It’s the small blue bottle millions of Americans keep within arm’s reach.

The one they trust to ease pain, calm restless nights, and help them finally sleep.

But according to one pharmacist, that sense of safety may be dangerously misleading.

Dr. Ethan Melillo, a Rhode Island–based pharmacist, has gone public with a warning that’s made many people rethink what’s in their medicine cabinets. His concern? Tylenol PM — a product so familiar that most people never question it.

“I worry about how casually people use it,” he says. “Not because it doesn’t work—but because they don’t realize what it’s doing inside their bodies.”

A “Simple” Pill With a Complicated Risk

Tylenol PM isn’t just one medication. It’s two powerful drugs combined:

• Acetaminophen, a pain reliever
• Diphenhydramine, an antihistamine that causes drowsiness

Together, they promise pain relief and sleep. But according to Dr. Melillo, that convenience can quietly become dangerous—especially when used night after night.

The Liver Damage Most People Never See Coming

Acetaminophen is processed almost entirely by the liver. Under normal circumstances, your body can handle it.

But there’s a catch.

When acetaminophen breaks down, it produces a toxic byproduct called NAPQI. Your liver neutralizes it using a natural antioxidant called glutathione. As long as your body keeps up, damage is avoided.

The problem? That system has limits.

If you:

• Take too much acetaminophen in a short period

• Use it daily over long stretches

• Drink alcohol regularly

• Or already have liver stress

…the toxin begins to build.

When that happens, liver cells start dying—sometimes silently, until the damage becomes severe or even life-threatening.

The FDA warns that 4,000 mg per day is the upper safe limit for adults. That’s only eight Tylenol PM tablets—and many people unknowingly exceed that when they also take cold, flu, or pain medications containing acetaminophen.

A Hidden Risk for Millions

Health experts estimate that one in three Americans already has some degree of liver disease, often without symptoms.

That’s why, in 2011, the FDA urged manufacturers to reduce acetaminophen doses in combination drugs. Higher amounts didn’t improve pain relief—but they did increase the risk of liver injury.

Despite this, many nighttime pain relievers still contain high doses.

The Sleep Aid That May Harm the Brain

The second ingredient, diphenhydramine (the same drug found in Benadryl), creates the drowsy effect people rely on.

But it comes with a cost.

Diphenhydramine is an anticholinergic, meaning it blocks acetylcholine—a chemical essential for memory, focus, and cognitive health.

Studies have found that people who use anticholinergic medications long-term face up to a 54% higher risk of developing dementia.

Other side effects include:

• Confusion or brain fog

• Dizziness and falls

• Dry mouth and dehydration

• Urinary retention, especially in older adults

Dr. Melillo warns that while these symptoms may seem minor at first, they can quietly snowball—especially in aging adults.

The Takeaway

Tylenol PM isn’t inherently dangerous—but treating it like a harmless sleep aid can be.

Dr. Melillo’s message is simple:
Know what you’re taking. Know how often. And don’t assume “over-the-counter” means “risk-free.”

Sometimes, the most familiar medicines are the ones we should question the most.

Tylenol PM and Riskier Choices?

Here’s a surprising twist: acetaminophen may influence more than just physical pain—it may also affect how you think and make decisions.

In a 2020 study from Ohio State University, researchers gave participants either 1,000 milligrams of acetaminophen or a placebo. They were then asked to evaluate how risky various activities seemed, ranging from skydiving and bungee jumping to major life choices like changing careers.

The results were unexpected. Those who took acetaminophen consistently rated these activities as less risky than those who hadn’t taken the drug. Researchers believe the medication may blunt emotional responses, reducing feelings such as fear, anxiety, and even excitement.

Earlier studies support this idea, showing that acetaminophen can dampen empathy—making people less sensitive to others’ pain—and can also mute positive emotions like happiness.

In other words, this common medication may do more than relieve discomfort or help with sleep. It may subtly influence how you perceive risk, emotion, and the world around you.

So What Should You Do Instead?

Dr. Melillo isn’t calling for Tylenol PM to be pulled from shelves. He acknowledges that it can be helpful when used occasionally. But he strongly cautions against making it a nightly habit.

For ongoing sleep issues, he recommends talking with a healthcare professional about alternatives, such as:

• Sleep aids that don’t create dependence

• Melatonin or other natural supplements

• Improving sleep hygiene—reducing screen time, avoiding caffeine later in the day, and keeping a consistent bedtime

• Cognitive Behavioral Therapy for Insomnia (CBT-I), which research shows can be more effective long-term than medication

  

If pain is the main issue, he suggests options like:

• Using acetaminophen only when truly necessary

• Rotating pain relievers instead of relying on one consistently

• Exploring non-drug approaches such as heat therapy, gentle stretching, or massage

The goal isn’t to eliminate relief—it’s to avoid creating new problems while solving old ones.

The Bottom Line

Tylenol PM may seem like an easy solution for pain or sleepless nights, but the full picture is more complex.

The potential risks—liver strain, cognitive changes, emotional blunting, and possible links to dementia—become more concerning with frequent use. That’s why Dr. Melillo urges caution and awareness.

As he puts it:

“If you’re taking it once in a while, that’s usually fine. But it shouldn’t be your nightly routine. Long-term use can come with consequences.”

Your medicine cabinet may look harmless—but informed choices matter. Sometimes the smartest health decision isn’t about what helps you sleep tonight, but what protects your well-being in the long run.