Why do gums bleed when flossing? When to worry

If your gums bleed when flossing, you are not alone. It is one of the most common things people notice about their gums. In most cases, bleeding when you floss or brush is a sign of gingivitis: inflammation of the gums caused by plaque building up along the gum line. The good news is that gingivitis can usually be reversed with gentle, regular cleaning. This guide explains why gums bleed, how to floss without hurting them, and when to worry about bleeding gums and see a dentist.

Is it normal for gums to bleed when flossing?

Healthy gums do not usually bleed with gentle brushing and flossing. Bleeding usually means the gum is inflamed, although snapping the floss can also injure the gum. It is common when you start flossing after a break, because the gum between the teeth has already been irritated by plaque. With gentle daily cleaning, this kind of bleeding usually settles within about 3 days. If it carries on for longer than 3 days, see your dentist, because the cause may be gum disease. Read more on our bleeding gums page.

Why do gums bleed when flossing? Common causes

Gingivitis (plaque at the gum line)

Plaque is a soft, sticky film of bacteria that forms on teeth every day. If it is not removed, the gums react with inflammation: they become red, swollen and bleed easily. Bleeding is one of the main signs that dentists use to identify gingivitis (Chapple and colleagues, 2018; Trombelli and colleagues, 2018). Gingivitis is reversible, but if it is left untreated it can progress to periodontitis, in which the gum and bone supporting the teeth are damaged. Read our guide to gum disease: causes, early signs and treatment.

Flossing too hard or with the wrong technique

Snapping floss down between the teeth or sawing it against the gum can cut the gum and cause bleeding, even when the gums are otherwise healthy. A careful technique (see below) makes this much less likely.

Starting a new flossing routine

When you start flossing again, the first few days of bleeding usually come from gums that were already inflamed. Stopping because of the bleeding allows plaque to build up again, so keep cleaning gently.

Tartar (calculus)

Plaque that is not removed hardens into tartar, which cannot be removed by brushing or flossing. Tartar at or below the gum line keeps the gum irritated. It needs professional cleaning; see deep cleaning vs regular teeth cleaning.

Hormonal changes

During pregnancy, puberty and at some other times, hormonal changes can make the gums react more strongly to plaque, so they bleed more easily. Dental check-ups and cleaning during pregnancy are generally considered safe; tell your dentist that you are pregnant.

Medicines

Blood-thinning medicines, such as anticoagulants and some antiplatelet drugs, can make the gums bleed more easily. Do not stop or change these medicines on your own. Tell your dentist which medicines you take, and speak with your doctor if the bleeding concerns you.

Smoking

Smoking increases the risk of gum disease. It can also reduce gum bleeding, so gum disease in smokers may be more advanced than it looks. Regular gum checks are especially important if you smoke or chew tobacco.

Other health conditions

Less commonly, bleeding gums can be linked to other conditions, such as diabetes, a blood or clotting disorder, or a diet very low in vitamin C. A review of clinical trials found that low vitamin C intake was linked to a greater tendency for gums to bleed (Hujoel and colleagues, 2021). If your gums bleed easily and you also have unexplained bruising, nosebleeds, tiredness or frequent infections, see a doctor as well as a dentist.

How to floss without making your gums bleed

Illustration: snapping floss into the gum can cause bleeding; curving it gently around each tooth cleans the tooth surface with less risk of injuring the gum. Simplified. Not a patient photograph.

1. Use about 45 cm (18 inches) of floss, wound around your middle fingers, with a short section held between your thumbs and index fingers.
2. Guide the floss gently between the teeth with a slow back-and-forth motion. Do not snap it into the gum.
3. Curve the floss into a C-shape around one tooth and slide it gently just under the gum line.
4. Move it up and down against the side of the tooth a few times, then curve it around the neighbouring tooth.
5. Use a clean section of floss for each gap, and floss once a day.

If floss is difficult to use, interdental brushes are a good alternative for many people, and a review of studies found that they may reduce gum inflammation more than floss (Worthington and colleagues, 2019). A water flosser can help some people, especially around bridges, braces or implants; see is a water flosser better than floss?. Brush twice a day with a soft brush and fluoride toothpaste; see our effective brushing techniques and electric vs manual toothbrush.

When to worry about bleeding gums

Illustration: signs that bleeding gums need a dental check. Not a patient photograph.

