At a Glance
- Caffeine is regularly consumed through coffee, tea, energy drinks, or other products. Therefore, many medical cannabis patients are exposed to the effects of cannabinoids and caffeine.
- Research suggests caffeine has little effect on how THC is processed by the body or on the intensity of its effects.
- Some studies have found that taking CBD and THC together may increase certain effects of THC, including feelings of euphoria.
- One small study found that caffeine did not significantly change how participants experienced CBD, although some people reported slightly more positive effects.
- More research is needed, but current evidence suggests that caffeine does not have a major impact on the effects of THC or CBD for most people.
Cannabis and Caffeine Together
As the use of medical cannabis continues to grow in the UK, many patients may have questions about how it interacts with other commonly consumed substances. Caffeine is one of the most widely used psychoactive compounds in the world and is found in everyday drinks such as coffee, tea and energy drinks.
Because caffeine and cannabinoids such as cannabidiol (CBD) and tetrahydrocannabinol (THC) may be consumed on the same day, researchers have become increasingly interested in how these compounds may interact. However, despite their widespread use, research in this area remains limited.
So, what is the relationship between CBD, THC and caffeine? And what can recent studies tell us about the potential effects of combining cannabis and coffee?
Cannabis, Caffeine and Oral Products
Many studies investigating cannabis and caffeine have focused on orally consumed products. This is because cannabinoids such as CBD and THC can be taken in formats including oils, capsules and other edible products, while caffeine is commonly consumed in drinks such as coffee, tea and energy drinks.
When cannabinoids are taken orally, their effects can take longer to develop than inhaled forms of cannabis. Understanding how caffeine may influence these effects could therefore be important for people who consume both substances on the same day.
Research Regarding Cannabis and Caffeine
Although cannabinoids and caffeine are commonly consumed, relatively little research has explored how these substances interact when taken together.
Early studies in animals suggested that caffeine may worsen some of the effects of THC on memory and cognitive performance. However, human research in this area remains limited.
One recent human study investigated the effects of caffeine, THC and CBD when administered together. The findings suggested that adding CBD to THC and caffeine was associated with stronger perceived effects and poorer performance on some tasks compared with THC alone.
Effects of Caffeine and CBD on THC
In September 2025, researchers published a randomised, placebo-controlled study [1] investigating what happens when caffeine, THC and cannabidiol (CBD) are taken together.
The study was the first to directly examine how these commonly used compounds may influence one another in humans. The findings highlight the importance of considering the wider cannabinoid profile of a product, rather than focusing on THC content alone, when thinking about its potential effects.
How was the Study Conducted?
Researchers recruited 20 healthy adults who were infrequent cannabis users. Each participant attended four separate study sessions and received a different combination of substances during each visit.
The four study conditions were:
- Placebo
- THC only (7.5 mg)
- THC and Caffeine (7.5 mg THC and 180 mg caffeine)
- THC, Caffeine, and CBD (7.5 mg THC, 180 of caffeine, and 105 mg CBD)
The doses of THC, CBD and caffeine were selected to reflect amounts that may be found in some commercially available products.
Throughout the study, researchers assessed three key areas:
- Subjective Effects including perceived intoxication, pleasant effects and anxiety.
- Performance, including reaction time, psychomotor performance, hand-eye coordination and simulated driving ability.
- Pharmacokinetics, which assessed how the body processed each substance by measuring cannabinoid and caffeine concentrations in blood samples.
The Effect of Caffeine on THC
One of the study’s key findings was that caffeine had little effect on THC at the doses tested.
When caffeine was combined with THC, researchers found no meaningful changes in participants’ perceived effects, performance, or the way THC was processed by the body.
Although there were some signals of increased perceived driving impairment, caffeine did not appear to substantially increase or reduce the effects of THC overall. These findings suggest that caffeine is unlikely to dramatically alter the THC experience, but they also provide little evidence that caffeine can offset unwanted effects associated with THC.
The Effect of CBD on THC
The study’s most notable finding was the effect of CBD on THC. Although CBD is sometimes thought to moderate the effects of THC, participants in this study reported stronger effects when CBD was combined with THC and caffeine than when THC was taken alone.
