NutriStack
Alcohol and Guanfacine, a caution.
Guanfacine lowers sympathetic outflow and commonly causes sedation, fatigue, dizziness, bradycardia, and lower blood pressure. Alcohol can add CNS depression and worsen dizziness, slowed reaction time, orthostatic symptoms, and fainting risk. The combination is most concerning when starting guanfacine, increasing the dose, drinking heavily, or using other sedating substances.
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
- Alcohol and Guanfacine
- 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. Guanfacine lowers sympathetic outflow and commonly causes sedation, fatigue, dizziness, bradycardia, and lower blood pressure. Alcohol can add CNS depression and worsen dizziness, slowed reaction time, orthostatic symptoms, and fainting risk. The combination is most concerning when starting guanfacine, increasing the dose, drinking heavily, or using other sedating substances.
Mechanism. Guanfacine is a central alpha-2A adrenergic agonist that reduces sympathetic tone, lowering blood pressure and heart rate while causing sedation in some users. Alcohol adds pharmacodynamic CNS depression and can worsen postural instability and impaired coordination.
Recommendation. Avoid alcohol when starting guanfacine or after any dose increase. If you drink later in stable treatment, keep intake low and avoid driving, heat exposure, or standing quickly. Seek medical help for fainting, severe dizziness, very slow pulse, confusion, or repeated vomiting.
Sources (3)
- Sorkin EM, Heel RC. Guanfacine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in the treatment of hypertension. Drugs. 1986;31(4):301-336. PMID 3519177
- Magometschnigg D, Bonelli J, Gassner A, et al. Duration of the hypotensive effect of guanfacine. Int J Clin Pharmacol Ther Toxicol. 1982;20(4):174-178. PMID 7042594
- Weathermon R, Crabb DW. Alcohol and medication interactions. Alcohol Res Health. 1999;23(1):40-54. PMID 10890797
Stack Score
How this pair moves the number.
Effect on the composite score
If both Alcohol and Guanfacine 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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