below are some useful tips for keeping spiders at bay:

    • Store clothing in sealed plastic bags or storage boxes
    • Store shoes in plastic shoe boxes
    • Shake clothing and shoes before wearing
    • Move beds away from walls or curtains
    • Remove bed skirts from box springs
    • Do not use bedspreads that touch or come close to the floor
    • Inspect bedding before climbing into bed
    • Consider keeping closet doors open to let in light
    • Move firewood away from the home, elevate it off the ground and cover it with plastic
    • Keep all vegetation and mulch at least 18 inches from the foundation of your home
    • Trim branches and shrubs away from the home to prevent spiders from using them as a path into the home
    • Seal all cracks and crevices where spiders may enter the home

    If you suspect that you have a spider bite, contact your primary care physician.

    The above information is provided by the University of Tennessee Agricultural Extension Service. For more information about spiders and other subjects, visit the Agricultural Extension Service website.

    Brown Recluse Spider


    The brown recluse is a shy, retiring spider that does not attack people and usually only bites in response to being injured. This is quite the opposite of what most people think! Most reported bites occur when putting on clothing in which the spider is hiding or rolling on a spider in bed. Most people living in proximity to the spider will never see it, nor be bitten by it.

    The brown recluse is a medium-sized spider. The legs span an area roughly the size of a quarter to a half-dollar. The color of the brown recluse ranges from a light yellowish brown to a dark reddish or chocolate brown, but most are light to medium brown. The second pair of legs is always longer than the remaining pair in both the male and female. Three pairs of eyes are arranged in a semicircle. Since most other spiders have eight eyes, this feature alone can eliminate many specimens suspected of being a brown recluse spider.

    The most distinguishing characteristic is the violin-shaped marking on the top of the body directly above the legs. The violin-shaped marking is usually much darker than the surrounding areas and may appear lined. Since some other species of spider have a violin-shaped marking, the best identification feature for the brown recluse is a semicircular arrangement of the three pairs of eyes. Contact your county Extension agent to identify a suspected brown recluse spider.


    Brown recluse spiders prefer sheltered areas with low moisture levels. In homes, they tend to prefer darkened storage areas in closets, garages, basements, attics and cupboards. Since most brown recluse spiders hibernate in the winter (except for those that live indoors), most bites occur between March and October when humans accidentally disturb their habitat: closets, out-buildings or woodpiles.

    For a photo and a publication on the brown recluse spider, click here.

    Black Widow Spider


    Black widow spiders are very numerous in nearly all parts of the U.S., but cases of reported bites are not common. For the most part, black widows live peacefully in close proximity to humans with little contact. Both the northern and southern black widows are found in Tennessee, with the southern species being the most common. The black widow appears shiny and hairless to the naked eye. The body ranges from a deep glossy black to an occasional dark brown to a reddish brown. The underside of the abdomen has a distinct red or orange hourglass shape. In immature spiders, the color can vary, and the hourglass may be white or missing.

    The body of the female adult black widow spider can reach 1 ½ inches with the legs fully extended. Black widow spiders have eight eyes arranged in two rows of four. The males are generally considered harmless and are usually about half the size of females with yellow or red spots or bands on the back or sides.


    The black widows prefer closed, dark places such as water meter compartments and crawl spaces, so barriers constructed to inhibit entrance to these areas are of value. Common places where black widow spiders may be found are firewood piles, under boards and furniture, inside boxes, behind and under debris, sheds, barns, well houses and root cellars.

    For a photo and a publication on the black widow spider, click here.

  • Even though Tennessee is landlocked, the Tennessee Poison Center (TPC) occasionally receives calls about envenomation's or poisonings from marine sources.

    IionfishI have this pet...

    The TPC received a call from an outpatient site regarding a patient who had a sting from his lionfish.

    Lionfish are a salt water fish that are commonly imported from the Philippines. Lionfish are in the Scorpaenidae family of vertebrate fish. The scorpionfish are divided into three genera depending on the venom organ structure. The genera are Pterosis (lionfish, turkeyfish, etc), Scorpaena (scorpion fish, etc) and Synanceja (stonefish). Pterosis have long slender spines as noted in the picture above left. The venom gland is covered by a thin integumentary sheath. Scorpaena have heavier spines with a thick integumentary sheath. Stonefish (Synanceja) have short thick spines with well-developed venom glands.  Stonefish are very well camouflaged in their native environment as noted in the picture to the right where it is difficult to find the stonefish. Scorpaenidae are usually bottom dwellers and inhabit shallow waters around coral reefs and kelp beds in the warm waters of the South Pacific.

