Are bites from juvenile snakes more dangerous than bites from adults?
No. It’s a common misconception that juvenile snakes cannot control how much venom they deliver in a bite and are therefore more dangerous. First, juveniles DO have the ability to regulate how much venom they release. Secondly, even if juveniles did not have that control, their total venom volume is much less than that of an adult snake.
It is true that in some species the ratio of venom components changes as a snake ages, and some toxins may be more potent in juveniles than adults. However, the total volume of venom delivered is a much more important factor in determining the severity of a bite. That is why , on average, a bite from an adult snake is worse than a bite from a juvenile snake.
The most important thing to remember is that every bite is unique, and a bite from any pit viper of any age has the potential to be mild, moderate, or severe.
Please see this excellent article by Dr. Hayes describing the ability of juvenile prairie rattlesnakes to regulate their venom: https://pdfs.semanticscholar.org/ab0a/a8df73b5b0cd01ffdbde538aa3d16a5ee049.pdf
What’s the best way to position the affected extremity after a snakebite?
When determining how to position the affected extremity following a snakebite, there are two things to consider: the type of snake and whether you’re already at the hospital or still in the pre-hospital environment.
Experts agree that crotalid (copperhead, cottonmouth, rattlesnake) envenomations should be ELEVATED in the hospital. Elevate the extremity at least 45° (ideally at least 60°) without allowing the knee or elbow to bend. It’s one of the first recommendations in the unified treatment algorithm for the management of crotaline snakebite in the U.S.: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3042971/
At the 2020 North American Congress of Clinical Toxicology, Dr. Beuhler presented data confirming that patients did better with elevation.
Pre-hospital positioning is a little controversial. Some people recommend keeping the affected extremity at heart level because they fear that elevation will increase the systemic absorption of the venom. I recommend early and aggressive elevation, because the volume of venom is so insignificant that elevation is unlikely to make a difference in absorption. On the other hand, the volume of fluids that accumulate in the affected extremity is significant, and elevation will reduce that swelling. He reports seeing dramatic improvement within 30 minutes of elevation.
The affected extremity should never be placed below heart level. This will increase the swelling and hydrostatic pressures that lead to tissue injury.
Coral snake envenomations do not cause significant swelling, and I tell patients to keep the affected extremity in whatever position is most comfortable.
You can read my article here: https://medium.com/natural-world/how-to-position-a-snakebite-9430fc988af
Are venom extraction devices useful following a snakebite?
No! Extraction devices are not helpful in snake envenomation. They remove almost no venom following a bite (no more than 2% in one study). Certainly not a clinically significant amount.
Furthermore, there is good evidence that they are harmful. They can cause a negative pressure injury and, by preferentially removing interstitial fluid, these extraction devices could theoretically concentrate the venom.
These kits are good for one thing: profits for the people who manufacture and sell them. But they are certainly not beneficial to a snakebite victim.
Here are some excellent studies that look at the risks and benefits of extraction devices:
This one is the best-titled editorial ever: https://www.researchgate.net/publication/8898869_Snakebite_suction_devices_don’t_remove_venom_they_just_suck
After a snakebite, should you use a tourniquet or a lymphatic constriction bandage or anything similar?
When it comes to our native crotalids (copperhead, cottonmouth, rattlesnake), AVOID any technique that attempts to confine the venom in the affected extremity, including a tourniquet, a lymphatic constriction band, and pressure immobilization.
A tourniquet is great when you want to stop life-threatening bleeding, but you don’t want to cut off the arterial blood supply to a bitten extremity.
Although lymphatic constriction bands and pressure immobilization don’t cut off the blood supply, they do (theoretically) confine the venom to the affected extremity, which, particularly when combined with the increased swelling, causes increased local tissue injury. Because local injury is seen in > 95% of crotalid envenomations, and for most envenomations that’s the only significant manifestation, we need to avoid this. All of the major toxicology organizations produced a position statement condemning the use of pressure immobilization for native crotalid envenomations.
Furthermore, if pressure immobilization is performed incorrectly, it can actually enhance systemic venom absorption while simultaneously causing local injury. And, as you can see in Dr. Norris’ paper, most people perform PI incorrectly: https://pubmed.ncbi.nlm.nih.gov/15813142/
You can read the pressure immobilization position statement here: https://www.acmt.net/_Library/Position_Drafts/Pressure_Immobilization_After_North_American_Crotalinae_Snake_Envenomation_-_JMT.pdf
Is there any benefit in applying an electric current to a snakebite?
