A 62-year-old male presented thirty minutes after being bitten by a snake in his garden. He stated that he thinks his finger was bitten twice. The patient presented with pain and swelling of his right hand and forearm.


  • Temp 99.1 degrees F
  • HR 105
  • BP 128/80
  • RR 20
  • SpO2 100% on room air

Skin: two small puncture marks noted to the palmar aspect of the right index finger, edema and erythema extending to just proximal of the wrist joint

MSK: pain upon palpation and with range-of-motion of the distal and proximal interphalangeal joints of the second digit

Laboratory data was without abnormality.

There was no thrombocytopenia or an elevated international normalized ratio (INR) on labs taken thirty minutes after the bite.

Poison control identified the snake as a juvenile cottonmouth, which has a yellow tail and brown coloring that turns darker with age.

Cottonmouth snakes are part of the subfamily Crotalinae, commonly known as pit vipers. Other Crotalinae snakes include water moccasins and rattlesnakes.

Crotalidae polyvalent immune fab (CroFab) should be given for:

  • Hypotension
  • Altered mental status
  • Progression of swelling beyond the bite site
  • Significant laboratory abnormalities  (thrombocytopenia, elevated INR, or fibrinogen less than one hundred)

The patient sustained a snake bite to his right index finger with significant edema and pain extending to his right wrist. Several areas of swelling were marked on the patient’s skin with timestamps and originally were contained to the dorsum of the hand. Labs were without abnormality, and the patient was not hypotensive.

The edema spread proximally to the right wrist and Crotalidae polyvalent immune fab (CroFab) was administered per hospital guidelines (six vials initially). The patient made a full recovery and was discharged home forty-eight hours after.

Take-Home Points

  • Cottonmouth snakes appear differently as juveniles; however, they are part of the subfamily Crotalinae and envenomation can still occur with significant symptoms.
  • CroFab should be administered for hypotension, altered mental status, the progression of swelling beyond bite site, or significant laboratory abnormalities including thrombocytopenia, elevated INR, or fibrinogen less than one hundred mg/dL [1].
  1. Ruha AM et al. Late hematologic toxicity following treatment of rattlesnake envenomation with crotalidae polyvalent immune Fab antivenom.
    Toxicon. 2011;57:53–59. PMID: 20920517

Keegan McNally, MD

Keegan McNally, MD

Emergency Medicine Resident
University of Central Florida College of Medicine
Keegan McNally, MD

Latest posts by Keegan McNally, MD (see all)

Larissa Dub, MD

Larissa Dub, MD

Associate Medical Director
Department of Emergency Medicine
Osceola Regional Medical Center
Larissa Dub, MD

Latest posts by Larissa Dub, MD (see all)