In many homes across the United States, a familiar bottle sits quietly in the medicine cabinet, often used when pain or sleeplessness begins to interfere with a good night’s rest. For countless people, reaching for a nighttime pain reliever feels routine and harmless. One of the most commonly used options is Tylenol PM, a medication designed to relieve pain while helping people fall asleep. Because it is sold over the counter and has been widely trusted for years, many individuals assume it carries very little risk. However, some healthcare professionals are beginning to warn that the medication may not be as harmless as people think, especially when used frequently. Among those raising concerns is pharmacist Dr. Ethan Melillo, who has spoken publicly about the potential dangers of relying on Tylenol PM too often. His message is not that the medication should never be used, but rather that people often underestimate its strength and the effects it may have on the body over time. When used casually night after night, the ingredients in the medication can place unexpected stress on certain organs and body systems, making it important for people to understand exactly what they are taking.

A key issue with Tylenol PM is that it contains two active ingredients rather than just one. The first ingredient is acetaminophen, a pain reliever and fever reducer that is commonly found in many medications used to treat headaches, colds, and other minor conditions. The second ingredient is diphenhydramine, an antihistamine typically used to treat allergy symptoms but also known for its strong sedative effects. When these two ingredients are combined, they create a medication that both reduces pain and causes drowsiness, making it appealing for people who struggle to sleep because of discomfort. On the surface, this combination appears convenient and effective. A person can take one pill to ease aches while also helping the body relax into sleep. However, healthcare professionals warn that using this combination too often may expose the body to side effects associated with both ingredients. Regular use, especially without medical supervision, can cause the body to process these substances repeatedly, which may gradually create health concerns that many users never anticipate.

One of the most significant concerns involves how acetaminophen is processed in the body. After it is swallowed, acetaminophen travels to the liver, where it is broken down into several compounds. During this process, the body produces a small but potentially dangerous byproduct known as NAPQI. Under normal conditions, the body protects itself by neutralizing this toxin with a powerful antioxidant called glutathione. When glutathione levels are sufficient, the toxic compound is safely eliminated before it can harm liver cells. The problem occurs when the liver is overwhelmed. Taking large amounts of acetaminophen, using it repeatedly over long periods, or combining it with alcohol can reduce glutathione levels. When the protective system becomes depleted, NAPQI can begin to accumulate in the liver, damaging cells and potentially leading to severe liver injury. In extreme cases, this damage can result in liver failure. Health experts generally recommend that adults do not exceed about 4,000 milligrams of acetaminophen per day. However, because the drug appears in many cold and flu products, pain relievers, and sleep medications, some people unknowingly consume more than the safe limit.

Another reason experts urge caution is the increasing number of people living with liver conditions. Medical estimates suggest that more than 100 million Americans may have some form of liver disease, whether diagnosed or not. For individuals with compromised liver function, medications that rely on the liver for processing can place additional strain on the organ. Recognizing these risks, the U.S. Food and Drug Administration (FDA) introduced safety recommendations in 2011 aimed at reducing the amount of acetaminophen in combination medications. Regulators advised manufacturers to limit many products to 325 milligrams per tablet, because research indicated that higher doses did not significantly improve pain relief but did increase the risk of liver damage. Even with these guidelines, some formulations of Tylenol PM still contain relatively high doses of acetaminophen. This does not mean the medication is unsafe when taken correctly, but it highlights why users should pay careful attention to dosing instructions and avoid assuming that over-the-counter medicines are completely risk-free.

The second ingredient in Tylenol PM, diphenhydramine, also raises important health concerns when used regularly. Diphenhydramine belongs to a class of drugs known as anticholinergics, which work by blocking a neurotransmitter called acetylcholine in the brain and nervous system. This action helps reduce allergy symptoms and produces the sedative effect that makes people feel sleepy. However, blocking acetylcholine can also influence brain function in ways that may affect memory, thinking, and cognitive performance when the medication is used frequently. Some scientific studies have suggested that long-term use of anticholinergic medications may be associated with an increased risk of cognitive decline or dementia. Research has shown that individuals who used such medications daily for several years were significantly more likely to develop memory problems compared with those who used them occasionally. In addition to potential cognitive effects, diphenhydramine may cause side effects such as dry mouth, dizziness, confusion, blurred vision, and difficulty urinating. These symptoms can be particularly problematic for older adults, as they may increase the risk of falls, dehydration, and episodes of confusion or delirium.

Despite these concerns, medical experts are not suggesting that Tylenol PM should be removed from pharmacy shelves. When used occasionally and according to label instructions, it can still provide effective relief for temporary pain or short-term sleep problems. The key message from healthcare professionals like Dr. Melillo is that moderation and awareness are essential. Instead of relying on the medication every night, people who struggle with sleep are often encouraged to explore healthier long-term strategies. Improving sleep habits—such as maintaining a consistent bedtime schedule, limiting caffeine intake, reducing screen exposure before bed, and creating a relaxing nighttime routine—can often make a significant difference. In some cases, doctors may recommend behavioral therapy for insomnia or other medical treatments that address the underlying cause of sleep difficulties. Ultimately, the broader lesson is that even common medications deserve careful attention. Reading labels, understanding ingredients, and consulting healthcare professionals when needed can help individuals make safer choices about their health. While medicine cabinets offer quick solutions, long-term well-being often comes from informed decisions and responsible use of the medications we take.