What happens when you take thc with benzodiazepines?
Tetrahydrocannabinol (THC), the main psychoactive compound in cannabis, and benzodiazepines such as alprazolam, diazepam, lorazepam, clonazepam, and temazepam both calm the central nervous system. They reach that effect by different routes, but the routes converge, and combining them pushes the brain further in the same sedating direction than either does alone.
- Two depressant pathways meet. Benzodiazepines attach to the GABA-A receptor and strengthen the brain's main inhibitory (calming) signal. THC activates the CB1 cannabinoid receptor, which sits on many of the same circuits and dampens the release of excitatory signals. Both nudge brain activity downward.
- The sedation adds up. Taken together, the two produce more drowsiness, slower reaction time, unsteadiness, slurred speech, and gaps in memory than either alone. At higher exposure the depressant effect can extend to slowed, shallow breathing.
- The liver clears the benzodiazepine more slowly. Cannabinoids, especially CBD, can inhibit liver enzymes (notably CYP3A4) that break down several benzodiazepines. With those enzymes slowed, benzodiazepine levels can run higher and last longer than the prescribed dose alone would suggest.
Why is this important?
A benzodiazepine taken by itself is rarely fatal in an otherwise healthy adult. The danger climbs sharply when a second nervous-system depressant is added, and cannabis is one such depressant, alongside alcohol, opioids, and sedating antihistamines. Real-world poison-center and emergency data consistently show that serious benzodiazepine outcomes almost always involve a second substance.
Even short of an emergency, the combination is disabling. Both drugs blunt the formation of new memories, so people sometimes lose track of stretches of time. Unsteadiness raises the risk of falls, a particular concern for older adults. And the foggy, slowed feeling can linger into the next day, which makes driving and other safety-critical tasks unsafe.
A common but mistaken assumption is that being a regular cannabis user provides some protection. It does not. Tolerance to THC does not carry over to benzodiazepines, so the benzodiazepine's sedating effect is not blunted by frequent cannabis use.
What should you do?
The simplest and safest approach is not to use the two together. If you take a benzodiazepine, treat cannabis the way you would treat alcohol on that medication.
Before any change: Tell the clinician who prescribes your benzodiazepine that you use, or are considering, cannabis or THC products. Do not stop a benzodiazepine on your own, as stopping abruptly can be dangerous. Let your prescriber decide whether to adjust the plan, and review your full medication and cannabis use with your doctor or pharmacist.
Day to day: If both are part of your routine, keep them separate rather than stacking doses, never drive or operate machinery while affected by either, and avoid other depressants such as alcohol. Have someone able to check on you, especially when you are trying a new product or a stronger one.
After taking both: Skip driving, cycling, stairs in the dark, bathing, and cooking with open flames until you are fully clear. Seek emergency care right away for warning signs of dangerous depression: very slow or shallow breathing, blue or grey lips or fingertips, or someone who cannot be roused. In a suspected overdose, calling emergency services is the right move; the benzodiazepine reversal drug flumazenil can trigger seizures in long-term users and is not a do-it-yourself fix.
Which specific products are affected?
On the medication side, this applies across the benzodiazepine class, including alprazolam (Xanax), diazepam (Valium), lorazepam (Ativan), clonazepam (Klonopin), temazepam (Restoril), oxazepam (Serax), triazolam (Halcion), midazolam (Versed), chlordiazepoxide (Librium), and clobazam (Onfi). The closely related Z-drugs, zolpidem (Ambien), zaleplon (Sonata), and eszopiclone (Lunesta), act on the same GABA-A receptor and carry the same caution.
On the cannabis side, the caution covers all routes and product types: smoked or vaporized flower, hash, and concentrates; oral products such as gummies, baked goods, tinctures, and infused drinks; and prescription cannabinoid medicines such as dronabinol (Marinol, Syndros) and nabilone (Cesamet). Hemp-derived analogues like delta-8, delta-10, and HHC act on the same CB1 receptor and carry the same risk.
The science behind it
The additive central-nervous-system depression here rests on well-established pharmacology rather than on a single large trial of this exact pairing.
- Ho JJY, et al. Evaluation of potential drug-drug interactions with medical cannabis. Clin Transl Sci (2024). A review of cannabis drug-interaction evidence, including additive sedation with other CNS depressants and cannabinoid effects on drug-metabolizing enzymes. Read it here.
- Caicedo DA, et al. An Overview of the Potential for Pharmacokinetic Interactions Between Drugs and Cannabis Products in Humans. Pharmaceutics 2025;17(3):319. A review cataloguing how THC and CBD inhibit cytochrome P450 enzymes, including CYP3A4, which clears several benzodiazepines. Read it here.
- Cannabis with Benzodiazepines and Opioids: Compounded Risk. CannabisForSeniors.org. Clinical guidance describing the compounded sedation risk when cannabis is combined with benzodiazepines or opioids. Read it here.
Frequently Asked Questions
Is it ever safe to use cannabis while on a benzodiazepine?
The safest approach is to keep them separate, because both are nervous-system depressants and their effects add together. If both are genuinely part of your care, that should be managed and monitored by your prescriber rather than decided on your own.
Does CBD-only (no THC) carry the same risk?
CBD causes less direct sedation than THC, but it is actually a stronger inhibitor of the liver enzymes that clear some benzodiazepines, so it can still raise benzodiazepine levels. It is worth telling your clinician about CBD use too.
My cannabis tolerance is high. Doesn't that protect me?
No. Tolerance to THC does not transfer to benzodiazepines. The benzodiazepine's sedating and breathing-slowing effects are not blunted by being a regular cannabis user.
What are the warning signs I should not ignore?
Very slow or shallow breathing, blue or grey lips or fingertips, severe confusion, or someone who cannot be woken. These call for emergency services right away.
Can I just take them a few hours apart?
Spacing them out reduces peak overlap but does not remove the risk, because benzodiazepines and cannabis can both linger for hours. Spacing is a harm-reduction step, not a green light, and it does not replace a conversation with your prescriber.
Should I stop my benzodiazepine if I want to use cannabis?
Never stop a benzodiazepine on your own, as abrupt withdrawal can be dangerous. Any change should be planned with the prescriber.
Key takeaways
- THC and benzodiazepines both depress the central nervous system, so combining them adds up to stronger sedation, impaired coordination, memory gaps, and slowed breathing.
- Cannabinoids, especially CBD, can slow the liver enzymes that clear several benzodiazepines, raising and prolonging their effect.
- A high cannabis tolerance does not protect against a benzodiazepine's effects.
- Do not drive or operate machinery while affected by either, and seek emergency care for very slow or shallow breathing or unresponsiveness.
- Never stop a benzodiazepine abruptly; review your full medication and cannabis use with your doctor or pharmacist.