Resident Expert in Snakebite and Envenomations at Remote Medical International
I love it when this question comes up, since snakebite medicine is what I do for a living! Pretty much everything that is common knowledge about snakebite first aid is either completely ineffective or potentially dangerous. The only definitive treatment for a serious snake envenomation is the appropriate antivenom, but here is some specific advice on what to do in the field so you can make it to the hospital alive and receive antivenom. I wrote a very long post to answer this question but I am afraid that it may dissuade the casual reader, so I am including the sparknotes version below. You can read the here if you want the detailed version: Jordan Benjamin's answer to What should you do if a snake bites you in the backcountry many hours away from medical care?
The Short Version
DO NOT make a tourniquet, DO NOT cut and suck, DO NOT apply the sawyer extractor or other commercial “snakebite kits”, DO NOT electrocute yourself with a stun gun, and do not follow any strange recommendations you receive from other hikers on the trail. No first aid is often less harmful than bad first aid when it comes to snakebites!
1) Carefully walk backwards and find a safe space to sit down nearby before the venom drops your blood pressure and you pass out and hit your head.
2) Remove any rings, watches, bracelets, and anything else that could become a tourniquet if your limb swells up like a balloon.
3) Circle the site of the bite with sharpie and write the time next to it. Mark the edge of the swelling, make a list of your symptoms, and repeat every 30 minutes or so. Always record the time. The photos below demonstrate this:
Circle the site of the bite and mark the time that it occurred…
…Then mark the leading edge of the swelling and repeat the process as the swelling advances up the limb. It is particularly important to record the time that swelling reaches and/or passes the various joints on the affected limb.
4a) If you are positive that you have been bitten by a neurotoxic snake, apply a pressure immobilization bandage as shown in the diagram below, but DO NOT USE THIS FOR VIPER BITES! Once it is on you can't take it off and it will slow your ability to walk out so choose wisely. For a viper bite, this may result in much more extensive tissue damage to the limb and should not be used.
4b) If you begin to experience signs of anaphylaxis (swelling of face, mouth, or throat; hives; difficulty breathing, etc) use an epi-pen if you have one and then take Benadryl and Zantac. If you don't carry these things in the backcountry you should do yourself a favor and get them because you can't macgyver an epi-pen out of nothing. A lot of things can cause anaphylaxis and epi-pens can also be used as a last-ditch intervention for severe asthma attacks.
For more information about how to treat anaphylaxis in the backcountry see my blog post on the subject here: How to treat severe allergic reactions and anaphylaxis in the backcountry (and a trick to squeeze a few extra doses out of your epi-pen) by Jordan Benjamin on Snakebite and Wilderness Medicine
5) If you have cell phone reception call 911*, tell them where you are, when you were bitten, and the list of current symptoms you just wrote down.
*If you aren’t in the United States, look up the local emergency services number (whatever the equivalent of 911 is) and add it to your phone before you head out.
6) If you don't have reception, plot the safest and most expedient path to find it or reach a vehicle (whatever is safer/faster) and then start hiking out.
Time is tissue and it may be better to walk yourself out in an hour than to sit on your butt for 5 hours until a helicopter can show up. I think the idea that one should do everything possible to avoid speeding up circulation of venom is bad advice. You are already terrified from being bitten by a snake so your heart rate and blood pressure are already sky high. I've treated lots of bites in remote places and pretty much all of them had to hike out to reach the hospital. Figure out the fastest, safest route to find help and then make it happen.
Once again, for the long version of how to survive a snakebite in the backcountry go to this post: Jordan Benjamin's answer to What should you do if a snake bites you in the backcountry many hours away from medical care?
This is a Sawyer Extractor, and you should never use it for a snakebite! If you want to learn more about why you shouldn’t use it, read the longer post linked to earlier or check out the more specific answer below: Jordan Benjamin's answer to What is the Quora consensus on snake bite kits? I've heard arguments on both sides.