Poisoning happens when you take into your body a substance that damages your cells and organs and injures your health.
Poisons are usually swallowed, but they can also be inhaled, splashed onto the skin or eyes, injected or received through a bite (as with snake bites).
Many substances are only poisonous if an abnormally large amount is taken. For example, paracetamol is harmless if you take one or two tablets for a headache, but is poisonous if you take an overdose.
Some substances are so toxic that small amounts can be harmful. For example, breathing in a small amount of carbon monoxide can cause loss of consciousness and death.
Poisoning accounts for more than 100,000 NHS hospital admissions in the UK each year.
Types of poison
There are lots of different poisonous substances, including medications, household products (such as cleaning products) and some plants and berries (see Causes for a summary of common poisons).
Substances that are not usually thought of as poisons, such as alcohol and tobacco, can also be very harmful.
Common cases
Most cases of poisoning are accidental and occur in the home. Children under five have the highest risk of accidental poisoning (see box, left), although these cases are rarely fatal. Medicines are the most common cause of poisoning in children of this age.
Occasionally, poisoning may be deliberate. For example, a person may attempt to poison themselves by taking an overdose of prescription medication. For more information, see Health A-Z: self-harm.
Outlook
Most cases of poisoning usually cause minor side effects, such as stomach upset, which settle within a few days. In these cases, hospital admission is not necessary.
People who develop serious symptoms, such as breathing problems or dizziness, or those who have taken a potentially life-threatening overdose of drugs such as painkillers, will need to go to hospital. Most of them will just be observed to make sure their condition does not get worse (see Treatment).
Fatal poisonings are extremely rare.
