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Does CBD help with nausea? A THC-CBD extract helps chemo nausea; CBD alone is less clear

A THC-CBD extract eased hard-to-treat chemotherapy nausea in two trials, but it contains THC and can cause sedation. Evidence for CBD alone is thin.

Published October 2026

Short answer

The strongest results are for a THC:CBD extract in hard-to-treat chemotherapy nausea. For CBD alone, evidence is limited: one small gastroparesis trial found relief while slowing stomach emptying; a dyspepsia trial found none. Evidence grade C (Limited). One 44-person single-centre CBD trial found symptom relief (with slowed stomach emptying) and a small dyspepsia trial found none, while two trials of a THC:CBD extract in refractory chemotherapy nausea were positive; downgraded for small samples, inconsistency and indirectness (THC:CBD is not CBD alone; pooled cannabinoid trials used older drugs and regimens).

Key takeaways

  • In a 44-person trial in people with gastroparesis, a prescription CBD medicine given for four weeks reduced vomiting episodes and other stomach symptoms versus placebo, but it also slowed stomach emptying [1].
  • In a separate four-week trial in people with functional dyspepsia (indigestion) and normal stomach emptying, CBD did not improve digestive symptoms or stomach function [2].
  • For chemotherapy nausea that standard medicines had not controlled, a THC:CBD capsule raised the proportion with no vomiting and no rescue medicine from 8% to 24% in a 147-person trial, and from 14% to 25% in a smaller crossover trial [3][4].
  • Older trials of cannabis-based medicines, mostly the THC drugs nabilone and dronabinol, beat placebo for chemotherapy nausea but were no better than the older anti-sickness drug prochlorperazine, and caused more side effects [5].
  • Heavy, long-term cannabis use can cause cannabinoid hyperemesis syndrome — repeated bouts of severe vomiting that stop when cannabis is stopped [6].

The short version

CBD on its own has only limited evidence for easing nausea [1][2]. In the strongest trial of CBD alone — a 44-person study in gastroparesis, a condition where the stomach empties slowly — a prescription CBD medicine reduced vomiting episodes and other stomach symptoms, but it also slowed the stomach's emptying [1], and a separate trial in functional dyspepsia found no benefit [2]. The clearer signal comes from a THC:CBD extract, which improved chemotherapy nausea and vomiting that standard anti-sickness medicines had not controlled, at the cost of more sedation and dizziness [3][4].

What the studies show

CBD alone. In a 44-person trial, adults with idiopathic or diabetic gastroparesis took a prescription CBD medicine or a placebo for four weeks [1]. The dose was escalated toward 20 mg/kg a day [1]. CBD lowered the total symptom score and the number of vomiting episodes per day, and people tolerated more of a liquid meal [1]. The catch: stomach emptying slowed — the time for 10% of a solid meal to leave the stomach rose from about 77 to 101 minutes, and less of the meal had emptied at 2 and 4 hours [1]. Diarrhoea was more common with CBD (12 of 21 people, versus 2 of 23 on placebo) [1].

The other trial of CBD alone for digestive symptoms found nothing: in people with functional dyspepsia (indigestion) and normal stomach emptying, four weeks of CBD did not change symptoms or stomach function [2]. A 2025 guideline from the American Gastroenterological Association conditionally recommends against CBD as a first-line treatment for gastroparesis [7].

THC plus CBD for chemotherapy nausea. In a phase II/III trial, 147 adults with nausea or vomiting during chemotherapy, despite guideline-standard anti-sickness medicines, took capsules of THC 2.5 mg plus CBD 2.5 mg — or placebo — three times a day around each chemotherapy cycle [3]. A complete response (no vomiting and no rescue medicine in the five days after chemotherapy) rose from 8% with placebo to 24% with THC:CBD [3]. More people had bothersome sedation (18% versus 7%), dizziness (10% versus 0%) and short-lived anxiety (4% versus 1%) [3]. An earlier phase II crossover trial found a similar jump, from 14% to 25%, with 31% reporting moderate or severe side effects such as sedation or disorientation; 83% preferred the cannabis capsules to placebo [4].

Older evidence on other cannabinoids. A Cochrane review of 23 randomised trials, almost all run between 1975 and 1991, found cannabis-based medicines — mostly the THC-based drugs nabilone and dronabinol — reduced chemotherapy nausea and vomiting compared with placebo, but worked no better than the older anti-sickness drug prochlorperazine and caused more sedation, dizziness and feeling high [5]. A 2025 meta-analysis of 26 trials agreed: cannabinoids beat placebo but not other anti-sickness drugs, and 23 of the 26 trials were published before 2000 [8]. The 2024 ASCO guideline says cannabis or cannabinoids may improve refractory chemotherapy-induced nausea and vomiting when added to standard antiemetics, but rates the certainty of the evidence as low [9].

