Diphenhydramine: Sleep Fast, Side Effects Later
The second active ingredient in Tylenol PM is diphenhydramine, better known as Benadryl. This antihistamine is responsible for the sedative effect that helps you fall asleep. However, this drowsiness comes with trade-offs, especially when the drug is used regularly rather than occasionally.
While it may facilitate sleep in the short term, repeated use can have cognitive and neurological consequences that many users don’t anticipate.
Diphenhydramine belongs to a class of drugs known as anticholinergics, which means it interferes with acetylcholine, a chemical found in the brain. This substance plays a key role in memory, learning, and overall cognitive performance.
When acetylcholine is blocked too frequently or for long periods, problems can arise. Research has found that individuals who took anticholinergic drugs daily for three years or more had a 54% higher risk of developing dementia than those who used them only occasionally.
Diphenhydramine can also cause a number of side effects, including:
dry mouth
Dizziness or vertigo
Confusion, especially in the elderly
Urinary retention, which can lead to further complications in older adults
Dr. Melillo emphasizes that while these effects may seem mild on their own, they can trigger or worsen age-related problems, increasing the risk of falls, dehydration, and delirious episodes.
Tylenol PM and riskier choices?
Here’s an unexpected twist: acetaminophen can affect how you feel and how you assess risk.
In a 2020 study from Ohio State University, participants were given either 1,000 milligrams of acetaminophen or a placebo. They were then asked to rate the riskiness of various activities, from skydiving to bungee jumping to major life decisions like changing careers.
The results were surprising. Those taking paracetamol consistently rated these activities as less risky than participants who did not take the drug. The researchers suggest that the drug may blunt emotional reactions, reducing feelings such as fear and excitement.
Previous research supports this idea, showing that paracetamol can also reduce empathy, blunting emotional responses to others’ pain, and even dampening positive feelings like happiness.
