NutriStack
Melatonin and Quetiapine, a caution.
Both quetiapine and melatonin have sedative properties, and their combination produces additive CNS depression. Quetiapine is particularly sedating among antipsychotics due to potent histamine H1 receptor antagonism. Adding melatonin may cause excessive drowsiness, impaired cognitive function, and motor coordination problems, especially in elderly patients. However, in some clinical contexts (e.g., managing sundowning in delirium), the combination may be therapeutically beneficial.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Melatonin and Quetiapine
- Pair type
- Caution
- Evidence (highest tier)
- Moderate
- Source citations
- 4 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Caution · Moderate evidence
Caution
What is happening. Both quetiapine and melatonin have sedative properties, and their combination produces additive CNS depression. Quetiapine is particularly sedating among antipsychotics due to potent histamine H1 receptor antagonism. Adding melatonin may cause excessive drowsiness, impaired cognitive function, and motor coordination problems, especially in elderly patients. However, in some clinical contexts (e.g., managing sundowning in delirium), the combination may be therapeutically beneficial.
Mechanism. Quetiapine produces sedation primarily through histamine H1 receptor antagonism, with additional contributions from alpha-1 adrenergic and muscarinic receptor blockade. Melatonin activates MT1 and MT2 receptors in the suprachiasmatic nucleus, promoting sleep. The additive CNS depressant effects can impair alertness, cognition, and psychomotor function.
Recommendation. If using melatonin with quetiapine, start with the lowest melatonin dose (0.5-1 mg) and take both at bedtime. Avoid driving or operating machinery. Be especially cautious if elderly or taking other CNS depressants. Report excessive daytime drowsiness, confusion, or coordination problems to your prescriber.
Sources (4)
- Hatta K et al. Adjunctive treatment with melatonin receptor agonists for older delirious patients with the sundowning phenomenon. J Clin Psychopharmacol. 2015;35(2):191-194. PMID 25594519
- Fatemeh G, Sajjad M, Niloufar R et al.. Effect of melatonin supplementation on sleep quality: a systematic review and meta-analysis of randomized controlled trials.. Journal of Neurology. 2022. PMID 33417003
- Tang BHY, Manalo J, Chowdhury SR et al.. Melatonin Use in the ICU: A Systematic Review and Meta-Analysis.. Critical Care Medicine. 2025. PMID 40662882
- Chan V, Lo K. Efficacy of dietary supplements on improving sleep quality: a systematic review and meta-analysis.. Postgraduate Medical Journal. 2022. PMID 33441476
Stack Score
How this pair moves the number.
Effect on the composite score
If both Melatonin and Quetiapine are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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