Book a dental check if:

• your gums still bleed after 3 days of gentle daily brushing and flossing
• your gums are swollen, red, tender or sore
• you have bad breath or a bad taste that does not go away
• your gums look as if they are pulling away from your teeth, or your teeth feel loose (see receding gums: causes and signs)
• you have pus between your teeth and gums
• the gum around a dental implant bleeds, as this can be an early sign of inflammation around the implant and needs a prompt check

See a dentist or doctor promptly if your gums bleed on their own without brushing, if bleeding is heavy or will not stop, or if it comes with unexplained bruising, nosebleeds, tiredness or fever.

What happens at a gum check?

Your dentist examines your gums, measures the space between each tooth and the gum with a thin probe, and checks for bleeding, tartar and loose teeth. X-rays may be taken to look at the bone. If you have gingivitis, a professional clean and better home care are usually enough. If you have periodontitis, deeper cleaning under the gum may be needed; see our deep cleaning and gum disease pages, and our instructions after scaling and deep cleaning. Laser-assisted gum treatment is offered by some clinics, including ADC (see our LANAP laser therapy page); it does not replace thorough cleaning and good daily care.

How to prevent bleeding gums

• Brush twice a day for about two minutes with a soft brush and fluoride toothpaste
• Clean between your teeth every day with floss or interdental brushes
• Do not smoke or chew tobacco
• Eat a balanced diet that includes fruit and vegetables
• Have regular dental check-ups and professional cleaning, as often as your dentist advises

Bleeding gums treatment at ADC, Chandigarh

At ADC – Centre for Restorative and Implant Dentistry, a gum check is part of the examination. The dentist measures your gums, takes X-rays where needed, explains the cause of the bleeding and gives you a written treatment plan and estimate. Learn more on our bleeding gums and gum disease pages. The clinic is in Sector 21, Chandigarh, within easy reach of Mohali, Panchkula and Zirakpur.

Frequently asked questions

Should I stop flossing if my gums bleed?
No. Stopping usually makes the problem worse, because plaque builds up again. Keep flossing gently every day. If the bleeding has not settled within 3 days, see your dentist.

Why do my gums bleed when I floss but not when I brush?
Floss reaches the gum between the teeth, where a toothbrush cannot clean well. Gum inflammation often starts there, so bleeding may only show when you floss.

Does mouthwash stop bleeding gums?
An antiseptic mouthwash may help as an add-on if your dentist recommends one, but it does not remove plaque or tartar and does not replace brushing, cleaning between the teeth and professional cleaning.

Are bleeding gums during pregnancy normal?
Bleeding gums are common in pregnancy because hormonal changes make the gums more sensitive to plaque. Keep up gentle brushing and flossing, and have a dental check; tell your dentist that you are pregnant.

Can bleeding gums be a sign of something serious?
Usually the cause is gingivitis, which can be reversed. Bleeding that does not settle can be a sign of periodontitis (more advanced gum disease) or, rarely, of a medical condition. See a dentist if bleeding lasts more than 3 days, and a doctor if it comes with bruising, nosebleeds or tiredness.

Book a gum check in Chandigarh

This article is general information, not advice for any individual. Please speak with your dentist about your own situation. If your gums bleed when you floss or brush, you are welcome to book a consultation at ADC – Centre for Restorative and Implant Dentistry:

• Online booking: ADC Zoho Bookings
• Phone: +91-708-780-0016
• Email: help@theadc.dental
• Clinic: ADC- Centre for Restorative and Implant Dentistry, 1197, Sector 21B, Sector 21, Chandigarh, 160022, India

Mon–Fri 10:00 AM–6:30 PM; Sat 10:00 AM–5:00 PM; Sunday closed. You can also request a consultation online.

Reviewed by Dr. Mohit Dhawan, MDS (Prosthodontics, Crown & Bridge and Implantology).

References

1. Chapple ILC, Mealey BL, Van Dyke TE, et al. Periodontal health and gingival diseases and conditions on an intact and a reduced periodontium: consensus report of workgroup 1 of the 2017 World Workshop. J Periodontol. 2018 — PubMed 29926944
2. Trombelli L, Farina R, Silva CO, Tatakis DN. Plaque-induced gingivitis: case definition and diagnostic considerations. J Periodontol. 2018 — PubMed 29926936
3. Worthington HV, MacDonald L, Poklepovic Pericic T, et al. Home use of interdental cleaning devices, in addition to toothbrushing, for preventing and controlling periodontal diseases and dental caries. Cochrane Database Syst Rev. 2019 — PubMed 30968949
4. Hujoel PP, Kato T, Hujoel IA, Hujoel MLA. Bleeding tendency and ascorbic acid requirements: systematic review and meta-analysis of clinical trials. Nutr Rev. 2021 — PubMed 33517432
5. NHS. Gum disease — nhs.uk
6. American Dental Association MouthHealthy. Flossing — mouthhealthy.org