Researchers observed several important differences:
- Stronger Perceived Effects: Participants reported greater feelings of euphoria and stronger overall subjective effects when CBD was added to THC and caffeine.
- Reduced Performance: The combination was associated with poorer performance on psychomotor tasks. Participants also reported a greater reduction in their confidence and willingness to drive compared with THC alone.
- Changes in how THC was processed: CBD increased the concentration of THC and its active metabolite in participants’ blood. This suggests that CBD altered the way THC was processed by the body, potentially increasing its effects. The researchers noted that this interaction was observed with oral dosing and may not occur with other administration methods, such as vaporisation.
This robust drug-drug interaction is specific to oral dosing and may not occur with other methods like vaporisation.
The Simultaneous Effects of Cannabidiol (CBD) and Caffeine
While the previous study examined the effects of caffeine, THC and CBD together, researchers have also investigated whether caffeine affects CBD on its own.
In August 2024, researchers published the first human study to directly examine how caffeine and CBD may interact in healthy adults.[2]
How Was the Study Conducted?
Researchers recruited 54 healthy adults who consumed an average of 426.2 mg of caffeine per day.
The investigation consisted of two separate studies. One examined higher doses of CBD, while the other focused on lower doses that are more commonly found in over-the-counter products.
Participants in the higher-dose study received one of the following combinations:
- 200 mg caffeine + 0 mg CBD
- 200 mg caffeine + 80 mg CBD
- 200 mg caffeine + 160 mg CBD
- 200 mg caffeine + 240 mg CBD
Participants in the lower-dose study received:
- 200 mg caffeine + 0 mg CBD
- 200 mg caffeine + 25 mg CBD
- 200 mg caffeine + 50 mg CBD
Interactions Between Caffeine and CBD
The findings suggested that caffeine and CBD do not appear to interact in a meaningful way at the doses examined in this study.
The researchers found that lower doses of CBD, similar to those commonly found in over-the-counter products, did not alter the effects of caffeine or increase negative effects such as irritability or anxiety.
Some participants did report positive effects, including greater liking of the drug effects and reduced pain.
Importantly, the researchers did not identify any significant adverse interactions between caffeine and CBD in the study population. While further research is needed, these findings suggest that consuming caffeine and CBD together is unlikely to have a major impact on how either substance is experienced.
Key Takeaways
Research into the interaction between THC, CBD and caffeine is still emerging, but these studies provide some of the first human evidence on how these compounds may affect one another.
The findings suggest that caffeine has little effect on THC at the doses studied and does not appear to meaningfully alter the effects of CBD. However, the interaction between CBD and THC was more significant. Participants reported stronger effects when CBD was combined with THC and caffeine, and researchers observed higher concentrations of THC in the bloodstream.
These findings highlight the importance of considering the wider cannabinoid profile of a product, rather than focusing on THC content alone. For some people, adding CBD to an oral THC product may result in stronger effects than expected.
As research in this area continues to develop, a better understanding of how cannabinoids and other compounds interact may help patients make more informed decisions about their treatment.
If you’d like to learn more about THC and its effects, explore our guide to THC.
Disclaimer: This blog post is for informational purposes only and is based on a specific clinical study. It is not medical advice. The efficacy and safety of medical cannabis have not been established. Patients should always consult a qualified healthcare professional before making any decisions about their treatment.
References
[1] Strickland, J.C., Tilton, H.E., Patton, N.M. et al. Effect of caffeine and cannabidiol (CBD) co-administration on Δ9-tetrahydrocannabinol (Δ9-THC) subjective effects, performance impairment, and pharmacokinetics. Neuropsychopharmacol. 50, 1827–1835 (2025). https://doi.org/10.1038/s41386-025-02232-x
[2] Ferretti, M. L., Gustin, N. D., Sokol, C. M., Zamarripa, C. A., Feldner, M. T., Bonn-Miller, M. O., & Irons, J. G. (2024). A preliminary investigation of the simultaneous effects of cannabidiol and caffeine.Experimental and Clinical Psychopharmacology, 32(4), 475–484. https://doi.org/10.1037/pha0000691
