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Poisonous Bites and Stings

Penetrating injuries from snakes, scorpions, insects, or marine life that are followed by an injection of venom

  • Walking or swimming in areas where venomous biting or stinging animals live is a risk factor
  • Age, gender, and genetics are not significant factors

The risk of receiving a poisonous bite or sting varies considerably in different parts of the world. The animals most commonly responsible for venomous bites and stings include snakes, spiders, scorpions, and marine animals such as jellyfish. If you are travelling abroad, it is important to seek advice about the risk of encountering venomous animals, especially if you intend to go camping, hiking, or swimming. You should also take appropriate precautions to prevent being bitten or stung (see Avoiding bites and stings).

What are the causes?

Worldwide, there are many species of venomous snake, but only one of these, the adder, occurs naturally in the UK. Poisonous spiders are found in parts of America and Australia. For example, black widow and brown recluse spiders occur in North America, while Australia is home to the redback and funnel back spider. Venomous scorpions are found in several parts of the world, including North Africa, South America, and India.

Poisonous marine animals, including jellyfish and sea anemones, can be found around the shores of Britain. Poisonous fish, such as stingrays and scorpion fish, are found only in tropical waters.

What are the symptoms?

If you are bitten by a snake and there are no fang marks, no venom has been injected and there will be no symptoms. If there is venom in the wound, symptoms may appear immediately or over the next few hours. Initial symptoms occur around the bite and may include:

  • Swelling and discoloration.

  • Pain and a burning sensation.

Later, symptoms of widespread poisoning may begin to appear, including:

  • Pale skin and sweating.

  • Confusion.

  • Eventual loss of consciousness.

Blood pressure may fall, causing shock. Major organs may be affected, possibly resulting in respiratory failure and acute heart failure.

Most scorpion stings are extremely painful but otherwise harmless. However, a sting from a bark scorpion, which is found in parts of America, may cause further symptoms, including sweating, restlessness, vomiting, diarrhoea, an irregular heartbeat, and muscle spasms.

The bite of a venomous spider, such as the black widow spider, usually causes generalized muscle pain, sweating, and headache and may lead to shock.

Stings by marine creatures may produce pain and swelling. Raised, red, itchy areas of skin may appear at the point of contact with a jellyfish or sea anemone. Rarely, stings from marine animals may result in symptoms such as diarrhoea, vomiting, and an irregular heartbeat.

In addition, any poisonous bite or sting may cause a life-threatening anaphylactic reaction in susceptible people (see Anaphylaxis).

What can I do?

Call an ambulance. If a person is bitten by a snake or poisonous spider, remove any clothing or jewellery that may cause constriction if the area around the bite starts to swell. The person should move as little as possible. If a person has been bitten by a snake, note its appearance so that when you reach hospital the doctor can decide if antivenom is required.

Most scorpion stings need only application of a cold compress to the wound and painkillers for pain.

If a person has been stung by a marine animal, wipe off any stingers or tentacles and wash the area with sea water before seeking medical attention.

What might the doctor do?

Hospital treatment for a snake bite may include resuscitation and intravenous fluids. You may also be given antivenom, and antianxiety drugs may be helpful if you are panicking. Once your condition has stabilized, the affected area will be elevated and immobilized until the swelling subsides.

Treatment for a spider bite, or for a sting by a scorpion or marine animal, depends on the symptoms. Oxygen may be given for breathing difficulties. If the symptoms are severe, antivenom may be given to counteract the effects of the poison. Antivenoms are available for some scorpion stings and for the more dangerous species of poisonous marine animal. Pain can be relieved by applying a local anaesthetic to the skin.

With the appropriate treatment, most symptoms improve within a few days and there are no long-lasting effects.

Self-help: Avoiding Bites and Stings

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

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