ZzzQuil is an over-the-counter sleep aid whose primary active ingredient is diphenhydramine¹². Diphenhydramine is a first-generation antihistamine commonly used to relieve symptoms of allergy, hay fever, and the common cold, such as runny nose, sneezing, and itchy or watery eyes³. Beyond its use for allergy relief, diphenhydramine is also employed to treat insomnia due to its sedative properties⁴.

Here are some key points about ZzzQuil and diphenhydramine:

• Mechanism of Action: ZzzQuil uses diphenhydramine, which works by blocking histamine, a substance in the body that causes allergic symptoms. This antihistamine effect also leads to drowsiness, aiding in sleep initiation⁵.
• Usage: It's typically taken 30 minutes before bedtime to help with occasional sleeplessness⁶.
• Formulations: Diphenhydramine is available in various forms such as tablets, liquid-filled capsules, and liquid. ZzzQuil comes in liquid and liqui-cap forms⁷.
• Safety: While generally safe for short-term use, diphenhydramine can pose risks, especially with long-term use or in older adults, including potential motor impairment and anticholinergic effects. It should not be used to induce sleep in children⁸⁹.

If you need more specific product recommendations, feel free to ask!

Footnotes

1. MedlinePlus on Diphenhydramine ↩

2. Gerontological Society of America Workgroup on OTC Sleep Aids ↩

3. NCBI Bookshelf on Diphenhydramine ↩

4. StatPearls on Diphenhydramine ↩

5. StatPearls on Diphenhydramine ↩

6. NCBI Bookshelf on Diphenhydramine ↩

7. MedlinePlus on Diphenhydramine ↩

8. NCBI Bookshelf on OTC Products ↩

9. Gerontological Society of America Workgroup on OTC Sleep Aids ↩