Diphenhydramine — a name you’ll find on countless pharmacy shelves under brand names like Benadryl, Unisom, and countless store-brand sleep aids. It’s been a go-to solution for allergies, seasonal sniffles, and sleepless nights for decades. Because it’s sold over the counter, many Americans assume it’s entirely safe to use as needed — even every night.
But here’s the truth: Diphenhydramine was never designed for long-term daily use.
Behind its familiar pink capsules lies a medication with side effects that can sneak up on you, especially when taken continuously over weeks, months, or even years. Whether you’re using it for chronic allergies or as a nightly sleep crutch, prolonged use carries risks that could affect both your physical and cognitive health.
In this article, we’ll dive deep into what diphenhydramine does, why people fall into the habit of using it long term, and — most importantly — the short-term and long-term side effects that every user should know.
