There’s a familiar bottle sitting in countless medicine cabinets across the United States. Many people reach for it at night when pain, discomfort, or sleeplessness begins to interfere with rest. The label promises relief from aches and the ability to fall asleep faster, offering a simple solution for restless nights. The medication is Tylenol PM, and for millions of people it has become a routine part of nighttime habits. However, some healthcare professionals are raising concerns about how casually it is used. Among them is Dr. Ethan Melillo, a pharmacist who has spoken openly about the potential risks of taking this medication too frequently. His warning is not that the medicine never works, but that people often misunderstand how powerful it actually is. Because it is widely available over the counter and familiar to so many households, many assume it carries little risk. Yet repeated use—especially night after night—may place unexpected strain on the body. For that reason, experts say it is important to understand exactly what is inside the pills and how those ingredients affect the body over time.

One of the key concerns surrounding Tylenol PM is that it is not a single medication but a combination of two active ingredients that perform different functions. The first ingredient is Acetaminophen, a widely used pain reliever and fever reducer found in hundreds of medications. The second ingredient is Diphenhydramine, an antihistamine commonly used to treat allergies but also known for its sedating effect. Together, these two ingredients create a medication that both reduces pain and causes drowsiness, which is why many people use it as a nighttime sleep aid. At first glance, the combination seems convenient: relief from pain while helping the body drift into sleep. However, healthcare professionals warn that this convenience may also hide potential risks. When people rely on the medication regularly rather than occasionally, the body may experience side effects from both ingredients. Over time, repeated exposure can place stress on organs and systems that must process and eliminate these substances from the body.

One of the most significant concerns relates to how acetaminophen is processed by the body. When a person takes acetaminophen, the chemical is primarily broken down in the liver. During this process, the body produces a small amount of a toxic byproduct known as NAPQI. Under normal circumstances, the body neutralizes this toxin using a protective antioxidant called Glutathione. When adequate levels of glutathione are present, the toxin is safely removed before it can cause damage. The problem occurs when the liver becomes overwhelmed. Taking large doses of acetaminophen, combining it with alcohol, or using it repeatedly over long periods can deplete glutathione levels. When this happens, NAPQI may begin to accumulate and attack liver cells. In severe cases, this process can lead to significant liver injury and even life-threatening liver failure. Health experts generally consider about 4,000 milligrams of acetaminophen per day the maximum safe limit for most adults. However, because acetaminophen is found in many cold, flu, and pain medications, it can be surprisingly easy for people to exceed that limit without realizing it.

Another factor that increases concern is the growing prevalence of liver disease in the population. Health estimates suggest that more than 100 million Americans may live with some form of liver condition, whether diagnosed or undiagnosed. For these individuals, medications processed by the liver may create additional strain. Recognizing these risks, the U.S. Food and Drug Administration introduced recommendations in 2011 aimed at limiting the amount of acetaminophen in combination medications. Regulators encouraged manufacturers to restrict doses to 325 milligrams per tablet in many products because research showed that higher doses did not significantly increase pain relief but did increase the risk of liver damage. Despite those efforts, some formulations of Tylenol PM still contain higher amounts of acetaminophen. This does not mean the medication is unsafe when used correctly, but it highlights the importance of paying attention to dosage instructions. When people assume that over-the-counter drugs are harmless, they may take them more frequently than recommended, unknowingly exposing themselves to higher levels of risk.

The second ingredient, diphenhydramine, also raises important health considerations. This medication belongs to a group of drugs known as anticholinergics, which work by blocking the neurotransmitter acetylcholine in the brain and nervous system. While this mechanism helps reduce allergy symptoms and create a sedating effect, it may also influence memory, thinking, and cognitive function when used frequently. Some studies have suggested that long-term use of anticholinergic medications may be associated with an increased risk of cognitive decline and dementia. Research has shown that people who used these medications daily for several years had a significantly higher likelihood of developing memory problems later in life compared with those who used them only occasionally. In addition to potential cognitive effects, diphenhydramine can produce side effects such as dry mouth, dizziness, confusion, and urinary retention. These effects are particularly concerning for older adults, as they may increase the risk of falls, dehydration, or episodes of delirium. What may seem like a mild sleep aid can therefore carry consequences that are not immediately obvious.

Ultimately, medical experts are not suggesting that Tylenol PM should disappear from pharmacy shelves. When used occasionally and according to directions, it can still provide relief for short-term discomfort or temporary sleep disturbances. The key message from professionals like Dr. Melillo is moderation and awareness. If sleep problems occur frequently, healthcare providers often recommend exploring safer long-term solutions rather than relying on nightly medication. These may include improving sleep habits, reducing late-night screen exposure, limiting caffeine intake, maintaining a consistent bedtime routine, or discussing other treatment options with a doctor. Approaches such as behavioral therapy for insomnia or alternative pain management strategies may address the underlying cause of sleep disruption more effectively. The broader lesson is simple but important: even common medications deserve careful attention. Reading labels, understanding ingredients, and consulting healthcare professionals when necessary can help people make informed choices about their health. A medicine cabinet may offer quick solutions, but lasting well-being often begins with knowledge and thoughtful use of what we take.