Real-world reports. An app-based study recorded 2,220 cannabis self-treatments for nausea by 886 people; 96% reported relief within an hour, and products with more THC and less CBD were linked to greater relief [10]. With no placebo group, expectation and other biases can't be ruled out [10].

The nuances

The evidence is small and narrow. The positive CBD-alone trial had 44 people, one centre, and it has not been repeated [1]. The THC:CBD trials were only in people having chemotherapy [3][4], and the pooled cannabinoid evidence is dominated by trials run before 1991, when chemotherapy and anti-sickness drugs were different [5][8].

"CBD" in these trials means regulated medicines — a prescription CBD liquid or 2.5 mg THC:CBD capsules — not the over-the-counter oils most people buy, and many over-the-counter cannabinoid products are unregulated [1][3][11].

The THC:CBD extract contains THC, so it can cause drowsiness, dizziness and anxiety [3][4], and experts advise avoiding cannabis in pregnancy, while driving, and in people prone to mental health problems [12].

Heavy, long-term cannabis use can also cause cannabinoid hyperemesis syndrome: repeated bouts of severe vomiting with abdominal pain that often ease with hot showers and stop when cannabis is stopped [6]. In US emergency departments, visits linked to it rose from about 4 per 100,000 in 2016 to about 22 per 100,000 in 2022 [13].

If you take prescription medicines, interactions matter: CBD is processed by the same liver enzymes as many drugs, and case reports link cannabinoids to changed blood levels of warfarin, valproate, tacrolimus and sirolimus, with problems including bleeding and sedation [11].

Health organisations advise avoiding cannabis and CBD during pregnancy and breastfeeding, because data on CBD alone in pregnancy are very limited [14].

What this means for you

If chemotherapy nausea is not controlled by standard anti-sickness medicines, the strongest evidence is for a THC:CBD extract added to those medicines, taken under medical supervision [3][9]. For nausea from other causes, the trials we found tested CBD only in gastroparesis and functional dyspepsia [1][2]. Over-the-counter CBD oils are not the pharmacy-made medicines used in these trials [11], and a doctor or pharmacist can advise what fits your situation and your other medicines [11].

Go deeper

  • CBD — Small trials suggest CBD can take the edge off anxiety, but a 54-trial review found no clear benefit.

References

  1. A Randomized, Controlled Trial of Efficacy and Safety of Cannabidiol in Idiopathic and Diabetic Gastroparesis.. Clin Gastroenterol Hepatol, 2023.
  2. Cannabidiol for Functional Dyspepsia With Normal Gastric Emptying: A Randomized Controlled Trial.. Am J Gastroenterol, 2022.
  3. Oral Cannabis Extract for Secondary Prevention of Chemotherapy-Induced Nausea and Vomiting: Final Results of a Randomized, Placebo-Controlled, Phase II/III Trial.. J Clin Oncol, 2024.
  4. Oral THC:CBD cannabis extract for refractory chemotherapy-induced nausea and vomiting: a randomised, placebo-controlled, phase II crossover trial.. Ann Oncol, 2020.
  5. Cannabinoids for nausea and vomiting in adults with cancer receiving chemotherapy.. Cochrane Database Syst Rev, 2015.
  6. Cannabinoid Hyperemesis Syndrome: Diagnosis, Pathophysiology, and Treatment-a Systematic Review.. J Med Toxicol, 2017.
  7. AGA Clinical Practice Guideline on Management of Gastroparesis.. Gastroenterology, 2025.
  8. Efficacy of cannabinoids for the prophylaxis of chemotherapy-induced nausea and vomiting-a systematic review and meta-analysis.. Support Care Cancer, 2025.
  9. Cannabis and Cannabinoids in Adults With Cancer: ASCO Guideline.. J Clin Oncol, 2024.
  10. The Effectiveness of Common Cannabis Products for Treatment of Nausea.. J Clin Gastroenterol, 2022.
  11. Systematic review of drug-drug interactions of delta-9-tetrahydrocannabinol, cannabidiol, and Cannabis.. Front Pharmacol, 2024.
  12. Balancing risks and benefits of cannabis use: umbrella review of meta-analyses of randomised controlled trials and observational studies.. BMJ, 2023.
  13. Cannabinoid Hyperemesis Syndrome, 2016 to 2022.. JAMA Netw Open, 2025.
  14. Medical Cannabis During Pregnancy and Breastfeeding: Is the Concern Fully Evidence-Based?. Biomedicines, 2026.