From the manufacturer

Fast-acting solutions for occasional sleeplessness. ZzzQuil liquids are crafted by the experts at Vicks, a team with an unparalleled track record of providing innovative products to families like yours for over 125 years.

ZzzQuil is a safe and effective medication for treating short-term sleeping difficulties, or insomnia, in people over 12 years old. However, individuals with certain medical conditions, such asthma and heart disease, should speak to a doctor before taking ZzzQuil.

Don't take ZzzQuil every night. Talk with your doctor if you have questions about how long you can take ZzzQuil and at what dosage. In general, taking this medication only from time to time should keep side effects to a minimum. Talk to your doctor if you think this medication isn't helping you sleep.

Drowsiness, dizziness, constipation, stomach upset, blurred vision, or dry mouth/nose/throat may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly. To relieve dry mouth, suck (sugarless) hard candy or ice chips, chew (sugarless) gum, drink water, or use a saliva substitute.

4 to 8 years Drug free, non-habit forming, and tastes great! Children ages 4 to 8 years of age, give 1 gummy as needed 30 minutes before bedtime. For children ages 9 years of age and older, give 2 gummies as needed 30 minutes before bedtime. For best results, allow more than 6 hours of sleep.

Applies to diphenhydramine: oral capsules and tablets, parenteral injection. Side effects include: Sedation, sleepiness, dizziness, disturbed coordination, epigastric distress, thickening of bronchial secretions.

ZzzQuil liquid capsules help you fall asleep in as little as 20 minutes. ZzzQuil LiquiCaps contain a non-habit-forming ingredient, Diphenhydramine HCI, that helps you get the sleep you need. Each dose (two LiquiCaps) contains 50mg.

To summarize, melatonin is a safer choice to treat insomnia than Zzzquil or Tylenol PM. If your insomnia is more moderate, you may want to try Zzzquil, and if you're also dealing with acute pain or fever, then you may want to try Tylenol PM, but be careful to follow the directions and avoid overusing these drugs.

It is typically safe for adults to take melatonin every night for short periods of time.

“If melatonin for sleep isn't helping after a week or two, stop using it,” says Buenaver. “And if your sleep problems continue, talk with your health care provider. If melatonin does seem to help, it's safe for most people to take nightly for one to two months. “After that, stop and see how your sleep is,” he suggests.

Melatonin is generally safe for short-term use, but studies on its long-term effects are limited. The side effects of melatonin are typically mild. If you take melatonin and notice that it isn't helping you fall asleep or causes unwanted side effects, stop taking it and speak with your doctor.