Using a fluoride mouthwash straight after brushing is fairly pointless: you’re flushing away fluoride and replacing it with more of the same. Where it can come in handy, however, is in topping up fluoride levels in between toothbrushing – particularly if you’re at high risk of cavities. “It can also be useful if you have had something acidic to eat, so don’t want to brush,” says Therese Hosey.
Mouthwashes contain more than just fluoride; many contain antiseptic agents such as chlorhexidine, which kill some of the bacteria your toothbrush misses, and help freshen the breath. But while there is some evidence that such mouthwashes can reduce plaque and gum inflammation, the Centre for Evidence-based Dentistry
ays: “If you’re brushing your teeth twice or three times a day with a fluoride toothpaste, the additional benefit you will get isn’t likely to be huge.”