    StonefishLionfish are popular as a salt water aquarium inhabitant as they have a distinctive and graceful appearance. Captive lionfish are venomous, and they can move quickly to envenomate. The envenomation occurs via the dorsal, anal, or pelvic spines that pierce into the skin. Envenomation's from lionfish that have recently died have also been reported. (JAMA 1985;253:807-810) The most common exposure is on the hands and fingers while the owner is trying to clean the aquarium or transfer the live specimen to another aquarium. Occasionally the envenomation occurs when the owner is trying to hand-feed the fish.

    “It floats like a butterfly, but stings like a bee”.  

    Symptoms from envenomation include severe and intense pain at the wound site with about half of the cases developing swelling. Systemic effects may include nausea, diaphoresis, difficulty breathing, hypotension, and syncope. The venom is poorly characterized, is heat labile, and is not dialyzable.  Recommendations for treatment include

    • soaking the affected area in non-scalding hot water (approximately 45oC)
    • wound care and pain management
    • administration of tetanus prophylaxis as needed. 

    NOAA mapInterestingly, there are sightings of Lionfish along the Southeastern coast of the United States (see map for locations in year 2003, map is from website of National Oceanic and Atmospheric Administration).  The source of the lionfish may be from the aquarium trade and less likely from the release of ballast water by ships. The impact of these non-native fish in this ecosystem is uncertain.

    National Oceanic and Atmospheric Administration, 2003

  • Reference: Swanson DL, Vetter RS. Bites of brown recluse spiders and suspected necrotic arachnidism . N Engl J Med 2005;352:700-7.

    Highlight: This review describes the epidemiology of Loxosceles spiders. It also provides a discussion of the frequency and types of misdiagnosis of acute arachnidism in areas where the Loxosceles spider does not reside.

    Reference: Vetter RS. Arachnids submitted as suspected brown recluse spiders (Araneae: Sicariidae): Loxosceles spiders are virtually restricted to their known distributions but are perceived to exist throughout the United States. J Med Entomol 2005;42:512-21.

    Highlight: Richard Vetter is in the Department of Entomology at University of California, Riverside. He made an internet offer to identify any spider that was thought to be a brown recluse spider in the United States. A total of 1773 arachnids were submitted from 49 states. Of these, only 324 were actually brown recluse spiders. These spiders were submitted from areas of the United States known to have endemic brown recluse spiders. In the end, brown recluse spiders have limited ability to disperse beyond their usual boundaries.  

    Reference: Furbeee RB, Kao LW, Ibrahim D. Brown recluse spider envenomation. Clin Lab Med 2006;26: 211-26.

    Highlight: This article has a summary discussion on the mechanism of the loxosceles venom. It also includes a table of the case reports of brown recluse spider envenomation’s. Interesting that 92% percent of these cases had no confirmation of a brown recluse spider.

  • Included are some newsletters and reviews on toxicology issues that Tennessee health professionals might find useful. The topic is Venomous Snakes in Tennessee:

    Venomous Snakes of Tennessee

    Death from a snake envenomation in North America is quite rare.

    Snake 101

    viperids All viperids have hinged fangs that are solenoglyphous (hollow). These fangs can rotate back and forth. When the mouth is closed, the fangs fold back against the roof of the mouth and are enclosed in a membranous sheath. The left and right fang can be rotated together or independently. If a tooth is lost, it is replaced, similar to a shark’s mouth.

    When a snake strikes, the speed is lightning fast. The mouth of the snake is nearly at an 180o angle as the target is approached. The generally accepted distance for striking is half the length of the snake. Most bites are defensive due to the snake trying to defend itself or being startled. Snakes have no interest in striking humans. Many times, a warning rattle is not heard since the snake was startled. The Agkistrodon species do not even possess a rattle. Up to 20-25% of snakebites are “dry” bites, meaning that no venom is actually injected.

    Venomous snake species in Tennessee

    A. contortrix, photo courtesy of Dr. Ian Jones The most common envenomation in Tennessee is from the copperhead snake (Agkistrodon contortrix). Fortunately, these envenomation's tend to be limited to tissue toxicity and most of these envenomation's do not require antivenom. Tennessee is also home to the cottonmouth (Agkistrodon piscivorus) whose name is derived from the behavior of opening its mouth to show the snowy white buccal mucosa. Tennessee is also the territory of the Timber rattlesnake, Crotalus horridus. Envenomation's from the Timber rattlesnake can be quite severe and present with cytotoxicity, hematotoxicity, and neurotoxicity. In addition, there is a Western Pigmy rattlesnake (Sistrurus miliarius) that resides in Tennessee, but this species is rarely involved in envenomation's. The Eastern Diamondback Rattlesnake (Crotalus adamanteus) is not usually found in Tennessee. Their range is along the coastal areas of southeastern North Carolina extending to Florida and Louisiana. A. contortrix, photo courtesy of Dr. Ian Jones.

