Can you take Benadryl with melatonin?
In most cases, Benadryl (diphenhydramine) and melatonin should not be taken together.
While they work differently mechanistically, they have a similar effect. Use of both together could potentially cause excess sedation, disrupt the sleep cycle and create additional sleep disturbances when used at the same time.
While we will discuss both drugs in more detail below, the key point is this:
Benadryl is a sedating, first-generation antihistamine.
It is well known to cause CNS (central nervous system) depression at usual doses of 25 mg to 50 mg.
Due to the sedative effects of the drug, it is very commonly used as an over the counter sleep aid. In fact, diphenhydramine (the active ingredient in Benadryl) is included in several OTC products, including ZzzQuil and Tylenol PM.
The onset of sedation is fairly quick, with maximum effects occurring 1 hour after administration.
The duration of action ranges based on the individual but generally lasts 4 to 8 hours.
When taking Benadryl as a sleep aid, it is important to get at least 8 hours of sleep, to reduce to risk of a 'hangover' effect.
Benadryl is well known to disrupt the sleep-wake cycle. Studies show that it can affect the time it takes to go to sleep, the amount of REM/non-REM sleep that occurs while you are sleep as well as the overall "feeling of rest" people experience.
A little known side effect of Benadryl is that it can sometimes cause a paradoxical reaction in people.
Instead of causing sedation, a small number of people can experience excitation, nervousness, and restlessness. This is much more common in doses exceeding 25 mg and in children versus adults.
Although they work via different mechanisms, melatonin and Benadryl are not recommended to be taken together.
The use of both together can cause additive CNS depression and sedation.
Some studies also show that the combination can increase the risk of a next day 'hangover' effect.
Lastly, both drugs have contradictory effects. Benadryl disrupts the sleep-wake cycle while melatonin promotes a return to a healthy sleep-wake cycle.
In general, Benadryl is best used intermittently to produce sedation for acute problems with insomnia.
Melatonin is best suited in those with low melatonin levels, or are in a situation in which their sleep-wake cycle is disrupted (e.g. due to jet lag or in night shift workers).
There are certainly some situations where taken both Benadryl and melatonin may be necessary (say for example you regularly take melatonin but need to use Benadryl to stem an allergic reaction), but be done consistently to help you sleep better.