Symptoms of snake bites 

Adder and foreign snake bites can cause similar symptoms.

There are two types of snake bite:

  • dry bites where the snake injects no venom (liquid containing toxins produced by the snake)
  • venomous bites  where the snake injects venom

The effects of venomous bites may be more severe in children because they are smaller. 

Dry bites

Typical symptoms of a dry bite include:

  • mild pain at the site of the bite caused by mechanical punctures by the snake’s fangs
  • anxiety

If there are no other symptoms, such as swelling, it's probably a dry bite. However you should still visit your nearest accident and emergency (A&E) department. This is because signs that venom has been injected might not appear until later, up to two hours or more after an adder bite, or even longer after an exotic snake bite.

Venomous snake bites (adder and foreign)

Symptoms of an adder bite when venom has been injected include:

  • severe pain at the location of the bite
  • swelling, redness and bruising at the location of the bite, spreading up the bitten limb
  • nausea (feeling sick) followed by vomiting
  • diarrhoea
  • itchy lumps on the skin (hives or nettle rash)
  • swelling of the lips, tongue and gums
  • breathing difficulties with wheezing, similar to asthma
  • mental confusion, dizziness or fainting 
  • irregular heartbeat

Foreign snake bites

For foreign snake bites, symptoms may also include:

  • dizziness, mental confusion, faintness, collapse and shock
  • bleeding from the mouth, nose and wounds
  • vomiting blood or passing blood in urine or stools
  • muscle paralysis, which can lead to breathing difficulties

In the most severe cases, a venomous snake bite may cause:

  • extensive swelling, blistering and eventually gangrene (death of tissue) in the area of the bite
  • paralysis, starting with drooping of the upper eyelids and progressing down the body to produce an inability to swallow, breathe or move
  • shock and loss of consciousness
  • kidney failure with little or no urine being passed
  • massive blood loss, due to bleeding from the mouth, nose and wounds, vomiting blood and passing blood in urine or stools
  • death

Dial 999 to request an ambulance if someone is bitten by a foreign snake or adder, and faints or develops symptoms of anaphylaxis (see below).

Anaphylaxis

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:

  • itchy skin with hives and redness
  • swollen face, lips, tongue and throat
  • swelling in the throat that can cause breathing difficulties
  • wheezing and difficulty breathing 
  • rapid heartbeat
  • nausea, vomiting and diarrhoea

Anaphylaxis can also cause a drop in blood pressure, which can lead to shock, and cause symptoms such as:

  • dizziness or mental confusion
  • faintness, loss of consciousness or collapsing 
  • cold and clammy skin
  • blindness

Read more about anaphylaxis.


Adder bites

Adder bites can be painful but are not usually serious.

About seven out of 10 adder bites cause only pain and swelling in the area that has been bitten.

Since records began in 1876, there have only been 14 reported deaths as a result of adder bites, with the last death occurring in 1975.

What to do after a snake bite

You should go to your nearest accident and emergency (A&E) department, if you are bitten by a snake, even if your symptoms are mild.

Hospital staff will check for signs of whether venom has been injected through the bite.

Page last reviewed: 11/08/2014

Next review due: 11/08/2016