The five major signs of poisoning are nausea and vomiting, confusion or altered consciousness, changes in breathing, changes in heart rate, and unusual physical marks like burns around the mouth or a chemical odor on the breath. These signs can appear within minutes or take hours to develop, depending on the substance and how much was consumed, inhaled, or absorbed through the skin.
Nausea, Vomiting, and Stomach Pain
Gastrointestinal distress is the most recognizable sign of poisoning and often the first to appear. When the body detects a harmful substance in the stomach, it tries to expel it. This can show up as sudden nausea, repeated vomiting, stomach cramps, or diarrhea. With some poisons, vomiting starts within 30 minutes. With others, especially certain bacteria or slower-acting chemicals, symptoms may not begin for hours or even days.
The severity matters. A single episode of nausea after accidentally swallowing a small amount of household cleaner is different from violent, repeated vomiting or bloody diarrhea. Bloody vomit or stool, in particular, signals that the substance is damaging the lining of the digestive tract. Persistent diarrhea combined with vomiting also raises the risk of dangerous dehydration, especially in young children and older adults.
Confusion and Altered Consciousness
Many poisons affect the brain directly. This can look like confusion, slurred speech, extreme drowsiness, agitation, hallucinations, or full loss of consciousness. In children, you might notice unusual sleepiness or hyperactivity that doesn’t match the situation. In adults, it can resemble intoxication: difficulty walking, uncoordinated movements, or an inability to answer simple questions.
Seizures are another neurological red flag. They can occur with exposure to certain pesticides, medications taken in overdose, and some industrial chemicals. Any sudden change in mental state without an obvious explanation, particularly in someone who may have had access to medications or chemicals, should be treated as a possible poisoning.
Changes in Breathing
Poisoning frequently disrupts normal breathing patterns. Depending on the substance, breathing may become dangerously slow and shallow or unusually rapid. Carbon monoxide poisoning, for example, typically causes shortness of breath along with headache and nausea. Inhaled chemical fumes can trigger coughing, wheezing, or a feeling of tightness in the chest. In severe cases, breathing may become gasping and irregular before stopping altogether.
Some substances cause fluid to build up in the lungs, making it progressively harder to breathe even after the person has been moved away from the source. If someone’s breathing sounds labored, unusually fast, or unusually slow after a possible exposure, that’s an emergency.
Changes in Heart Rate and Pupils
Your heart rate and pupil size are controlled by the same branch of the nervous system that many poisons target. A rapid heartbeat or a dangerously slow one can both indicate poisoning. You may notice the person’s pulse racing or, conversely, becoming faint and hard to detect.
Pupils offer another visible clue. Very large (dilated) pupils suggest exposure to one category of substances, while very small (constricted) pupils point to another. Either extreme, combined with other symptoms on this list, strengthens the suspicion of poisoning. A dry mouth or excessive drooling can accompany these changes, since the same nerve pathways control saliva production.
Visible Physical Signs
External clues are sometimes the most obvious indicators, especially when the person can’t communicate what happened. Burns or redness around the lips and mouth suggest that a corrosive substance was swallowed. Chemical stains on the skin, clothing, or the surrounding area tell you what the person may have been exposed to. A strange smell on the breath can also be telling: some poisons produce a distinctive chemical or fruity odor.
Skin color changes are another signal. A bluish tint, especially around the lips and fingertips, means the body isn’t getting enough oxygen. Flushing or an unusual redness can appear with other types of exposure. Look for empty pill bottles, open chemical containers, or scattered tablets nearby. These aren’t symptoms on the body, but they’re critical context that helps identify the substance and guide treatment.
What to Do if You Suspect Poisoning
Your response depends on how the person was exposed. If they swallowed something potentially toxic, do not try to induce vomiting unless specifically told to by a professional. If they inhaled a toxic substance, move them to fresh air immediately. If poison got on the skin, remove any contaminated clothing and rinse the area with running water for 15 to 20 minutes. For poison in the eyes, flush with running water for 15 to 20 minutes.
In any of these situations, call the Poison Help line at 1-800-222-1222. This toll-free number connects you to your local poison center from anywhere in the United States. Specialists there can walk you through what to do next based on the specific substance, the amount, and the person’s symptoms. If the person is unconscious, having seizures, or not breathing, call 911 first.
Try to have the container or product label available when you call. Knowing exactly what the person was exposed to, how much, and when it happened lets the poison center give the most accurate guidance. With children especially, acting quickly makes a significant difference in outcomes, even if you’re not completely sure a poisoning occurred.