Across the United States, a familiar bottle sits in many medicine cabinets. When pain, discomfort, or sleeplessness strikes at night, countless people turn to it for relief. The label promises help with pain while making it easier to fall asleep, which is why Tylenol PM has become a common part of many bedtime routines. However, some healthcare professionals are beginning to warn that this casual, frequent use may not be as harmless as people think. Pharmacist Ethan Melillo has spoken publicly about the potential dangers of relying too heavily on this medication.

His concern isn’t that the drug is ineffective, but that many people underestimate how powerful it can be. Because it’s sold over the counter and widely trusted, people often assume it carries very little risk. In reality, using it regularly—especially night after night—may place unexpected stress on the body. Experts emphasize that understanding the ingredients and how they affect the body over time is essential for safe use.

One important detail is that Tylenol PM isn’t a single medication but a combination of two active ingredients. The first is Acetaminophen, a common pain reliever and fever reducer found in many medicines. The second is Diphenhydramine, an antihistamine typically used for allergies that also causes drowsiness. Together, they reduce pain while helping the body relax enough to sleep. While this combination can be helpful for short-term relief, health professionals say frequent use may expose the body to side effects from both components.

One of the biggest concerns involves how acetaminophen is processed. The liver breaks it down and produces a small amount of a toxic byproduct called NAPQI. Normally, the body neutralizes this toxin with an antioxidant known as Glutathione. When glutathione levels are sufficient, the toxin is safely eliminated. Problems can arise if the liver becomes overloaded—such as when large doses are taken, when alcohol is consumed alongside the drug, or when it’s used repeatedly over long periods. In those situations, NAPQI can build up and damage liver cells, potentially leading to serious liver injury or even liver failure.

Health experts generally consider about 4,000 milligrams of acetaminophen per day the upper safe limit for most adults. However, since acetaminophen is included in many cold, flu, and pain medications, people can accidentally exceed that amount without realizing it. This risk is especially concerning because millions of Americans already live with some form of liver disease, whether diagnosed or not.

To address these concerns, the U.S. Food and Drug Administration introduced recommendations in 2011 encouraging manufacturers to limit acetaminophen doses in combination medicines to 325 milligrams per tablet. Research suggested that higher doses did not significantly improve pain relief but did increase the risk of liver damage. Even so, certain formulations still contain higher amounts, making it important for consumers to carefully read labels and follow dosing instructions.

The second ingredient, diphenhydramine, also raises questions among health experts. This drug belongs to a class known as anticholinergic drugs, which work by blocking the neurotransmitter acetylcholine in the nervous system. While this action helps reduce allergy symptoms and promote sleep, long-term or frequent use may affect memory and cognitive function. Some research suggests that prolonged use of anticholinergic medications may be associated with a higher risk of cognitive decline or dementia.

In addition, diphenhydramine can cause side effects such as dry mouth, dizziness, confusion, and difficulty urinating. These effects can be especially risky for older adults, increasing the chance of falls, dehydration, or episodes of confusion. What seems like a mild nighttime sleep aid may therefore carry consequences that are not immediately obvious.

Medical professionals are not suggesting that Tylenol PM should disappear from pharmacy shelves. When used occasionally and exactly as directed, it can still help relieve temporary pain and sleep disturbances. The key message from experts like Dr. Melillo is moderation and awareness.

For people who struggle with sleep regularly, doctors often recommend safer long-term solutions instead of relying on medication every night. Improving sleep habits—such as reducing late-night screen use, limiting caffeine, maintaining a consistent bedtime routine, and practicing better sleep hygiene—can often make a significant difference. In some cases, treatments like behavioral therapy for insomnia or alternative pain management strategies may address the root of the problem more effectively.

The broader lesson is simple: even common over-the-counter medicines deserve careful attention. Reading labels, understanding ingredients, and seeking professional guidance when necessary can help people make safer decisions. A quick solution in the medicine cabinet may offer temporary relief, but long-term health depends on informed and thoughtful use.