    Initial measures after snakebite

    • Remove victim from the vicinity of the snake
    • Immediately remove any jewelry, watches, or rings from the affected extremity
    • If the bite is on an extremity, immobilize it.
    • Transport to the hospital.

    C. adamanteous, photo courtesy of Dr. Ian Jones
    C. adamanteous, photo courtesy of Dr. Ian Jones

    What to avoid doing in the setting of a North American snakebite

    • No ice
    • No electrical shock
    • No ligatures or tourniquets
    • No cutting or sucking on the wound

    At the hospital

    • If there is a bite to the face with swelling, secure the airway immediately
    • Assure that all jewelry, watches, rings are removed from the affected extremity
    • Assess degree of cytotoxicity, hematoxicity, and neurotoxicity
    • Elevate affected area
    • Contact the Tennessee Poison Center regarding indications for antivenom (1-800-222-1222)
  • In the South, tick borne illnesses are in season during the summer months.

    Rocky Mountain Spotted Fever (RMSF), Southern Tick-Associated Rash Illness (STARI), and Ehrlichiosis are endemic here in TN while Lyme disease is not.

    Reducing exposure to these biting arachnids is key. Check yourself and your children each day after being outdoors. This can be particularly difficult on the scalp when the child has long or thick hair. It may be easier to “feel” the tick on the scalp with my fingertips than see them. Don’t forget the areas such as the groin and the backside which may not be as easily visible. If you find an attached tick, remove with fine-tipped tweezers. Click here to learn how to remove a tick.

    Using an insect repellent such as DEET may be helpful for ticks but probably works better on those pesky mosquitoes. DEET can be applied directly to the skin as directed on the product label instructions with the following considerations for young children:

    • Not recommended for children under 2 months of age
    • Don’t apply to children’s hands. Don’t spray directly onto children’s faces and don’t apply around the eyes or mouth
    • Children 6 months to 2 years should be limited to one application per day
    • Children 2-12 years should be limited to 3 applications per day

    The maximum concentration used should be 10% or less for children up to 12 years of age.  These low concentrations are effective for 2-3 hours. A second application of DEET may be warranted if the child is out of doors for more than 12 hours. After returning indoors, wash the skin with soap and water.

    Permethrin is another available product that is used as an insecticide, acaricide (kills ticks and mites), and also considered an insect repellant. Permethrin is a synthetic derivative of natural pyrethrin which comes from chrysanthemums. Permethrin is applied to clothing, mosquito netting, etc., but not the skin when used for this purpose. While topical permethrin has an incredible safety profile in most mammals including humans, it should never be used on cats and is also very toxic to fish.

  •                      Toxicology Question of the Week

                                                                   March 12, 2018


    Indications for Crofab include: systemic symptoms, coagulopathy , and progression of swelling.  Most of the snakes in our state cause swelling as opposed to coagulopathy or systemic symptoms (although of course some do).  First aid includes elevation of extremity.  Progression of swelling means that swelling is progressing and the distal part of the extremity is not decreasing in size, as would occur with gravity, i.e. the swelling decreases distally and increases proximally (which is what you want).  Call the TN Poison Center to discuss indications for Crofab.  ds


    Who Am I and How Did I die?

    I’m a person from ancient days.

    Infamous for my worldly ways.

    Legends abound about my life.

    One claims I was my brother’s wife.

    Perhaps my power-hungry vein,

    Caused me to go a bit insane.

    For the stories have depicted,

    A fatal wound, self-inflicted.

    Did the puncture produce great pain?

    And did I vomit from the strain?

    Was the site red, blistered, and bruised?

    Did I weaken and act confused?

    Was I too numb to thrash about?

    Did I get dizzy and black out?

    Did my body begin to swell?

    Was my heart racing as I fell?

    Did I twitch as my body bled?

    How long before they deemed me dead?

    Were there easier ways to go?

    Was I, in fact, my greatest foe?

    Whispers persist of my demise,

    But is it all a pack of lies?

    Who am I, and how did I die?


    Answer:    Cleopatra     -       Snake Bite


    So, what is the point of this ode?  Well, spring is around the corner, bringing a fresh batch of snake bites and envenomations.   Tennessee plays host to 34 species of snakes, four of which are considered venomous: the Copperhead, the Timber Rattlesnake, the Pygmy Rattlesnake, and the Western Cottonmouth. 

    While every snake bite will produce minor redness, irritation, swelling, and bleeding to the bite site area, only the venom from these four Crotalinae family members can potentially trigger serious and possibly fatal effects in their Tennessee victims.  Distinguishing between a venomous bite and a non-venomous bite cannot be done based on the appearance of the bite site alone; thus all bites from snakes of unknown origins must be treated as venomous bites until envenomation is ruled out.  What symptoms must healthcare professionals observe for to determine if a Crotalinae bite occurred?


