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How do you tell if a snake is poisonous or not?

How do you tell if a snake is poisonous or not?

Most snakes are harmless, but some species are highly venomous and can potentially deliver a fatal bite. Knowing how to identify venomous snakes and take appropriate precautions can help prevent unfortunate encounters. This article provides tips on recognizing dangerous snakes, understanding venom potency, and responding appropriately if bitten.

Identifying Venomous Snakes

There are several ways to determine if a snake you encounter may be venomous:

Triangular Heads

Many venomous snakes have triangular-shaped heads. This shape allows room for the venom glands and large fangs. Nonvenomous snakes typically have narrower, rounded heads. A triangular head alone doesn’t guarantee danger, but it’s an important clue to pay attention to.

Elliptical Pupils

Venomous snakes often have vertical, cat-like pupils instead of round ones. If you can clearly see a snake’s eyes, pupil shape can help distinguish hazardous from benign snakes. Again, pupil shape alone doesn’t definitively indicate venom, but it’s one more useful indicator.

Heat-Sensing Pits

Pit vipers, a venomous snake group including rattlesnakes, copperheads, and cottonmouths, have distinctive heat-sensing pits between their eyes and nostrils. These pits allow them to accurately strike warm-blooded prey. If you see a small indentation between a snake’s eyes and nose, it’s likely a pit viper.

Prominent Fangs

Venomous snakes tend to have long, hollow fangs used to inject venom deep into prey. These fangs fold back when the mouth is closed but are clearly visible when open. If you can safely observe a snake’s open mouth and see long fangs, treat the snake as dangerous.


The distinctive buzzing rattle on a snake’s tail warns of danger. Rattlesnakes are a distinctly venomous group found throughout North and South America. Any snake making a rattling sound should be avoided and treated as venomous.

Distinctive Markings

Some venomous snakes have unique stripes, spots, or other patterns signaling their danger. Familiarize yourself with local venomous species’ markings so you can recognize them at a safe distance. For example, coral snakes have bright color banding, cottonmouths have dark crossbands, and many vipers have diamond, chevron, or blotchy patterns down their backs.

Venom Potency

Not all venomous snake bites are equally dangerous. Some have mild venom that may cause pain and swelling but very rarely death. Others, like black mambas and inland taipans, deliver an extremely toxic venom that can quickly cause collapse or death without rapid treatment. Here are some indicators of highly potent venom:

Snake Group Venom Potency
Rattlesnakes Moderate to high
Coral snakes Highly potent neurotoxin
African spitting cobras Extremely toxic venom
Black mambas Rapid acting, highly toxic
Inland taipan Most toxic land snake venom

The snakes listed above all deliver a potentially life-threatening envenomation requiring rapid medical treatment. But even snakes with milder venom can make you extremely sick or disable a body part like an arm. It’s wise to treat all venomous snake bites seriously.

First Aid for Snake Bites

If you are bitten by a venomous snake, follow these first aid steps while awaiting medical care:

1. Call Emergency Services

Dial 911 or your local emergency number immediately. Antivenom treatment may be necessary so don’t delay seeking medical care. Providers can offer life-saving treatment and manage complications.

2. Remain Calm and Still

Sit or lie down in a comfortable position and avoid unnecessary movement. This prevents venom from spreading through your body. Staying calm also keeps your heart rate lower, slowing venom absorption.

3. Remove Jewelry and Constricting Items

Remove anything constricting the bitten limb like watches, rings, boots, etc. This prevents venom blocking circulation as swelling develops.

4. Position the Limb Below Heart Level

If possible, gently position the bitten arm or leg below the level of your heart. This uses gravity to slow venom circulation through your body.

5. Clean the Wound

Gently clean the bite wound with soap and water if available. This removes some venom left on the skin’s surface.

6. Cover the Wound Lightly

Apply a clean, dry bandage wrapped snugly over the bite. This helps prevent infection but avoid wrapping it too tightly.

7. Monitor Breathing Closely

Watch closely for signs of slowed or troubled breathing. Venom can paralyze muscles including those used for respiration.

8. Avoid These First Aid Measures

Do NOT –

  • Cut into or try to suck out venom
  • Apply a tourniquet
  • Apply cold packs
  • Drink alcohol as a painkiller

All of these can worsen injury or speed venom absorption. Follow the steps above and focus on remaining still and calm until emergency responders arrive.

Prevention Tips

Use these proactive measures to lower your risk when in areas where venomous snakes live:

  • Wear sturdy boots and long pants when hiking
  • Avoid reaching blindly into rock crevices or dense brush
  • Don’t step over fallen logs or other obstacles you can’t see past
  • Carefully check grounds around a home or campsite perimeter
  • Keep grass and brush trimmed short around high-traffic zones
  • Close up any gaps snakes could enter around windows or foundations

Staying observant and proactive are your best defenses against venomous snake bites.


While snake encounters can be startling, most are not dangerous. Learn to identify local venomous species, give all snakes space, and take preventive precautions in snake-prone areas. If bitten, remain calm, follow first aid steps, and get medical care immediately. Proper identification and emergency response can help ensure a potential bite ends safely. Be snake smart, not afraid.