Kava and Coffee: Is It Safe to Mix Them?

For most healthy adults, kava and coffee are not known to clash, but no trial has tested their safety together. In 12 adults, 28 days of kava did not significantly change the enzyme that tests caffeine breakdown¹, though one letter reports the opposite². The main risks are separate: kava's rare liver injury and caffeine's effect on anxiety and sleep.

This guide covers the combination only. For dosing, forms and the full evidence on kava, see its own page, and for the research on kava for anxiety, see the pair page.

Nothing in the research we found rules it out, but no study has tested the safety or effects of kava and coffee taken together. The only human data are a caffeine-clearance study in 12 adults¹, covered below. The safety picture comes from what each one does alone.

The two do not share an active ingredient. Kava root works through kavalactones such as kawain and methysticin³, which act on GABA activity, monoamine oxidase B and noradrenaline and dopamine re-uptake⁴. Caffeine works by blocking adenosine receptors⁵.

Does kava have caffeine?

Kava's psychoactive compounds are kavalactones³, and none of the kava studies we read measured caffeine in the root. Any caffeine in a kava-and-coffee drink should come from the coffee, which the FDA lists with tea and chocolate as a main source⁶. Kava drinks are sold at kava bars at many locations in the United States⁷. We found no analysis of kava-coffee products, and restaurants are not required by law to state caffeine content⁶, so ask what is in the cup.

The evidence is thin and partly conflicting. Researchers measure the activity of a liver enzyme called CYP1A2 by how fast caffeine breaks down into paraxanthine¹. Three lines of evidence bear on whether kava slows that step:

• Best human data, no effect on CYP1A2: In a randomized crossover study, 12 healthy adults took a kava extract for 28 days. Caffeine-based CYP1A2 measures did not change significantly, while CYP2E1 activity fell by about 40%¹.
• Test-tube data, possible effect: Whole kava extract at 100 µM total kavalactones inhibited CYP1A2 by 56% in human liver microsomes, while CYP2E1 was unaffected³. This is the opposite pattern to the human study.
• Traditional water extracts, size unknown: A 2005 letter titled "Traditional aqueous kava extracts inhibit cytochrome P450 1A2 in humans" reports an effect in people who drink water-based kava². The record has no abstract, so we cannot say how large the effect was.

A 2004 review concluded that true kava drug interactions remain unsubstantiated, with few combinations actually tested⁸. If heavy traditional kava drinking did slow caffeine clearance, a coffee would last longer, which matters most for sleep. That is a reasoned guess, not a measured result.

No trial has measured this. Each substance has a clear profile on its own, and they pull in different directions on alertness.

• Kava and anxiety: A Cochrane review of 11 trials with 645 participants found kava extract lowered Hamilton Anxiety scores by 5.0 points more than placebo across 6 studies (95% CI 1.1 to 8.8)⁹. A 6-week trial in 58 analysed adults with generalised anxiety disorder found a moderate benefit (Cohen's d = 0.62)¹⁰. A 16-week trial in 171 adults found no benefit, with a 1.37-point difference favouring placebo (p = 0.25)¹¹. The NCCIH says kava may help anxiety but does not appear helpful for generalised anxiety disorder⁷.
• Kava and thinking: A review of 10 human trials found no replicated significant negative effects of kava on cognition¹².
• Caffeine and alertness: Doses from about 40 mg to about 300 mg improve alertness, vigilance, attention and reaction time⁵.

The clash is on anxiety. A meta-analysis of 14 studies in 546 healthy participants found caffeine raised anxiety (standardized mean difference 0.94), by 0.61 at low doses and 2.86 at doses above 400 mg¹³. Someone who takes kava to calm down could plausibly undo some of that with a large coffee, though no trial has checked.

Kava is the liver concern here, not coffee. The NCCIH reports rare cases of kava-linked liver injury, some serious or fatal⁷. It also lists digestive upset, headache and dizziness as side effects, and long-term high doses may cause scaly skin (kava dermopathy)⁷. A clinical review assessed 14 patients with liver disease after kava: causality was highly probable in 1, probable in 4 and possible in 9. Risk factors were overdose, prolonged treatment and comedication¹⁴.

The trials give a mixed picture:

• 6-week trial, 75 adults: no significant differences in liver function tests between kava and placebo¹⁵.
• 16-week trial, 171 adults: liver function test abnormalities were significantly more frequent with kava, although no participant met the criteria for herb-induced liver injury¹¹.

