Does coffee cause bloating?

No trial has measured bloating after coffee, and the largest population study points the other way. Among 16,840 Swedish adults aged 45 to 75, those who drank more coffee reported less functional bloating, with a p for trend of .007, while those who drank more tea reported more. That is self-reported and observational, and people whose stomachs react may simply drink less coffee. What trials do show is that coffee moves the bowel. In 12 healthy adults a cup of caffeinated coffee stirred the colon as strongly as a 1000 calories meal.

Unsettled. The randomized evidence is about the gut speeding up, and that is not the same thing as bloating. A minority of people do get symptoms from coffee. In 30 adults who already knew coffee bothered them, both test coffees caused heartburn, regurgitation and dyspepsia in most of them, and that trial did not report bloating separately.

What the trials found

The physiology is the clearest part. In a randomized study of 12 healthy adults, 8.1 fl oz (240 ml) of black coffee with 150 mg of caffeine drove colonic contractions about as hard as a 1000 calories meal, 60 percent more than water and 23 percent more than decaffeinated coffee. Bloating was not measured, and twelve people is a small sample.

After surgery the same effect becomes useful. In 96 women recovering from laparoscopic gynecological surgery, 3 cups of coffee a day brought the first passing of gas to a median of 19 hours against 25 hours with warm water, a hazard ratio of 1.9 with an interval of 1.2 to 2.9. Ileus fell from 14.9 percent to 2.0 percent and no adverse events were put down to coffee. The trial was open label. A 2025 umbrella review of 24 meta-analyses listed coffee among 8 treatments that significantly improve gut recovery after surgery, at Class II, without a pooled number for coffee in its abstract.

The trial that looked for harm chose people likely to show it. Thirty adults who reported coffee sensitivity took two coffees roasted in different ways, double-blind, fasting and after a standard meal. Most of them had heartburn, regurgitation and dyspepsia with both, and the roasting made no difference to how often or how badly. A different roast did not help those people.

Population studies of irritable bowel syndrome disagree with each other. A 2023 meta-analysis of 8 observational studies in 432,022 people found coffee drinkers had 17 percent lower odds of IBS than abstainers, an odds ratio of 0.83 with an interval of 0.79 to 0.87. The studies were poor quality, heterogeneity was high and a single large cohort drove the result. The paper gives no absolute risk. In 3,362 Iranian adults, drinking coffee weekly or more went with 44 percent higher odds of IBS, 1.44 with an interval of 1.02 to 2.04, and within men and within women separately the link was not clear. The same Iranian adults showed no significant link between coffee and functional dyspepsia. A review of 16 studies on food and functional dyspepsia found caffeine linked with symptoms in 4 of them, alongside dietary fat and wheat, without pooling them.

Who should be careful

Not for everyone. If coffee already gives you heartburn or an uncomfortable stomach, the 30-person trial says you are probably right about it and a different roast is unlikely to change that. The US Food and Drug Administration says people who are pregnant, trying to conceive or breastfeeding, or who take some medicines, should ask a clinician whether to limit caffeine.

For most healthy adults the FDA cites 400 mg of caffeine a day, about two to three 12-fluid-ounce cups of coffee, as an amount not generally associated with negative effects. That figure is about caffeine in general and says nothing about bloating, and sensitivity varies from person to person.

What expert bodies say

NICE, which writes clinical guidance for England and Wales, advises adults with irritable bowel syndrome to restrict tea and coffee to 3 cups a day and to drink mainly water or other caffeine-free drinks. It is general dietary advice for IBS and is not drawn from a trial of coffee and bloating. We found no expert body that names coffee as a cause of bloating in people without IBS.

How we searched

What would change this answer

• A randomized trial with bloating as the primary outcome, comparing caffeinated coffee, decaf and water in people who report bloating. We found no such trial, and none comparing decaf with regular coffee for bloating.
• A cohort study that follows people over time and records bloating separately from IBS, which would show whether the Swedish finding survives once people who avoid coffee because of symptoms are accounted for.
• A better pooled estimate for IBS that does not hang on one large cohort.

