Rattlesnake Envenomation Follow-up

Updated: Jun 25, 2015
  • Author: Sean P Bush, MD, FACEP; Chief Editor: Joe Alcock, MD, MS  more...
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Further Outpatient Care

Discharge instructions should include the following:

  • Return immediately if swelling worsens or pain becomes severe.
  • Return immediately if any abnormal bleeding or bruising, petechiae, dark tarry stools, or severe headache occur.
  • Return for signs of wound infection, such as swelling, excessive tenderness, redness or streaks, heat, or drainage (pus). [26]
  • Return or follow up if a fever, itchy rash, joint pain, or swollen lymph nodes occur any time during the next few weeks.
  • Do not take nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, ibuprofen (Motrin, Advil), or naproxen (Naprosyn, Aleve) for 2 weeks after the snakebite. Acetaminophen (Tylenol) or a prescribed pain medication can be taken.
  • Do not participate in contact sports, undergo elective surgery, or have dental work for 2 weeks after the snakebite.
  • Drink plenty of liquids. Return if urine decreases in amount or becomes cola colored.
  • Referral to a physical therapist or surgeon may be indicated. If bitten on the foot or leg, crutches and crutch training should be provided. Elevate and mobilize affected extremity as tolerated.
  • Next day wound check should be performed at the physician's discretion on a case-by-case basis. The patient should return to the ED or follow up every 3 days for 2 weeks with repeat CBC, PT/INR, and fibrinogen. Laboratory results may need to be rechecked more or less frequently or for a longer or shorter duration on a case-by-case basis.

Further Inpatient Care

All patients with rattlesnake envenomation should be admitted to the hospital and remain there while undergoing treatment with antivenom. Close observation and frequent measurements of swelling (every 1-2 h) for approximately 24 hours after initial control is recommended.

Patients who are believed to have a dry bite in which no venom effects develop should be observed for at least 8 hours. A close follow-up and/or recheck examination is recommended.

Several reports in the literature have documented instances in which patients who were initially discharged with a mild envenomation returned in several hours with significant injury and required antivenom and admission. [27]


Inpatient & Outpatient Medications

Administer antihistamines if serum sickness develops. Steroids may be indicated for more severe cases of serum sickness.



All hospitals should have enough antivenom to treat at least one patient. However, antidote stocking varies and shortages do occur. Therefore, if antivenom is not available at the presenting hospital, the patient should be transferred to a facility where antivenom may be administered. However, if it is available, antivenom may be necessary to optimize stabilization of a patient prior to transfer.



Never handle a rattlesnake, even if it is believed to be dead. Serious, even fatal, envenomations have been documented to occur after handling the decapitated head of a rattlesnake up to 90 minutes after it was severed.

  • Do not reach or step into places outdoors that are not visible.
  • At home, remove debris in which snakes might hide (eg, log piles). Remove items, such as bird feeders, that might attract snakes—seeds that fall from bird feeders attract rodents, which attract snakes.
  • Heavy clothing (such as hiking boots) may retard some strikes.
  • Young children should be closely supervised, and older children should be educated to avoid snakes in indigenous areas.
  • Keep the garage door closed to prevent rattlesnakes from seeking shelter in the garage.
  • Many cases of envenomation involve alcohol. Do not use alcohol and place oneself in an environment that may be shared with rattlesnakes or play with snakes while intoxicated.


Complications of snake envenomation may include the following:

  • Bleeding, such as gastrointestinal or intracranial
  • Compartment syndrome
  • Necrosis with resulting tissue loss or loss of function
  • Rhabdomyolysis, myoglobinuric renal failure
  • Infection
  • Respiratory difficulty
  • Death (rare in the United States)
  • Antivenom-associated anaphylaxis  - Type I (immediate) hypersensitivity reaction, which may be life threatening; characterized by urticaria, airway swelling, wheezing, and shock
  • Antivenom-associated serum sickness - Type III (delayed) hypersensitivity reaction; characterized by fever, urticaria, lymphadenopathy, and arthritis and may occur 3 days to 3 weeks after antivenom


Before antivenom, estimates of mortality rates ranged from 5-25%.

Since the development of antivenom, rapid EMS transport, and emergency/intensive care, mortality rates have improved to less than 0.28% when antivenom is administered and to 2.6% when antivenom is not administered.

Less specific figures are available for morbidity data, although most patients recover fully after rattlesnake envenomation. The best estimates suggest that rattlesnake envenomation results in tissue loss, deformity, or loss of function in approximately 10% of patients.


Fewer than half a dozen deaths occur per year as a result of snakebite in the United States; most are caused by rattlesnake bites. Estimates of deaths each year from snakebite range from 30,000-110,000 worldwide. Up to 5 times as many individuals experience permanent morbidity. [28, 4]

US mortality with administration of antivenin is approximately 0.28%. Without antivenin being administered, mortality is approximately 2.6%.


Patient Education

Call professionals, such as animal control, to move snakes (if it is necessary to move the snake).

Never attempt to handle, possess, or kill venomous reptiles.

For patient education resources, see eMedicineHealth's patient education article Snakebite.