I hate that I even have to address this one, but enough people try or recommend this nonsense that I could not let it go unanswered. Electricity is not the cure for an envenomation. It causes local damage and occasionally kills the victim.
Is diphenhydramine (Benadryl) helpful following a snakebite?
I get asked about this all of the time. There’s absolutely NO BENEFIT from Benadryl following your typical snake envenomation. Benadryl is an antihistamine. Histamine is not a major component of snake venom, so antagonizing the effects of histamine accomplishes nothing. It does not “buy time” or “reduce inflammation” or anything of the sort. All it does is give people a false sense of security and distracts them from the most important thing: getting to the hospital so that someone can determine the need for antivenom, which is the definitive treatment for snake envenomation.
The only time Benadryl may be helpful is in the rare case of an allergic reaction to either the venom or the antivenom. And in serious reactions, the drug of choice would be epinephrine, not Benadryl, which helps for hives and itching but not the cardiac or respiratory complications.
Please read this excellent article by Dr. Nick Brandehoff: https://www.snakebitefoundation.org/blog/2019/7/3/benadryl-is-useless-for-treating-snakebites-dr-nick-brandehoff
You can also read the most recent anaphylaxis practice guidelines, which address the lack of utility of antihistamine, here: https://www.aaaai.org/Aaaai/media/MediaLibrary/PDF%20Documents/Practice%20and%20Parameters/Anaphylaxis-2020-grade-document.pdf
Why does it seem like some physicians won’t give antivenom when it’s indicated?
There are multiple reasons why a doctor may choose to not treat a patient with antivenom even when it is clearly indicated:
- He or she may think snakebites are not that serious.
- He or she may not believe antivenom is effective.
- He or she may not think antivenom is safe.
- He or she may think treatment with antivenom is not worth the cost.
- He or she may not want to bother with treatment because s/he is uncaring and/or lazy.
- He or she may face pressure from hospital leadership not to treat patients for various reasons, including financial.
We know that bites have the potential to cause serious local and/or systemic toxicity. We also know that antivenom can prevent and treat local, hematologic, and systemic toxicity. We know that CroFab has an excellent safety profile, with an incidence of acute adverse reactions ranging from 1.4 – 8%.
Antivenom is not cheap, but neither is a prolonged or permanent disability. Antivenom accelerates recovery in a clinically significant way. Furthermore, not all bites that go untreated will recover fully, and the incidence of permanent disability or disfigurement increases with the severity of the bite.
Administer antivenom for any of the following:
- significant or progressive local tissue damage e.g. tenderness, swelling, hemorrhagic bleb
- hematologic toxicity, e.g. PT > 15 s, fibrinogen < 150 mg/dL, platelets < 150K/µL
- systemic toxicity, e.g. hypotension, airway swelling, neurological toxicity
Most physicians recognize the need to treat when there is systemic or hematologic toxicity. A common pitfall is to fail to treat the local findings. If the swelling and tenderness are more than minimal and have extended beyond a major joint (e.g. wrist, ankle), antivenom is warranted. If there is significant local tissue injury, e.g. necrosis, antivenom is also indicated, even if the swelling has not progressed across a joint. Antivenom is most effective when given early, and the previous approach of waiting for the damage to cross two joints should be abandoned.
Read the unified treatment algorithm here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3042971/
What about copperhead bites?
Copperhead envenomations should be treated like other native crotalid envenomations. Although the average copperhead envenomation tends to be less severe than a typical rattlesnake envenomation, any native crotalid envenomation can result in significant local and systemic toxicity. Furthermore, many snakes go unseen, and among those that are observed, misidentification is common. So it might not even be a copperhead….
A randomized clinical trial demonstrated that even mild copperhead envenomations recover more quickly when treated with CroFab compared to placebo. CroFab also reduced total opioid requirements. As the severity of the envenomation increases, the benefits of antivenom are increasingly apparent.
Randomized clinical trial of CroFab for copperhead envenomations: https://pubmed.ncbi.nlm.nih.gov/28601268/
Early antivenom administration accelerates recovery: https://pubmed.ncbi.nlm.nih.gov/30175628/
Antivenom reduces opioid requirements: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6526891/
Should antibiotics routinely be prescribed following snakebite?
Antibiotics should not be prescribed routinely following snakebite. Infection of any type is exceptionally uncommon following envenomation.
