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A snake will sometimes bite in self-defence if disturbed or provoked.
Some snakes are venomous and can inject venom (toxin) as they bite. A bite from a venomous snake is a medical emergency as they can be deadly if not treated quickly.
Exotic snakes have been known to bite while being handled carelessly, or when they escape from their cages.
There is also a risk of being bitten while travelling abroad to tropical countries.
If an adder injects venom when it bites, it can cause serious symptoms including:
A foreign snake that injects venom when it bites can also cause:
Sometimes, venomous snakes can bite without injecting venom. This is called a ‘dry bite' and may cause:
Read more about the symptoms of snake bites.
Immediately after being bitten by a snake you should:
Seek immediate medical assistance by calling foran ambulance or visit your nearest accident and emergency centre.
You should give healthcare professionals a description of the snake to help identify it.
You may be admitted to hospital so the bite can be assessed and your condition closely monitored.
Read more about what to do if bitten by a snake and how snake bites are assessed.
In most cases of adder bites, the only treatment required is observation in hospital. As a precaution, you may be asked to stay in hospital for 24 hours to be monitored.
Anti-venom medication is an effective antidote to snake venom and can be used to treat more severe snake bites.
In most cases, children bitten by an adder will make a full recovery in about 1-3 weeks. Adults usually require more than three weeks to recover fully, and a quarter of adults will take between 1-9 months.
Read more about how snake bites are treated.
When a snake bites, it injects venom to immobilise its prey. As humans are too large for a snake to eat, most snakes bite in self defence.
Snake bites often occur when a person accidentally steps on a snake while out walking. However, sometimes people are bitten when they deliberately provoke a snake by striking it or trying to pick it up.
Read more about the causes of snake bites.
Follow the advice listed below if you are in an area where venomous snakes are found.
Adder and foreign snake bites can cause similar symptoms.
There are two types of snake bite:
The effects of venomous bites may be more severe in children because they are smaller.
Typical symptoms of a dry bite include:
If there are no other symptoms, such as swelling, it is probably a dry bite. However you should still visit your nearest emergency medical centre. This is because signs that venom has been injected might not appear until later, up to two hours or more after the bite.
Symptoms of snake bite where venom is injected include:
For foreign snake bites, symptoms may also include:
In the most severe cases, a venomous snake bite may cause:
Call for an ambulance if someone is bitten by a foreign snake or adder, and faints or develops symptoms of anaphylaxis (see below).
In a small number of people a snake bite can trigger a severe allergic reaction, known as anaphylaxis or anaphylactic shock. This can occur immediately after a bite or several hours later.
Anaphylaxis should always be treated as a medical emergency. Left untreated, anaphylaxis can be life-threatening.
Symptoms of anaphylaxis include:
Anaphylaxis can also cause a drop in blood pressure, which can lead to shock and cause symptoms such as:
Read more about anaphylaxis.
When a snake bites and injects venom, usually its aim is to immobilise its prey.
As humans are far too large for a venomous snake to eat, most snake bites occur when the snake is provoked into acting in self-defence.
In many cases, the snake is provoked by accident – for example, when a person accidentally steps on a snake while out walking. However, sometimes a snake bites after being deliberately angered by someone:
Snake bites that involve foreign (exotic) snakes kept as pets usually occur when someone handles or 'plays' with them.
Snake venom contains toxins (poisons) designed to kill or immobilise the snake’s prey. There are four main types of snake venom toxins:
The four types of toxins are discussed in more detail below.
Haemotoxins destroy red, oxygen-carrying blood cells, and disrupt the blood's ability to clot.
They can also cause a drop in blood pressure, which can result in tissue and organ damage, loss of consciousness and death.
Neurotoxins block or damage nerves where they connect to muscles, preventing the nerve signals getting through.
Myotoxins can cause permanent damage by destroying muscle cells and causing pain and muscle weakness.
They may also damage your kidneys, which filter waste products from your blood, causing your urine to be very dark.
There are a number of misconceptions about what to do immediately after being bitten by a snake. For example, you should never try to suck or cut the venom out.
Follow the advice below if you or a companion is bitten by a snake.
If you or someone you are with is bitten by a snake you should not:
If you are bitten by a snake you should visit your nearest emergency medical centre, or call an ambulance if you need urgent travel assistance.
If a snake bites you while you are abroad, you should assume it is a medical emergency and contact the relevant emergency medical services.
In most cases, following a bite, you will need to stay in hospital for a short period. This is so that staff can keep you under observation in case you develop symptoms that suggest venom has been injected.
As a precaution, you may be asked to stay in hospital for at least 24 hours so your blood pressure and general health can be monitored.
Anti-venom medications are antidotes to snake venom and can be used to treat more severe snake bites.
Anti-venoms are produced by injecting a small, non-life-threatening amount of snake venom into a large animal, usually a horse.
The animal's immune system (natural defence system) produces antibodies. Antibodies are proteins that stick onto toxins and are capable of neutralising their effects. The antibodies are then taken from the animal, purified and stored until needed.
In some people, anti-venoms can trigger a severe allergic reaction called anaphylaxis, so it is important you are closely monitored after receiving your first dose.
Due to the risk of anaphylaxis, anti-venom should only be given by a qualified healthcare professional.
In cases where a snake bite is severe, and your blood pressure has fallen significantly, you may need intravenous fluids (into a vein in your arm). You may also need a blood transfusion if you have lost a lot of blood.
Recovery times for snake bites can vary depending on the species of snake involved.
In most cases, children bitten by an adder will make a full recovery in 1-3 weeks. Adults usually take more than three weeks to recover fully, with a quarter taking between 1-9 months.
During the recovery period, you may experience episodes of pain and swelling in the area of your body that has been bitten. These symptoms can usually be controlled by taking over-the-counter painkillers, such as paracetamol.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.