Coffee looks liver-friendly in observational data. A systematic review linked coffee to better GGT, AST and ALT values in people at risk of liver disease, and to lower mortality in cirrhosis¹⁶. A meta-analysis of prospective studies found regular coffee drinkers had a relative risk of 0.62 for chronic liver disease¹⁷. These studies cannot show cause, and none tested whether coffee protects against kava-related injury. Do not treat coffee as a safeguard.

For kava and acetaminophen specifically, see our guide to Tylenol and supplements.

Caffeine is the one to time carefully. In a home trial, 400 mg of caffeine taken at bedtime, 3 hours before or 6 hours before significantly disturbed sleep compared with placebo¹⁸. A meta-analysis of 24 studies found caffeine cut total sleep time by 45 minutes and sleep efficiency by 7%, and added 9 minutes to the time taken to fall asleep¹⁹.

The same meta-analysis advised drinking coffee (107 mg per 250 mL) at least 8.8 hours before bed¹⁹. If you take kava in the evening to unwind, keep the coffee in the morning. For other options, see our guide to sleep supplements.

Some groups should change the plan or check with a clinician first:

• People with panic disorder or high anxiety: In a meta-analysis of 237 patients, 51.1% had a panic attack after 400 to 750 mg of caffeine, and none did after placebo. Patients were far more vulnerable than healthy controls (53.9% versus 1.7%)²⁰. A 2025 crossover trial found 150 mg did not raise subjective anxiety in 29 patients and 53 controls, but it did increase arousal and avoidance behaviour²¹. See panic disorder and anxiety.
• People with liver disease or on liver-affecting medicines: Regular kava users are advised to have routine liver function tests⁴. In vitro, whole kava extract inhibited CYP2C9 by 92%, CYP2C19 by 86%, CYP3A4 by 78% and CYP2D6 by 73%³. Ask a pharmacist about your medicines.
• Anyone drinking alcohol: The NCCIH says kava should not be used with alcohol or other sedatives⁷. In a human study, kava plus alcohol produced larger impairment on a divided-attention test than alcohol alone²².
• Drivers: In a simulator study of 22 adults, 180 mg of kavalactones did not impair driving, while 30 mg of oxazepam did²³. Larger recreational doses were not tested, and a review advises avoiding high kava doses before driving⁴. No evidence shows caffeine offsets kava's sedation.
• Pregnancy and breastfeeding: The NCCIH notes special risks from kava's harmful pyrone compounds⁷. The FDA advises talking to a provider about limiting caffeine if you are pregnant, trying to become pregnant or breastfeeding⁶.
• Children and teens: The FDA says caffeinated drinks should be avoided under age 2, and medical experts advise against energy drinks for children and teens⁶.

Treat these as sensible limits drawn from the studies above, not a tested protocol:

1. Cap caffeine at 400 mg a day (adults). The FDA cites 400 mg, about 2 to 3 cups of 12 fluid ounces, as an amount not generally linked to negative effects for most adults⁶. Aim lower if caffeine makes you anxious or if you are pregnant or breastfeeding.
2. Finish coffee about 9 hours before bed. The meta-analysis put the cut-off at 8.8 hours for a 250 mL cup¹⁹.
3. Keep alcohol out. Kava plus alcohol worsened impairment²².
4. Count every caffeine source. Decaf coffee still has 2 to 15 mg per 8 fluid ounces⁶.
5. Have liver tests if you take kava regularly, and tell your clinician about it⁴.

Related caffeine pairing: creatine and coffee.

We searched the medical literature for studies combining kava and caffeine, then for kava's liver and cytochrome P450 effects, kava and caffeine trials in anxiety, caffeine and sleep, and coffee and liver health. We prioritised systematic reviews, randomized trials and guidance from the FDA and the NCCIH, and cited 21 journal papers and 2 agency pages. No study we found tested the safety of kava and caffeine together, so the combination verdict is inferred. Checked 2 November 2026.

