Should I Floss Before or After Brushing?

You have the brush in one hand and the floss on the counter. Which comes first? Dental guidance gives two different answers to that small question, and the research measures something narrower than whether your breath will smell better tomorrow.

What the guidance says

The NHS¹ recommends flossing before brushing. Its adult routine also calls for fluoride toothpaste and about two minutes of brushing twice a day, including before bed. After brushing, spit out excess toothpaste without immediately rinsing with water. The reason given is that rinsing washes away the concentrated fluoride left by the toothpaste.¹

The American Dental Association’s² patient page says timing does not matter as long as flossing is thorough. It recommends making flossing a daily habit and choosing a time when you can give the task attention. Morning or after lunch are options if you are too tired at night.²

Those are UK and US patient recommendations, respectively. Both include daily cleaning between teeth; they differ on how strongly to prescribe the order.¹²

What a 2026 trial actually measured

Researchers randomly assigned 56 college students to floss then brush, or brush then floss. Participants received instruction in brushing and flossing. Researchers assessed plaque with an index that scores tooth surfaces, including areas between teeth.³

Flossing first produced greater plaque-score reductions at the upper and lower front teeth, including the surfaces between them. The abstract reports no statistically significant difference between groups in the other regions. That is a more specific finding than saying flossing first cleaned every tooth better.³

The reported outcome was plaque removal. It was not a measurement of breath odor, new cavities over years, or whether people would maintain the sequence at home. A trial in college students also cannot establish the same result for every age group or dental condition. We reviewed the published abstract for this study, rather than an accessible full report.³

Choose an order you can complete

If you are setting up a routine, put the floss beside the brush and use it first. Then brush all tooth surfaces. Following the UK routine, spit out the excess toothpaste and keep mouthwash for another time, such as after lunch.¹

If cleaning between teeth after lunch is the habit you maintain, the US guidance supports that timing. Our daily flossing article covers frequency and technique in more detail.²

Order cannot compensate for missing a tooth surface. Guide floss gently, curve it against the tooth and clean its side rather than snapping the strand into the gum. Persistent pain while cleaning between teeth is a reason to ask your dentist to assess the technique and your mouth.²

The play

Try this: ask for a technique check

At your next dental visit, describe the order you use and ask to demonstrate the places you find difficult. That makes the conversation about how you clean those teeth, rather than about whether your routine matches a video.

Connect the routine to the source of breath concerns

Is It My Breath? includes a two-minute routine in Chapter 6, with daily cleaning between teeth, fluoride toothpaste and separate timing for mouthwash. Its Source Map helps organize possible contributors to breath concerns. The book’s routine offers a place to start; changing flossing order does not identify the cause of persistent breath odor. See the book.