More on coffee, including what the evidence says beyond the gut: coffee →

Sources

1. ev-cfbl-01 · Meta-analysis or systematic review · umbrella review of meta-analyses · n = 24 meta-analyses
   Among them, chewing gum, coffee, ERAS(Enhanced Recovery After Surgery) protocols, acupuncture, opioid receptor antagonists, Da-Cheng-Qi-Tang, early enteral nutrition, and Zusanli point injection therapy have been shown to significantly improve postoperative ileus (Class II).
   
   Who: surgical patients in meta-analyses of treatments for postoperative ileus
   Effect: coffee improves postoperative ileus (Class II evidence); no pooled effect size for coffee in the abstract
   Certainty: indirect: postoperative ileus, not bloating in everyday life; Class II, no number for coffee in abstract
   Langenbecks Arch Surg, 2025 · checked 2026-10-07 · we read the abstract
2. ev-cfbl-02 · Randomized controlled trial(s) · randomized controlled trial · n = 96
   The median time to flatus (19 [13-35] vs. 25 [15-42] h; hazard ratio [HR] 1.9, 95% confidence interval [CI], 1.2-2.9; P = 0.0009), median time to defecation (30 [22-54] vs. 38 [26-65] h, HR 2.4, 95% CI, 1.5-3.8; P < 0.0001), and mean time to tolerate food (2 [2-5] vs. 3 [2-8] days, HR 1.5, 95% CI, 1.02-2.3; P = 0.002) were decreased significantly in patients who consumed coffee compared with the control subjects.
   
   Who: women after laparoscopic total hysterectomy and salpingectomy; 3 cups of coffee vs warm water at 6, 12 or 18 h
   Effect: time to flatus 19 vs 25 h, HR 1.9 (95% CI 1.2 to 2.9); ileus 2.0% vs 14.9%; no adverse events attributed to coffee
   Certainty: post-surgical setting; open label
   Int J Surg, 2020 · checked 2026-10-07 · we read the abstract
3. ev-cfbl-03 · Randomized controlled trial(s) · randomized crossover physiological study · n = 12
   Its magnitude is similar to a meal, 60% stronger than water and 23% stronger than decaffeinated coffee.
   
   Who: healthy adults; 8.1 fl oz (240 ml) black coffee (150 mg caffeine), decaffeinated coffee or water in random order, plus a 1000 calories meal
   Effect: colonic motor activity: coffee similar to meal, 60% stronger than water, 23% stronger than decaf
   Certainty: tiny, healthy volunteers, motility measured, bloating not measured
   Eur J Gastroenterol Hepatol, 1998 · checked 2026-10-07 · we read the abstract
4. ev-cfbl-04 · Randomized controlled trial(s) · randomized double-blind crossover trial · n = 30
   Consumption of both coffees resulted in heartburn, regurgitation, and dyspepsia in most individuals.
   
   Who: adults who report coffee sensitivity, tested fasting and after a standard meal
   Effect: symptoms in most participants with both coffees; no difference in frequency or severity between roasting processes
   Certainty: selected coffee-sensitive people; upper GI symptoms, bloating not reported separately
   Dig Dis Sci, 2003 · checked 2026-10-07 · we read the abstract
5. ev-cfbl-05 · Observational data · population-based questionnaire study · n = 16,840
   A high tea intake was associated with abdominal pain (p for trend =.003), bloating (p for trend = .039) and diarrhea (p for trend <.001), whereas coffee intake was associated with a decreased risk of abdominal pain (p for trend = .002) and bloating (p for trend = .007).
   
   Who: EpiHealth participants aged 45-75 years, Sweden, organic bowel disease excluded
   Effect: coffee: lower risk of bloating (p for trend = .007) and abdominal pain (p for trend = .002); tea: higher bloating (p for trend = .039)
   Certainty: self-reported, observational; people with symptoms may avoid coffee (reverse causation)
   Scand J Gastroenterol, 2017 · checked 2026-10-07 · we read the abstract
6. ev-cfbl-06 · Observational data · systematic review and meta-analysis of observational studies · n = 432,022
   The same was observed when comparing coffee drinkers and abstainers (pooled OR: 0.83, 95% CI: 0.79 to 0.87), although the protective effect seems to be driven by a single large cohort study [32].
   