1. Gurley BJ, et al. In vivo effects of goldenseal, kava kava, black cohosh, and valerian on human cytochrome P450 1A2, 2D6, 2E1, and 3A4/5 phenotypes. Clin Pharmacol Ther. 2005;77(5):415-26. doi:10.1016/j.clpt.2005.01.009 Our study summary.
2. Russmann S, et al. Traditional aqueous kava extracts inhibit cytochrome P450 1A2 in humans: Protective effect against environmental carcinogens?. Clin Pharmacol Ther. 2005;77(5):453-4. doi:10.1016/j.clpt.2005.01.021
3. Mathews JM, et al. Inhibition of human cytochrome P450 activities by kava extract and kavalactones. Drug Metab Dispos. 2002;30(11):1153-7. doi:10.1124/dmd.30.11.1153
4. Sarris J, et al. Kava: a comprehensive review of efficacy, safety, and psychopharmacology. Aust N Z J Psychiatry. 2011;45(1):27-35. doi:10.3109/00048674.2010.522554
5. McLellan TM, et al. A review of caffeine's effects on cognitive, physical and occupational performance. Neurosci Biobehav Rev. 2016;71:294-312. doi:10.1016/j.neubiorev.2016.09.001
6. U.S. Food and Drug Administration. Spilling the Beans: How Much Caffeine is Too Much? Consumer Update, 2024. https://www.fda.gov/consumers/consumer-updates/spilling-beans-how-much-caffeine-too-much
7. National Center for Complementary and Integrative Health. Kava: Usefulness and Safety. Updated April 2025. https://www.nccih.nih.gov/health/kava
8. Anke J, et al. Pharmacokinetic and pharmacodynamic drug interactions with Kava (Piper methysticum Forst. f.). J Ethnopharmacol. 2004;93(2-3):153-60. doi:10.1016/j.jep.2004.04.009
9. Pittler MH, et al. Kava extract for treating anxiety. Cochrane Database Syst Rev. 2003;2003(1):CD003383. doi:10.1002/14651858.CD003383 Our study summary.
10. Sarris J, et al. Kava in the treatment of generalized anxiety disorder: a double-blind, randomized, placebo-controlled study. J Clin Psychopharmacol. 2013;33(5):643-8. doi:10.1097/JCP.0b013e318291be67 Our study summary.
11. Sarris J, et al. Kava for generalised anxiety disorder: A 16-week double-blind, randomised, placebo-controlled study. Aust N Z J Psychiatry. 2020;54(3):288-297. doi:10.1177/0004867419891246 Our study summary.
12. LaPorte E, et al. Neurocognitive effects of kava (Piper methysticum): a systematic review. Hum Psychopharmacol. 2011;26(2):102-11. doi:10.1002/hup.1180
13. Liu C, et al. Caffeine intake and anxiety: a meta-analysis. Front Psychol. 2024;15:1270246. doi:10.3389/fpsyg.2024.1270246
14. Teschke R. Kava hepatotoxicity--a clinical review. Ann Hepatol. 2010;9(3):251-65. https://pubmed.ncbi.nlm.nih.gov/20720265/
15. Sarris J, et al. Kava for the treatment of generalized anxiety disorder RCT: analysis of adverse reactions, liver function, addiction, and sexual effects. Phytother Res. 2013;27(11):1723-8. doi:10.1002/ptr.4916
16. Saab S, et al. Impact of coffee on liver diseases: a systematic review. Liver Int. 2014;34(4):495-504. doi:10.1111/liv.12304
17. Bravi F, et al. Coffee and the risk of hepatocellular carcinoma and chronic liver disease: a systematic review and meta-analysis of prospective studies. Eur J Cancer Prev. 2017;26(5):368-377. doi:10.1097/CEJ.0000000000000252
18. Drake C, et al. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013;9(11):1195-200. doi:10.5664/jcsm.3170 Our study summary.
19. Gardiner C, et al. The effect of caffeine on subsequent sleep: A systematic review and meta-analysis. Sleep Med Rev. 2023;69:101764. doi:10.1016/j.smrv.2023.101764
20. Klevebrant L, et al. Effects of caffeine on anxiety and panic attacks in patients with panic disorder: A systematic review and meta-analysis. Gen Hosp Psychiatry. 2022;74:22-31. doi:10.1016/j.genhosppsych.2021.11.005
21. Hoppe JM, et al. Acute effects of 150 mg caffeine on subjective, physiological, and behavioral components of anxiety in panic disorder and healthy controls - A randomized placebo-controlled crossover trial. J Psychopharmacol. 2025;39(8):836-846. doi:10.1177/02698811251344692
22. Foo H, et al. Acute effects of kava, alone or in combination with alcohol, on subjective measures of impairment and intoxication and on cognitive performance. Drug Alcohol Rev. 1997;16(2):147-55. doi:10.1080/09595239700186441
23. Sarris J, et al. Does a medicinal dose of kava impair driving? A randomized, placebo-controlled, double-blind study. Traffic Inj Prev. 2013;14(1):13-7. doi:10.1080/15389588.2012.682233