You've probably heard the urban legend. Someone wants to play a "prank" on a friend, so they slip a few drops of eye medication into their drink. The myth says it just causes a quick bout of diarrhea. Basically, a harmless way to get back at a roommate, right?
Wrong.
It’s actually incredibly dangerous. If you or someone you know is wondering what happens if you ingest Visine, the short answer is potential coma, respiratory failure, or a heart rate that drops so low it becomes life-threatening. This isn't a bathroom joke. It's a trip to the ICU.
The active ingredient in most redness-relief eye drops is a chemical called tetrahydrozoline. It belongs to a class of drugs known as imidazolines. When you put it in your eyes, it works by constricting the blood vessels on the surface of the eye (the conjunctiva). This reduces redness and makes your eyes look clear. It's great for allergies or a late night. But your stomach is not your eye.
The Chemistry of Why it Goes Wrong
Tetrahydrozoline is a potent vasoconstrictor. When it enters your digestive system, it doesn't stay there. It gets absorbed into your bloodstream and crosses the blood-brain barrier. Once it’s in your system, it acts as a central nervous system depressant. It basically tells your brain to slow everything down.
Your heart rate drops. This is called bradycardia. Your blood pressure might spike initially, but then it can crash dangerously low. Your body temperature starts to fall (hypothermia). In many cases, people become extremely lethargic or even fall into a deep, unresponsive sleep.
It’s Not Just "Bad Tummy" Issues
The "diarrhea prank" myth likely stems from a confusion with other substances, but there is zero medical evidence that Visine acts as a laxative. Instead, it acts like a sedative—but a toxic one.
Dr. Alfred Aleguas, the managing director of the Florida Poison Information Center, has gone on record multiple times debunking the idea that this is a harmless prank. He explains that even a small amount can cause significant central nervous system depression. We aren't talking about a bottle; we are talking about a few milliliters.
Think about the size of a standard Visine bottle. It's usually 15ml. If a toddler gets a hold of that and drinks even a quarter of it, they are in serious, immediate trouble. Even for a healthy adult, the "standard" prank dose of a few drops can be enough to trigger a visit to the emergency room.
Symptoms to Watch For
The onset can be surprisingly fast. Sometimes within 15 to 30 minutes.
First, the person might seem a little "off." Maybe they’re suddenly very sleepy. They might complain of a headache or feeling dizzy. But then it gets heavier. Their skin might get cold and clammy to the touch. Their breathing slows down. This is the scary part—respiratory depression. They might literally forget to breathe deeply enough to keep their oxygen levels up.
- Extreme drowsiness or inability to stay awake.
- Slow heart rate (you can feel their pulse—it’ll be weak and slow).
- Low body temperature (they’ll feel chilly even in a warm room).
- Blurred vision or dilated pupils.
- Nausea and vomiting (though not in the way the myths suggest).
If you see these signs after someone has accidentally or intentionally swallowed eye drops, don't wait. Don't "sleep it off." Call 911 or your local emergency services immediately.
Real World Consequences and Legal Reality
People have actually faced serious criminal charges for doing this. In 2020, a woman in South Carolina was charged after she allegedly put Visine in her husband’s water for days. He suffered for months with unexplained illnesses before the truth came out. This is considered poisoning. In the eyes of the law, it's often treated as assault with a deadly weapon or even attempted murder depending on the jurisdiction.
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It’s also important to note that many modern eye drops use different active ingredients, like brimonidine or oxymetazoline. These are also dangerous when swallowed. Basically, anything meant for the eye should never, ever be swallowed. The concentrations are meant for topical application only.
Why Kids are at the Highest Risk
The FDA has actually issued warnings specifically about these types of eye drops because of the risk to children. Because kids have much lower body mass, a tiny amount of tetrahydrozoline can be fatal. The bottles often don't have child-proof caps, which is a major safety gap.
If a child swallows Visine, their heart rate can plummet almost instantly. Poison control centers across the country handle thousands of cases of accidental ingestion of over-the-counter medications every year, and eye drops are a frequent culprit.
What Happens if You Ingest Visine: The Medical Treatment
If someone ends up in the ER after ingesting eye drops, there is no specific "antidote" that magically neutralizes the tetrahydrozoline. Doctors have to provide supportive care.
This usually involves:
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- Intravenous fluids to help stabilize blood pressure.
- Oxygen or a ventilator if the person’s breathing is too shallow.
- Monitoring the heart via EKG to ensure the heart rate doesn't drop to a point of cardiac arrest.
- Warming blankets to fight off the hypothermia caused by the drug.
Most people recover with proper medical help, but the window of time is tight. If someone is left alone to "sleep it off," they might stop breathing in their sleep.
Actionable Steps if Exposure Occurs
If you suspect someone has swallowed eye drops, follow these steps immediately. Do not guess.
1. Call Emergency Services or Poison Control.
In the U.S., you can reach Poison Control at 1-800-222-1222. Do this even if the person seems fine right now. The "crash" often happens suddenly after a short delay.
2. Identify the Bottle.
Find the exact brand and active ingredient. Look for "Tetrahydrozoline," "Naphazoline," or "Oxymetazoline." Having this information ready for the paramedics or the poison control operator can save precious minutes.
3. Do Not Induce Vomiting.
Unless a medical professional specifically tells you to, do not try to make the person throw up. This can lead to aspiration (getting the liquid in the lungs) or other complications, especially if the person is already becoming drowsy.
4. Stay with the Person.
Monitor their breathing and keep them awake if possible. If they lose consciousness, turn them onto their side (the recovery position) to keep their airway clear.
5. Secure Your Medications.
If you have these drops in your house, move them to a high shelf or a locked cabinet. Treat them with the same level of caution you would use for prescription painkillers or bleach. The "everyday" nature of Visine makes it easy to forget how potent the chemicals inside really are.
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Ingesting Visine is a serious medical event that requires professional intervention. The myths surrounding it are dangerous, and the physical reality of how it affects the heart and brain is a stark reminder that "over-the-counter" does not mean "harmless."