Cannabis and Diazepam (Valium)
Brand names: Valium, Diastat, Valtoco
Important Medical Disclaimer
This information is for educational purposes only and does not constitute medical advice. Do not start, stop, or modify your use of Diazepam or cannabis without consulting your doctor or pharmacist. If you experience adverse effects, seek immediate medical attention. Individual responses to drug combinations vary significantly.
Overview
Diazepam is a long-acting benzodiazepine prescribed for anxiety, seizures, muscle spasms, and alcohol withdrawal. The combination of cannabis and diazepam is classified as high risk due to the convergence of two major concerns: significant pharmacokinetic interaction through shared metabolic pathways and dangerous pharmacodynamic additive sedation. Diazepam relies on both CYP3A4 and CYP2C19 for its metabolism — the same enzymes inhibited by CBD — meaning CBD can substantially increase diazepam blood levels while the two substances simultaneously amplify each other's sedative effects. The clinical danger is profound sedation that can impair breathing, particularly at higher doses. While benzodiazepines alone rarely cause fatal respiratory depression, the addition of other CNS depressants significantly increases this risk. Cannabis combined with diazepam can produce a level of sedation that makes it dangerous to perform any activity requiring alertness, and in extreme cases — especially when alcohol is also involved — can contribute to respiratory compromise. Diazepam's exceptionally long half-life (20-100 hours, with active metabolites lasting even longer) means the interaction window extends well beyond the acute effects of either substance.
How They Interact
Diazepam is metabolized by CYP3A4 to temazepam and by CYP2C19 to nordiazepam (desmethyldiazepam). Both metabolites are pharmacologically active, and nordiazepam has an extremely long half-life of 40-200 hours. CBD inhibits both CYP3A4 and CYP2C19, which can significantly slow the metabolism of diazepam and its active metabolites, leading to drug accumulation and prolonged effects. Pharmacodynamically, diazepam enhances GABAergic inhibition by binding to the benzodiazepine site on GABA-A receptors, while THC activates CB1 receptors that modulate GABA and glutamate signaling. Both pathways ultimately reduce central nervous system excitability, producing additive (and potentially synergistic) sedation, motor impairment, and cognitive suppression. The combination also increases the risk of anterograde amnesia — the inability to form new memories — which is already a known effect of both substances independently.
Cannabinoid-Specific Interactions
| Cannabinoid | Interaction with Diazepam |
|---|---|
| THC | THC and diazepam produce significant additive CNS depression through convergent GABAergic and endocannabinoid pathways. The combination dramatically amplifies sedation, impairs motor coordination and cognitive function, increases amnesia risk, and at high doses may contribute to dangerous respiratory depression. |
| CBD | CBD inhibits both CYP3A4 and CYP2C19, the two primary enzymes responsible for diazepam metabolism. This can substantially increase diazepam blood levels and extend the duration of its effects, compounding the sedative pharmacodynamic interaction. This dual metabolic and sedative interaction makes the combination particularly concerning. |
| CBN | CBN adds additional sedative effects to an already heavily sedating combination. The inclusion of CBN-containing products with diazepam and other cannabinoids creates a triple sedative burden that significantly increases the risk of excessive CNS depression. |
Symptoms to Watch For
- ⚠Profound drowsiness and difficulty maintaining consciousness
- ⚠Severe impairment of coordination, balance, and motor control
- ⚠Marked confusion, disorientation, and anterograde amnesia
- ⚠Slurred speech and slowed reflexes
- ⚠Respiratory depression in severe cases, particularly with high doses or additional CNS depressants
Recommendations
- 1Avoid combining cannabis with diazepam whenever possible. The interaction carries significant risk of dangerous sedation.
- 2If both substances are used, reduce the dose of each substantially and never add alcohol or other sedatives to the combination.
- 3Do not drive, operate machinery, or perform any task requiring alertness or coordination for the duration of effects — remember diazepam's active metabolites persist for days.
- 4CBD products should be avoided or used with extreme caution in patients on diazepam due to the significant pharmacokinetic interaction.
- 5Seek emergency medical attention if someone on this combination shows signs of respiratory depression: very slow or shallow breathing, bluish lips, or inability to be awakened.
Research Summary
The danger of combining benzodiazepines with other CNS depressants is extensively documented. The FDA issued a black box warning in 2016 about the risk of combining benzodiazepines with opioids, and similar pharmacodynamic principles apply to the cannabis-benzodiazepine combination. A 2019 study in the Journal of Clinical Pharmacology confirmed that CBD significantly inhibits CYP2C19, the enzyme responsible for diazepam's conversion to nordiazepam. The Epidiolex prescribing information warns about sedation when CBD is combined with CNS depressants, including benzodiazepines — in clinical trials, increased sedation was observed when Epidiolex was co-administered with clobazam (a related benzodiazepine). Pharmacokinetic studies have shown that CYP3A4 inhibitors can increase diazepam's AUC by 2-3 fold, and similar effects are plausible with CBD's CYP3A4 inhibition.
Frequently Asked Questions
Is it safe to smoke weed while taking Valium?
This is a high-risk combination. Both substances cause significant sedation, and cannabis (particularly CBD) can increase diazepam levels in your blood by inhibiting its metabolism. The result can be dangerous over-sedation, severe cognitive impairment, and in extreme cases, respiratory depression. This combination should be avoided or used only under close medical supervision with dose adjustments.
Can cannabis help me taper off benzodiazepines?
Some patients report that cannabis helps manage anxiety during benzodiazepine tapering, and a few observational studies have explored this. However, there is insufficient clinical evidence to recommend this approach, and combining the two during a taper carries interaction risks. Benzodiazepine tapering should always be done gradually under medical supervision.
How long does the interaction last with diazepam?
Diazepam has an extremely long effective duration due to its active metabolite nordiazepam, which has a half-life of 40-200 hours. This means the interaction with cannabis can persist for several days after a single diazepam dose. Even after the acute cannabis effects wear off, elevated diazepam levels from CYP inhibition may continue to cause enhanced sedation.
Is cannabis with Valium more dangerous than cannabis with Xanax?
Both combinations are high risk, but they differ in character. Diazepam has a longer duration and active metabolites that accumulate, while alprazolam (Xanax) has a shorter duration but is more potent per milligram. Both are metabolized by CYP3A4 (affected by CBD). The key message is that combining any benzodiazepine with cannabis carries significant risk and should be approached with extreme caution.