The signs and symptoms seen in poisoning are so wide and variable that there is no easy way to classify them.
- Some poisons enlarge the pupils, while others shrink them.
- Some result in excessive drooling, while others dry the mouth and skin.
- Some speed the heart, while others slow the heart.
- Some increase the breathing rate, while others slow it.
- Some cause pain, while others are painless.
- Some cause hyperactivity, while others cause drowsiness. Confusion is often seen with these symptoms.
When the cause of the poisoning is unknown
A big part of figuring out what type of poisoning has occurred is connecting the signs and symptoms to each other, and to additional available information.
- Two different poisons, for example, may make the heart beat quickly. However, only one of them may cause the skin and mouth to be very dry. This simple distinction may help narrow the possibilities.
- If more than one person has the same signs and symptoms, and they have a common exposure source, such as contaminated food, water, or workplace environment, then poisoning would be suspected.
- When two or more poisons act together, they may cause signs and symptoms not typical of any single poison.
Certain poisons cause what toxicologists call toxidromes - a contraction of the words toxic and syndrome. Toxidromes consist of groups of signs and symptoms found together with a given type of poisoning.
- For example: Jimson weed, a plant smoked or ingested for its hallucinogenic properties, produces the anticholinergic toxidrome: Rapid heart rate, large pupils, dry hot skin, retention of urine, mental confusion, hallucinations, and coma.
- Most poisons either have no associated toxidrome or have only some of the expected features of the toxidrome.
Delayed onset of symptoms
A person can be poisoned and not show symptoms for hours, days, or months. Cases of poisoning with a prolonged onset of symptoms are particularly dangerous because there may be a dangerous delay in obtaining medical attention.
- Acetaminophen (Tylenol) is considered one of the safest drugs but is toxic to the liver when taken in large quantities. Because it acts so slowly, 7-12 hours may pass before the first symptoms begin (no appetite when normally hungry, nausea, and vomiting).
- The classic example of a very slow poison is lead. Before 1970, most paints contained lead. Young children would eat paint chips and, after several months, develop abnormalities of the nervous system.