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Is it bad to drink coffee on an empty stomach?

By GyroscopeUpdated November 15, 20265 sources

Not for most people. Coffee does make your stomach release acid, which is where the worry comes from. But in a study of 8,013 Japanese adults who had their stomachs checked with a scope, coffee drinkers didn’t have more ulcers or reflux, and a review of 15 studies found no link between coffee and reflux disease. If coffee first thing gives you heartburn, have it with breakfast.

The idea makes sense on paper. Coffee is acidic, it gets your stomach going, and with nothing else in there it seems like it must be eating at you. People get told to wait, or to eat first.

What the studies found

In 2013 doctors in Japan looked at 8,013 healthy adults who’d had a checkup scope. Two thirds drank coffee. After accounting for the things that do cause ulcers, like the stomach bug H. pylori and smoking, coffee had no link to stomach ulcers, duodenal ulcers or reflux. The researchers also pooled earlier studies and still found no link to ulcers.

A 2014 review of 15 studies came to the same answer for reflux disease. The odds were 1.06, which is no real difference. In one subgroup, where reflux was diagnosed with a scope instead of by symptoms, coffee drinkers did have higher odds, so the question isn’t fully closed.

One thing that does change

Coffee before food can make your blood sugar rise more after you eat. In a 2020 study, 29 young adults slept badly on purpose, waking every hour, then had about 300 mg of caffeine as strong black coffee before a sugary drink. Their blood sugar peaked at about 161 mg/dL (8.96 mmol/L), against about 148 mg/dL (8.23) when they had the same broken night without coffee. The broken night by itself didn’t change it. That’s a short-term effect in healthy people, and the long-term studies show coffee drinkers get less type 2 diabetes. glucose.guide explains both sides.

What we’d do

If coffee on an empty stomach feels fine, there’s no evidence you need to change it. If it gives you heartburn or makes you jittery, have it with breakfast or after a few bites. Coffee with food is like taking stairs instead of jumping. You get to the same place with less of a jolt.

Your last cup matters more than your first. A coffee at 7am leaves only about 11 mg in you at 11pm. There’s also no evidence you need to wait 90 minutes after waking (that myth is here). And if your first coffee sends you to the bathroom, that’s normal too, and why does coffee make you poop? explains it.