In a study from the University of Arizona, infection was observed in fewer than 1% of cases: https://pubmed.ncbi.nlm.nih.gov/30392637/
In a study using data from the North American Snakebite Registry, the incidence was less than 5% of cases: https://www.researchgate.net/publication/277656029_Antibiotic_Use_in_the_Management_of_Snake_Envenomation_A_Retrospective_Cohort_of_Patients_Reported_to_the_ToxIC_North_American_Snakebite_Registry
Prophylactic antibiotics should not be administered because the side effects outweigh the benefits.
Indiscriminate antibiotic use also contributes to antibiotic resistance. And it’s an unnecessary expense: https://pubmed.ncbi.nlm.nih.gov/9143566/
Finally, there’s in vitro evidence that some antibiotics potentiate certain snake venom components: https://www.mdpi.com/2072-6651/12/4/240/htm
Antibiotics should only be prescribed when there is clinical evidence of an infection.
Who is most likely to be envenomated by a snake?
Most snakebites in the U.S. occur when someone UNINTENTIONALLY interacts with a snake. A study by Ruha et al. found that only 19% of bites occurred after someone intentionally engaged with the snake. It is certainly true that “messing” with a snake will increase your risk of being bitten, but most bites still occur when someone is unaware of a snake in his or her vicinity. That’s why it’s so important to wear appropriate footwear and never stick your hand into a hole or bush blindly.
What's a dry bite?
Not all snakebites result in envenomation. In about 10% to 15% of pit viper bites and 30% to 50% of coral snake bites that present to the emergency department, no venom was delivered. We call this a dry bite. Because no venom is delivered, there will be minimal signs and symptoms. It’s essentially the same as getting pricked by a thumbtack.
IF A PATIENT IS HAVING BRUISING, SWELLING, PAIN, ETC., IT INDICATES THERE HAS BEEN AN ENVENOMATION AND IS THEREFORE NOT A DRY BITE.
The absence of lab abnormalities does not mean it’s a dry bite.
Snakebites are a dynamic process. The diagnosis of dry bite cannot be made after 30 minutes of observation. Not even two hours. Not even four hours. Patients who may have been bitten by a venomous snake should be observed for AT LEAST eight hours. If there are no local findings, no systemic toxicity, and no hematologic lab abnormalities, then it is reasonable to make the diagnosis of a dry bite. To call it a dry bite after one hour of observation is a recipe for disaster and has resulted in some pretty expensive lawsuits.
This observation is emphasized in the unified treatment algorithm, which you can read here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3042971/
If you’re bitten by a snake, should you bring the snake to the hospital so you get treated correctly?
You should NOT bring the snake – dead or alive – to the hospital if you have been bitten. Let’s think about all the possible scenarios:
- Bringing a live snake is obviously potentially dangerous to humans as well as the snake.
- Bringing a dead snake is also dangerous to humans. People forget that dead snakes can envenomate, typically for about 30–45 minutes after the fatal injury, but the record is approximately 8.5 hours.
Don’t believe me? Check these out:
This guy DIED after getting bitten by a dead prairie rattlesnake: https://pubmed.ncbi.nlm.nih.gov/29457505/
This guy almost died after getting bitten by a dead rattlesnake: https://www.google.com/amp/s/abcnews.go.com/amp/US/texas-man-recovering-bitten-rattlesnake-decapitated/story%3fid=55697915
This guy got envenomated by a dead copperhead: https://www.wemjournal.org/article/S1080-6032(16)30225-3/pdf
Most importantly, and this may blow some people’s minds, we don’t actually need to know what snake is responsible for the bite! All we have to do is determine whether or not it is a pit viper envenomation, and that’s a clinical diagnosis. A physician who is knowledgeable about snakebites can easily distinguish a bite from a crotalid from a bite from a non-venomous snake. And, in regions where this is relevant, it’s also easy to distinguish a coral snake bite from a pit viper bite and from a bite from a non-venomous snake.
Once we determine whether or not it’s a pit viper bite, we’re good. Because CroFab is FDA-approved for all North American pit vipers: copperheads, cottonmouths, rattlesnakes. We do not need to know the species in order to treat appropriately.
If you can take a picture of the snake quickly and safely, that’s great. Almost everybody has a camera phone, and it’s nice to know the species for epidemiological purposes. However, we definitely don’t want to delay transport or treatment trying to ID the snake. You treat the patient based on the signs and symptoms.