Black Widow Spider Bites

black widow bite treatment

Black widow spiders are commonly found throughout the entire world.  They are found all over the United States but most commonly in the Southern and Western states.  The southern black widow is very easily recognized by its trademark black, shiny body and bright red hourglass symbol on their belly. The northern black widow has red dots along the back side of their abdomen as well as two crosswise bars on the underside.  The markings can also be yellow or white in color rather than the typical red. 

Black widow spider venom is 15 more potent than that of the rattlesnake.  They are not as deadly, however, because of the small amount of venom that is injected into humans.  Black widows live in dark corners of protected areas.  They are most active at night. The females are only aggressive when feeling threatened or disturbed.

The black widow gets its eerie name from its interesting mating behavior.  After mating, the female spiders will not only kill but also eat their mate.  This leaves them as widows, thus comes the name the black widow.

Is Their Bite Deadly?

The venom from a black widow contains the protein latrotoxin which is a neurotoxin that targets the central nervous system.  It changes the structure and function of nerve terminals. It triggers rapid exocytosis (which is where the nerve cells eject calcium, waste, and chemical transmitters) which leaves the nervous cells unable to communicate with each other.

Individuals bit by a black widow may not immediately know they have been bit.  They may feel a slight pinprick sensation or they may feel nothing at all.  Symptoms may be mild or may be life threatening depending on the individual.  The elderly, children, and immunocompromised individuals are more susceptible to extreme reactions. Symptoms varies from person to person, but individuals will start experiencing symptoms within in a few hours of the bite.  These symptoms can include the following:

Early stages of black widow bite.

Early stages of black widow bite.

  • Redness and swelling around the bite
  • Pain that is not limited to the site of the bite
  • Severe chest and abdominal pain
  • Muscle cramping and spasms usually within eight hours
  • Weakness or tremors
  • Rash and itching
  • Swollen eyelids
  • Fever
  • Headache
  • Nausea, vomiting, and chills
  • Difficulty breathing (due to diaphragm paralysis)
  • Hypertension (high blood pressure) 
  • Sweating

What Should Someone Do If They've Been Bit?

Most importantly, if an individual thinks they have been bit by a black widow, be sure to encourage them to see a healthcare provider immediately.  Everyone is different and there's no way of predicting how severe the reaction may become.  Here are a few other quick interventions that can be performed within a couple minutes upon leaving to go to the hospital:

  • Clean the bite area with soap and water.
  • Place a cold washcloth or ice pack on the affected area.  
  • Elevate the area to prevent swelling.
  • Put an antibiotic cream on the bite.

Medical Treatment

Healthcare providers will assess the patient's symptoms for severity to determine if they need treatment.  If necessary, they may be prescribed muscle relaxants, benzodiazepines, and/or strong pain medications.

Individuals may need to be hospitalized if symptoms are severe enough in nature.  In these situations, individuals may require medications to help with symptom management and venom neutralization.

Most widow spider envenomations may be managed with opioid analgesics and sedative-hypnotics. Antivenom may be indicated for patients who have severe envenomations with pain refractory to these measures. Antivenom should be considered when envenomation seriously threatens pregnancy or precipitates potentially limb- or life-threatening effects (eg, severe hypertension, unstable angina, priapism, compartment syndrome [7] ). On average, antivenom administration results in resolution of most symptoms a half an hour after administration, and it has been shown to decrease the need for hospitalization.
— Medscape


The anti-venom is made from a substance found in horse blood and helps to neutralize the venom from the black widow.  There are potential side effects of the anti-venom so individuals who receive it will be monitored for 8-12 days afterward.  Calcium gluconate administration used to be a line of treatment for bites, but it has been found to be ineffective and is no longer recommended.



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AuthorCourtney Tracy