Unisom is a popular OTC sleep aid available in two formulations with different active ingredients. Unisom for sleep uses sedating antihistamines that work but have limitations for chronic use.
Two formulations
Unisom SleepTabs (doxylamine succinate, 25 mg):
- Original Unisom
- Sedating antihistamine
- Half-life: 10 hours (longer than diphenhydramine)
- More likely to cause morning grogginess
- Used for pregnancy nausea (Diclegis)
Unisom SleepGels/SleepMelts (diphenhydramine, 25-50 mg):
- Same active ingredient as Benadryl
- Half-life: 4-8 hours
- Less morning grogginess but possible
Effectiveness
- Reduce sleep onset modestly
- Tolerance develops quickly with regular use
- Effects diminish within 1-2 weeks of regular use
- Not appropriate for chronic insomnia
Side effects
- Morning grogginess
- Dry mouth
- Constipation
- Urinary retention
- Cognitive effects (especially in elderly)
- Anticholinergic burden (concerning for older adults)
The elderly concern
Diphenhydramine particularly problematic for older adults:
- Falls risk
- Cognitive impairment
- Anticholinergic effects accumulate
- Beers Criteria identifies as inappropriate for elderly
Pregnancy use
Doxylamine has substantial pregnancy data and is used for morning sickness. Generally considered acceptable in pregnancy when needed.
Frequently Asked Questions
Which Unisom is better for sleep?
Doxylamine more sedating but more morning grogginess. Diphenhydramine shorter duration.
Can I take Unisom every night?
Tolerance develops. Not appropriate for chronic insomnia.
Is Unisom safe in pregnancy?
Doxylamine has pregnancy data; sometimes used for morning sickness.
Why shouldn’t elderly take Benadryl/Unisom?
Anticholinergic side effects, falls risk, cognitive impairment.
Will Unisom show on drug test?
Diphenhydramine can occasionally cause false positive for some drugs.
The bottom line on Unisom
OTC sleep aid effective short-term but limited for chronic use. Both formulations have side effects. Consider CBT-I for chronic insomnia.