NutriStack
Cannabis (THC-Dominant) and Hydroxyzine, a caution.
THC-dominant cannabis can compound hydroxyzine's sedating and attention-slowing effects. Hydroxyzine has measurable next-day and same-day cognitive effects in human studies, and THC acutely impairs psychomotor performance and driving-related skills. The combination is more concerning in people who are cannabis-naive, taking higher hydroxyzine doses, or using other sedatives.
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
- Cannabis (THC-Dominant) and Hydroxyzine
- Pair type
- Caution
- Evidence (highest tier)
- Moderate
- Source citations
- 3 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. THC-dominant cannabis can compound hydroxyzine's sedating and attention-slowing effects. Hydroxyzine has measurable next-day and same-day cognitive effects in human studies, and THC acutely impairs psychomotor performance and driving-related skills. The combination is more concerning in people who are cannabis-naive, taking higher hydroxyzine doses, or using other sedatives.
Mechanism. Hydroxyzine produces CNS sedation through central H1 receptor blockade. THC activates CB1 receptors and disrupts attention, divided-attention tracking, reaction time, and coordination, so effects on psychomotor performance can be additive.
Recommendation. Avoid combining THC-dominant cannabis with hydroxyzine when you need to be alert. If both were used, do not drive or do hazardous work until the effects have clearly worn off. Consider separating cannabis use from hydroxyzine therapy or using a less sedating allergy treatment if appropriate.
Sources (3)
- Kocis PT, Vrana KE. Delta-9-Tetrahydrocannabinol and Cannabidiol Drug-Drug Interactions. Med Cannabis Cannabinoids. 2020;3(1):61-73. PMID 34676340
- Conen S, Theunissen EL, Vermeeren A, Ramaekers JG. Short-term effects of morning versus evening dose of hydroxyzine 50 mg on cognition in healthy volunteers. J Clin Psychopharmacol. 2011;31(3):294-301. PMID 21508863
- Desrosiers NA, Ramaekers JG, Chauchard E, Gorelick DA, Huestis MA. Smoked cannabis' psychomotor and neurocognitive effects in occasional and frequent smokers. J Anal Toxicol. 2015;39(4):251-261. PMID 25745105
Stack Score
How this pair moves the number.
Effect on the composite score
If both Cannabis (THC-Dominant) and Hydroxyzine 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.
Check your full routine
One pair was the worked example. NutriStack runs every pair in your stack at once.
Drop in your supplements and prescriptions and the public database surfaces every interaction, synergy, timing rule, and contraindication, every one linked to its primary source.