    With Crotalinae bites, the venom is commonly deposited intradermally , subcutaneously, or intramuscularly.  Venom insertion directly into blood vessels is rare.  Crotalinea snake venoms contain intricate mixtures of metal ions and complex proteins that elicit local, coagulation, and systemic abnormalities within minutes to several hours post-bite.  Abnormalities may include:

    Local Effects: Fang marks, scratches, or lacerations may be present.  Pain, swelling, ecchymosis, and hemorrhagic blebs can appear within minutes.  Edema can progress for several days with a risk of compartment syndrome development. Tissue necrosis with vascular damage may occur. Coagulation Effects:  Platelet and coagulation cascades can be affected, with increased INRs, prolonged PTTs, decreased fibrinogens, fibrin split products elevations, and thrombocytopenias.  Hemolysis and bleeding could ensue with widespread ecchymosis, petechiae, and purpura.


    Systemic Effects: Nausea, vomiting, diarrhea, numbness, and oral tingling may develop as early warning signs of systemic involvement, and abruptly progress to dizziness, agitation, confusion, tachycardia, hypotension, diaphoresis, weakness, paresthesias, fasciculations, rhabdomyolysis with hyperkalemia, hematuria,  hemoconcentration, airway compromise, intravascular volume depletion, angioedema, and shock.


    Assessment and management of the patient should begin immediately upon arrival.  The initial standard treatments of all snake bite victims should consist of:

    • Provide wound care and a tetanus vaccination update.
    • Remove any constrictive clothing, jewelry, or tourniquet if applied prior to arrival.
    • AVOID the use of ice or heat at the site as these will further damage the fragile tissue.
    • AVOID cutting the wound and applying tourniquets.
    • Elevate the bite area, allowing gravity to assist in limiting local edema.
    • Obtain IV access.
    • Mark and measure the circumference and edema edges every 30 minutes.
    • Maintain an NPO status until the envenomation is controlled
    • Laboratory workup on initial presentation, at six hours post-arrival, and at twelve hours post-arrival must include:
      • A complete blood count (H/H, platelets),
      • Coagulation profiles (PT, INR, PTT, fibrinogen),
      • A basic metabolic profile, and
      • A type & screen if a significant envenomation is present


    All snake bite patients who present with fang marks must be observed for a minimum of 12 hours with frequent reassessments for symptom progression.  Continued observation and aggressive management will depend on the envenomation’s severity.  Bites are classified as:

    No Envenomation:  Fang marks without other symptoms

    Minimal Envenomation:  Minor local effects without swelling progression beyond the bite site

    Moderate Envenomation: Swelling advancement beyond the bite site with modest coagulation and systemic abnormalities

    Severe Envenomation: Significant local effects with profound swelling, critical coagulopathies, and serious systemic symptoms

    The absence of all manifestations 12 hours after a bite denotes a lack of envenomation or a “dry bite”.  However, the slow onset and/or escalation of symptoms is not indicative of the envenomation’s severity; therefore, conferring with toxicology experts about the management of each snake bite case is always paramount, even if symptoms appear unremarkable on initial presentation and especially if the use of antivenom (CroFAB) is being considered.   The poison specialists and toxicologists of the Tennessee Poison Control Center can assist with snake bite questions and concerns.   Feel free to contact the TPC for consultations at any time.


    As a side note regarding the Cleopatra saga, legend conveys that she was bitten by an Asp or Egyptian Cobra, a symbol of royalty at the time.  Cobras belong to the Elapidae family and have strong neurotoxic effects. Cleopatra may have suffered from local pain, swelling, and necrosis, but paralysis of her cranial nerves could have begun within 15 minutes of the bite.  Coagulation abnormalities would likely not have been an issue for her.  Of interest, recent scholars have deduced that Cleopatra had keen knowledge of poisons and likely died after drinking a mixture of hemlock, wolfsbane, and opium, but that is a discussion for another question of the week.


    >Tennessee Herpetological Society. Snakes of Tennessee, 

    >Gray, M. Poison, not snake, killed Cleopatra, scholar says, CNN.

    > Poisondex Managements.  United States Snakes - Crotalinae, Truven Health Analytics Inc

    > Poisondex Managements.  African Snakes – Elapidae, Truven Health Analytics Inc




    This Question was prepared by: Cheri Wessels, RN, BSN, MBA, CSPI


    I am interested in any questions you would like answered in the Question of the Week.  Please email me with any suggestion at


    Donna Seger, MD

    Medical Director

    Tennessee Poison Center

    Poison Help Hotline: 1-800-222-1222


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