Yes, drinking eye drops can kill you. The active ingredients in common redness-relief eye drops cause dangerous drops in heart rate, blood pressure, and breathing when swallowed, and multiple deaths have been documented. This is not a harmless prank or a way to cause an upset stomach. It is a genuine poisoning risk.
Why Eye Drops Are Dangerous to Swallow
Most over-the-counter redness-relief eye drops contain one of three active ingredients: tetrahydrozoline, oxymetazoline, or naphazoline. These belong to a drug class called imidazolines. When applied to the eye in tiny amounts, they constrict blood vessels on the eye’s surface, reducing redness. When swallowed, they enter the bloodstream in much larger quantities and cross into the brain, where they suppress the body’s “fight or flight” nervous system.
The result is that blood pressure plummets, heart rate slows dramatically, and the brain’s drive to breathe can weaken or shut down. The FDA has issued a safety communication warning that serious harm can result from accidentally swallowing these products, particularly in young children five and under.
The Diarrhea Myth
A persistent myth, popularized by movies and internet folklore, claims that slipping eye drops into someone’s drink causes uncontrollable diarrhea. This is dangerously wrong. Diarrhea is not a common effect of swallowing tetrahydrozoline. What actually happens is far more serious: sleepiness, dangerously low blood pressure, and a slow heart rate that can become life-threatening. Teenagers and adults who drink larger amounts can develop abnormal heart rhythms and breathing problems. Putting eye drops in someone’s drink is not a joke. It is poisoning, and people have been criminally charged for it.
What Happens to the Body
Symptoms typically begin within minutes of ingestion. In one documented case of a child who swallowed tetrahydrozoline, he became pale and fatigued within minutes, followed by sweating and then sleepiness. The full range of toxic effects generally appears within 15 minutes to 4 hours after swallowing.
The key symptoms include:
- Dangerously slow heart rate (bradycardia)
- Low blood pressure, sometimes severe enough to cause loss of consciousness
- Depressed breathing, which in serious cases can require a ventilator
- Hypothermia, where body temperature drops and may stay low for up to 24 hours
- Drowsiness progressing to unresponsiveness
Because tetrahydrozoline has a relatively short half-life of about 1 to 4 hours, most poisoning cases resolve within 24 hours with medical support. However, cardiovascular effects can linger for up to 36 hours. In the pediatric case described above, vital signs returned to normal around 12 hours after ingestion, and the child was discharged the following day with no lasting effects. That outcome, though, depended on prompt hospital care.
How Much Is Dangerous
There is no well-established lethal dose for tetrahydrozoline in humans, partly because fatal cases are relatively rare and involve varying circumstances. What is clear is that very small volumes can cause serious toxicity, especially in children. A toddler who swallowed just 5 mL (about one teaspoon) of a similar imidazoline eye drop developed a dangerously slow heart rate and repeated episodes where breathing stopped entirely.
For adults, the volume needed to cause harm is larger but still well within the range of a single bottle. A standard bottle of redness-relief eye drops contains 15 to 30 mL. Drinking a significant portion of one bottle could produce serious cardiovascular and respiratory depression in an adult.
Documented Deaths
Deaths from eye drop ingestion are uncommon but real. A forensic review published in Forensic Science, Medicine, and Pathology examined 129 cases that tested positive for tetrahydrozoline at a reference toxicology laboratory. Among the postmortem cases, the documented circumstances included homicides, suicides, a sudden death, and suspected poisonings. In one case, a death originally attributed to natural causes was later linked to tetrahydrozoline after toxicology testing found the compound in the deceased’s blood at 68 nanograms per milliliter. The study’s authors noted that tetrahydrozoline has appeared in multiple homicide, suicide, and drug-facilitated crime cases, underscoring why forensic labs now include it in comprehensive testing panels.
Children Face the Highest Risk
Young children are especially vulnerable because their small body weight means even a few swallows can deliver a proportionally massive dose. The FDA’s review focused on children five and under, where accidental ingestion has led to hospitalization, intensive care, and mechanical ventilation. Since 2013, the Consumer Product Safety Commission has required child-resistant packaging on any product containing 0.08 milligrams or more of an imidazoline in a single package. That rule covers tetrahydrozoline, naphazoline, oxymetazoline, and xylometazoline products. If you have young children at home, store eye drops and nasal sprays out of reach, just as you would with any medication.
What Treatment Looks Like
There is no specific antidote for imidazoline poisoning. Treatment in a hospital is supportive, meaning the medical team monitors and stabilizes heart rate, blood pressure, and breathing until the drug clears the body. In severe cases, that can mean IV fluids to raise blood pressure and a ventilator to assist breathing. Most patients recover fully within 24 to 48 hours if they receive timely care. In the pediatric case study from the Turkish Journal of Pediatrics, a one-week follow-up found the child completely healthy with no lingering symptoms.
If you suspect someone has swallowed eye drops, call Poison Control (1-800-222-1222 in the U.S.) or emergency services immediately. Do not wait for symptoms to appear. The window between ingestion and serious cardiovascular depression can be very short.