Cottonmouth snakes, also known as water moccasins, are venomous pit vipers found throughout the southeastern United States, often near water bodies. While their bites can be serious and cause significant local tissue damage, fatalities are rare with prompt and appropriate medical treatment. Approximately 7,000 to 8,000 people are bitten by venomous snakes in the U.S. each year, but only about five to six deaths occur annually, with cottonmouths accounting for less than 1% of these fatalities. Understanding their venom, bite response, and identification helps minimize risk.
The Venom and Its Effects
Cottonmouth venom is primarily hemotoxic, breaking down blood cells and hindering clotting, which can lead to internal bleeding. The enzymes within the venom also cause local tissue destruction and inflammation at the bite site.
Upon envenomation, individuals experience immediate, severe, burning pain and rapid swelling around the bite area. Skin discoloration and bruising are common as the venom affects blood vessels and soft tissues. Beyond localized effects, bites can result in tissue and muscle damage, and in severe cases, complications like compartment syndrome. Systemic symptoms like nausea, vomiting, and abnormal blood clotting are uncommon.
Immediate Steps After a Bite
If bitten by a cottonmouth, seeking immediate medical attention is essential. Call 911 or your local emergency number without delay, as antivenom administration is the definitive treatment to stop further damage. Remaining calm and still helps prevent the venom from spreading quickly through the body.
While waiting for emergency services, remove any jewelry, watches, or tight clothing from the bitten limb to accommodate swelling. Keep the affected limb immobilized and, if possible, position it below heart level. Gently wash the bite area with soap and water and cover it with a clean, dry dressing. Do not attempt to cut the wound, suck out the venom, apply a tourniquet, or use ice, as these methods are ineffective and can cause further harm.
Recognizing and Avoiding Cottonmouths
Cottonmouths are semi-aquatic pit vipers with thick, muscular bodies. They have a distinctive broad, triangular head that is wider than their neck, vertical pupils similar to a cat’s, and heat-sensing pits between their eyes and nostrils. When threatened, they display the bright white, cotton-like interior of their mouth as a warning.
These snakes are confused with non-venomous water snakes, but cottonmouths swim with most of their body visible on the surface of the water, with their head held high. Water snakes, conversely, swim with only their heads above water. To avoid encounters, be mindful in their habitats such as swamps, marshes, and slow-moving water bodies. Wearing appropriate footwear, removing debris or tall grass from yards, and not attempting to handle or provoke any snake prevent bites.