   Who: adults in observational studies of coffee intake and IBS
   Effect: coffee drinkers vs abstainers pooled OR 0.83 (95% CI 0.79 to 0.87), I2 > 75%; driven by a single large cohort
   Certainty: observational, high heterogeneity, poor primary studies, fixed-effects model
   Nutrients, 2023, 15(22):4745 (Examining the Association between Coffee Intake and the Risk of Developing Irritable Bowel Syndrome) · checked 2026-10-07 · we read the fulltext
7. ev-cfbl-07 · Observational data · cross-sectional study · n = 3,362
   In the whole study population, those who consumed coffee weekly or more had higher odds of IBS compared to those who did not take coffee (OR: 1.44; 95% CI: 1.02-2.04).
   
   Who: Iranian adults, SEPAHAN study, Rome III IBS
   Effect: coffee weekly or more vs none OR 1.44 (95% CI 1.02 to 2.04); men OR 1.44 (0.75 to 2.76), women OR 1.45 (0.96 to 2.19); top vs bottom caffeine tertile OR 1.47 (1.14 to 1.87)
   Certainty: cross-sectional; conflicts with the pooled estimate; bloating not analyzed separately
   Frontiers in Nutrition, 2021 (Association of Coffee and Caffeine Intake With Irritable Bowel Syndrome in Adults) · checked 2026-10-07 · we read the fulltext
8. ev-cfbl-08 · Observational data · cross-sectional study · n = 3,362
   After controlling for potential confounders, no significant association was observed between coffee (OR: 1.27; 95% CI: 0.86-1.87), and caffeine (OR: 1.00; 95% CI: 0.99-1.02) consumption and odds of FD.
   
   Who: Iranian adults aged 18-55, Rome III functional dyspepsia
   Effect: coffee OR 1.27 (95% CI 0.86 to 1.87), caffeine OR 1.00 (0.99 to 1.02), not significant
   Certainty: cross-sectional; same cohort as ev-cfbl-07
   Sci Rep, 2024 · checked 2026-10-07 · we read the abstract
9. ev-cfbl-09 · Observational data · systematic review of mixed designs · n = 16 studies
   Caffeine was associated with FD in four studies, although any association with alcohol was uncertain.
   
   Who: adults with functional dyspepsia or its symptoms
   Effect: caffeine associated with FD in four studies; no pooled estimate
   Certainty: mostly observational and self-report studies; no meta-analysis
   J Hum Nutr Diet, 2018 · checked 2026-10-07 · we read the abstract
10. ev-cfbl-10 · Position of an expert body · national clinical guideline · n = —
    Restrict tea and coffee to 3 cups per day.
    
    Who: adults with irritable bowel syndrome, England and Wales
    Effect: limit tea and coffee to 3 cups/day; at least 8 cups of fluid, mainly non-caffeinated
    Certainty: general advice for IBS, not a bloating-specific trial result
    NICE, Irritable bowel syndrome in adults: diagnosis and management, CG61, recommendation 1.2.1.4 (2008, updated 2017) · checked 2026-10-07 · we read the section
11. ev-cfbl-11 · Position of an expert body · government consumer guidance · n = —
    For most adults, the FDA has cited 400 milligrams* a day — that's about two to three 12-fluid-ounce cups of coffee — as an amount not generally associated with negative effects.
    
    Who: most healthy adults, US
    Effect: 400 mg/day reference amount; sensitivity varies
    Certainty: general caffeine limit, not about bloating
    US Food and Drug Administration, Spilling the Beans: How Much Caffeine is Too Much? (consumer update) · checked 2026-10-07 · we read the section
12. ev-cfbl-12 · Position of an expert body · government consumer guidance · n = —
    If you are concerned about a condition or medication, or if you’re pregnant, trying to become pregnant, or breastfeeding, we recommend talking to your health care provider about whether you need to limit caffeine consumption.
    
    Who: pregnant, trying to conceive or breastfeeding people; people with certain conditions or medications
    Effect: discuss caffeine limits with a health care provider
    Certainty: no number given for pregnancy on this page
    US Food and Drug Administration, Spilling the Beans: How Much Caffeine is Too Much? (consumer update) · checked 2026-10-07 · we read the section