Coffee usually takes the blame for brown teeth, yet in laboratory staining tests black tea often leaves the darker and more stubborn film. On acidity, plain coffee and plain tea are both mild. And for decay, the sugar stirred into the cup matters far more than the drink underneath it. So the fair answer to which is worse depends on which kind of damage you mean.
Stain: black tea has the edge
Both drinks contain coloured plant compounds, including tannins, that are drawn to the thin protein layer coating the teeth. Over time that layer picks up pigment and the enamel looks yellower or browner. In a 2022 laboratory study in the European Journal of Dentistry (Sarembe and colleagues), human enamel samples were cycled through eleven drinks. Black tea and red wine caused the most staining, coffee also stained significantly, and the black tea stain was the hardest to brush off. Adding milk to either drink changed the stain layer and how firmly it stuck.
Two caveats apply. The samples were also exposed to a chlorhexidine mouthwash, which is known to make staining worse, and two of the authors worked for a consumer healthcare company. Real mouths, with saliva, brushing and different drinking habits, will not behave exactly like a lab model. Even so, the result fits what dentists see: heavy tea drinkers can build up stain as readily as coffee drinkers.
Green tea is paler than black tea and is often assumed to stain less, but it still contains plant pigments, and herbal blends are not automatically stain-free either. A ginger and lemon infusion stained noticeably in the same study. Our articles on black tea and green tea look at each in more detail.
Acid: neither is a major erosion risk on its own
Erosion is enamel being softened and worn by acid rather than by bacteria. A widely cited study in the British Journal of Nutrition (Lussi and colleagues, 2012) measured how sixty foods, drinks and medicines affected enamel hardness in the lab. Coffee, and plain unflavoured teas, did not significantly soften enamel, while soft drinks, juices, sports drinks and many flavoured products did. Fruit-flavoured teas, iced teas and drinks with added citrus are a different matter and can be more acidic.
Sugar: what goes in the cup decides the decay risk
Black coffee and unsweetened tea give plaque bacteria very little to feed on. Sugar, honey and flavoured syrups change that, because bacteria turn sugar into acid, and that acid is what starts a cavity. Sipping a sweetened drink slowly over an hour keeps the teeth bathed in sugar for longer than drinking the same cup quickly. Milk contains some natural sugar, but plain milk is not generally regarded as a significant cause of decay. If you want sweetness without the sugar, our article on xylitol explains why some sweeteners are kinder to teeth.
Tea has one small point in its favour: the tea plant takes up fluoride from soil, so brewed tea contains some fluoride. The amount varies widely and it is not a substitute for fluoride toothpaste.
The three drinks side by side
| Coffee | Black tea | Green tea | |
|---|---|---|---|
| Staining | Can stain noticeably | Often the most stubborn stain | Paler, still contains pigments |
| Erosion when taken plain | Low in lab testing | Low in lab testing | Low in lab testing |
| Natural fluoride | Negligible | Some, varies by leaf and brew | Some, varies by leaf and brew |
| Main decay risk | Added sugar and syrups | Added sugar or honey | Added sugar or honey |
Habits that cut the effect without giving anything up
Drinking your coffee or tea within a reasonable time, rather than nursing it all morning, shortens the contact time for both pigment and sugar. A mouthful of water afterwards helps clear what is left on the teeth. A straw can help with iced drinks. Brushing twice a day with fluoride toothpaste and cleaning between the teeth matters for stain too, because pigment clings more readily to plaque and tartar than to clean, smooth enamel. There is no need for a fixed wait before brushing: a 2024 scoping review in Caries Research (Fernández and colleagues) found that brushing with fluoride toothpaste soon after an acidic drink did not add measurable wear, and rinsing with water after an acidic drink is a reasonable habit.
When stain has already built up
Surface stain that brushing cannot shift can usually be removed with a professional clean and polish by a dentist or OHT. Stain that has darkened the tooth itself is a different problem, and whitening is the option to discuss at a check-up once the teeth and gums have been examined. Our coverage of stains from coffee, wine and tea goes into this further.
If your daily cup is leaving its mark, our general dentistry team can check whether the stain is on or in the tooth and clean what can be removed. You can book at our Melrose Park practice and see new patient offers on our current deals page.
