Concurrent Use of Doxylamine (Unisom) and Hydroxyzine for Insomnia
Taking Unisom (doxylamine) and hydroxyzine together for insomnia is not recommended due to the increased risk of excessive sedation, anticholinergic side effects, and potential for cognitive impairment, especially in older adults. 1
Risks of Combining Antihistamines
Both doxylamine and hydroxyzine are first-generation antihistamines with significant sedating properties. Using them together presents several concerns:
- Additive sedation effects: Both medications cause drowsiness through similar mechanisms, potentially leading to excessive sedation
- Anticholinergic burden: Both drugs have anticholinergic properties that can cause:
- Dry mouth
- Blurred vision
- Urinary retention
- Constipation
- Cognitive impairment
- Increased fall risk: Particularly concerning for elderly patients 1
- Daytime somnolence: Research shows that sedating antihistamines like hydroxyzine can significantly increase daytime drowsiness 2
Evidence Against This Combination
The American Academy of Sleep Medicine specifically does not recommend diphenhydramine (which is pharmacologically similar to doxylamine) for sleep onset insomnia 1. While doxylamine has shown effectiveness for short-term insomnia treatment (up to four weeks), combining it with another antihistamine like hydroxyzine lacks supporting evidence 3.
Research has demonstrated that adding a sedating first-generation antihistamine at night does not improve sleep outcomes but does increase daytime somnolence 2. This suggests that combining two sedating antihistamines would likely produce similar negative effects without additional benefits.
Safer Alternatives for Insomnia
First-Line Non-Pharmacological Approaches
- Cognitive Behavioral Therapy for Insomnia (CBT-I) is recommended as first-line treatment for chronic insomnia 1
- Sleep restriction: Limiting time in bed to match actual sleep time
- Stimulus control: Reconditioning patients to associate bedroom with sleep
- Regular physical activity and morning exposure to bright light
- Sleep hygiene practices: Consistent sleep schedule, comfortable environment, limiting evening light exposure
Pharmacological Options (if non-pharmacological approaches fail)
For sleep onset insomnia:
- Zolpidem 10mg (adults), 5mg (elderly)
- Zaleplon 10mg
- Ramelteon 8mg 1
For sleep maintenance insomnia:
- Low-dose Doxepin (3-6 mg) - non-habit forming with minimal next-day sedation
- Eszopiclone 2-3mg
- Temazepam 15mg
- Suvorexant 10-20mg 1
Special Considerations
- Addiction potential: Case reports have documented doxylamine addiction, with patients escalating doses over time 4
- Elderly patients should receive lower doses of sedating medications due to increased fall risk 1
- Patients with respiratory conditions should avoid medications that can cause respiratory depression 1
Monitoring Recommendations
If medication is necessary for insomnia:
- Start with a single agent at the lowest effective dose
- Assess sleep parameters within 2-4 weeks of starting treatment
- Monitor for side effects, particularly daytime sedation, falls, and cognitive changes
- Schedule follow-up within 2-4 weeks to evaluate effectiveness 1
In conclusion, while both doxylamine and hydroxyzine are individually used for insomnia, combining them increases risks without proven additional benefits. Better alternatives exist for both short-term and chronic insomnia management.