The symptoms of poisoning depend on the substance and the amount that you take in.
Some poisonous substances, such as carbon monoxide, interfere with the blood's ability to carry oxygen. Others, such as bleach, burn and irritate the digestive system.
Parents and carers should be aware of sudden, unexplained illness in young children, particularly if they are drowsy or unconscious, as poisoning could be the cause.
If you suspect that someone has swallowed a poisonous substance, seek immediate medical advice. Read more about what to do if you think someone has been poisoned.
General symptoms
General symptoms of poisoning can include:
- feeling sick
- being sick
- diarrhoea
- stomach pain
- drowsiness, dizziness or weakness
- high temperature of 38°C (100.4°F) or above
- chills (shivering)
- loss of appetite
- headache
- irritability
- difficulty swallowing (dysphagia)
- producing more saliva than normal
- skin rash
- burns around the nose or mouth
- double or blurred vision
- seizures (fits)
- coma (in severe cases)
Symptoms of medication overdose
If you take a medication overdose, you may experience any of the specific symptoms below, as well as the more general symptoms above.
The most common medications involved in cases of poisoning are listed below.
Paracetamol
Paracetamol is a widely used over-the-counter painkiller.
Specific symptoms of paracetamol poisoning include:
- jaundice (yellowing of the skin and the whites of the eyes)
Aspirin
Aspirin was used as a painkiller in the past but is now increasingly used for its blood-thinning properties to prevent blood clots.
Specific symptoms of aspirin poisoning include:
- rapid breathing
- tinnitus (ringing in the ears)
Tricyclic antidepressants
Tricyclic antidepressants are used to treat depression as well as a number of other mental health conditions such as panic disorder and obsessive compulsive disorder (OCD). Some types of tricyclic antidepressants can also be used to treat nerve pain.
Specific symptoms of poisoning with tricyclic antidepressants include:
- excitability
- dry mouth
- large pupils
- irregular heartbeat
- low blood pressure
- a rapid heart rhythm
Selective serotonin reuptake inhibitors (SSRIs)
SSRIs are a newer type of antidepressant that are also used to treat a number of other mental health conditions such as OCD and anxiety disorder.
Specific symptoms of SSRI poisoning include:
- feeling agitated
- tremor (shaking)
- uncontrolled movement of the eyes (nystagmus)
In severe cases it can also cause:
Beta-blockers
Beta-blockers are used to treat a number of conditions that affect the heart or blood such as high blood pressure, angina and heart failure.
Specific symptoms of poisoning with beta-blockers include:
- low blood pressure
- a low pulse rate (below 60 beats a minute)
Calcium-channel blockers
Calcium-channel blockers are used in the treatment of high blood pressure and angina.
Specific symptoms of calcium-channel blocker poisoning include:
- chest pain
- low blood pressure
- a low pulse rate (below 60 beats a minute)
- blue skin
- breathing problems
Benzodiazepines
Benzodiazepines are a type of tranquiliser that are often used on a short-term basis to treat anxiety and sleeping problems (insomnia).
Specific symptoms of poisoning with benzodiazepines include:
- co-ordination and speech difficulties
- low blood pressure
- hypothermia (where body temperature drops below 35°C/95°F)
- shallow breathing
Opioids
Opioids are a type of stronger painkillers that are used to treat moderate to severe pain. Opioids include codeine and morphine as well as the illegal drug heroin.
Specific symptoms of opioid poisoning include:
- small pupils
- shallow breathing
- blue skin
- fluid on the lungs
Stimulant overdose
If you take too much of a stimulant-like drug such as cocaine, amphetamine, crack or ecstasy, overdose symptoms can include:
- anxiety and paranoia (feeling that people are out to get you)
- chest pain
- high temperature
- high blood pressure
- rapid breathing and heartbeat
- mental confusion
- hallucinations (seeing or hearing things that are not real)
- stomach cramps
Cannabis overdose
If you smoke (or eat) too much cannabis then you may experience the following symptoms:
- paranoia
- hallucinations
- numbness in your arms and legs
