Poisonous snakes bite about 7,000 people in the United States every year, resulting in about 20 deaths. But with prompt, correct care, they need not be fatal.
If you can, try to identify the snake. This will help the hospital determine the best course of action. However, don't waste time! If you can't find or identify the snake, then just try to get the person to the hospital as soon as possible. The sooner someone is treated, the better their prognosis will be. You need to call 911 as soon as you can. If possible, have someone stay with the person to continue treating them and have someone else call for help.
Place the person in the supine position (which is where the person is laying on their back with their face up). This will help slow venom metabolism and absorption.
Authorities disagree about whether or not a constrictive tourniquet should be applied. However, if you choose to apply one, you need to immobilize the affected arm or leg below heart level.
If you applied a tourniquet you need to check the distal pulse of the affect limb. Check the pulse regularly and loosen the tourniquet as needed. Remember that the goal of the tourniquet in this case is to slow lymphatic drainage, not blood flow. The tourniquet should be applied about 4 inches above the bite. It should be loose enough so that you can slip your finger between the band and the skin.
Once the tourniquet is applied do not remove it. Only a doctor should decided when to remove it. If possible, you should make a mental note or write down the exact time the tourniquet was applied.
At this point there isn't much more you can do, so you need to focus on getting the person help as soon as possible. As soon as you are able to, you need to call 911.