The short answer: Gum disease is an inflammation of the gums caused by plaque, the sticky film of bacteria that builds up on teeth. Its early stage, gingivitis, causes red, swollen gums that bleed when you brush, and it can be reversed with daily brushing and cleaning between the teeth. Left alone, it can progress to periodontitis, which destroys the gum attachment and bone that hold teeth in place and can lead to loose teeth. Periodontitis is treated with deep cleaning under the gums and sometimes surgery, followed by regular maintenance visits. Bleeding gums are a reason to see a dentist, not to stop brushing.
Gum disease is one of the most common health conditions in the world: the World Health Organization estimates that severe periodontal disease affects more than 1 billion people (World Health Organization, 2025). In the United States, about 4 in 10 adults aged 30 or older have some degree of periodontitis, rising to about 60% of adults aged 65 or older (Centers for Disease Control and Prevention, 2024), and 7.8% have the severe form (Eke et al., 2018).
This guide explains the difference between gingivitis and periodontitis, why gums bleed, the warning signs and risk factors, how dentists diagnose and stage gum disease, which treatments work, and how to prevent it from coming back.
What is gum disease?
Gum disease starts with plaque. If you don’t remove it by brushing and cleaning between your teeth, it builds up and irritates your gums (NHS, 2026). In its early stage, gingivitis, the gums become red, swollen and prone to bleeding; dentists define it mainly by whether the gums bleed when they are gently probed (Chapple et al., 2018). If gingivitis isn’t treated, it can progress to periodontitis, in which the gums pull away from the teeth, pockets form, and the bone and tissue supporting the teeth are gradually destroyed (National Institute of Dental and Craniofacial Research, 2026).
Gingivitis vs. periodontitis: what’s the difference?
Gingivitis affects only the gums, and clinical gum health can be restored once it is treated. Periodontitis involves loss of the attachment and bone around the teeth (Chapple et al., 2018; Tonetti et al., 2018). Not everyone with gingivitis goes on to develop periodontitis, but in susceptible people it can (James et al., 2017), which is why managing gingivitis is considered the first step in preventing periodontitis (Chapple et al., 2015).
Why do my gums bleed when I brush?
The most common reason is gingivitis. Gums that bleed when you brush, floss or eat hard foods are one of the main symptoms of gum disease (NHS, 2026), and daily brushing and cleaning between the teeth can reverse it (Chapple et al., 2015). Because plaque along the gumline is the cause, the fix is more careful cleaning there, not less (NHS, 2026).
Other factors can make gums more likely to bleed. Hormonal changes, such as those during pregnancy, can make gums more sensitive (Mayo Clinic, 2023; National Institute of Dental and Craniofacial Research, 2026). A review of clinical trials found that low vitamin C intake was linked to a greater tendency for gums to bleed (Hujoel et al., 2021), and some illnesses and medicines can also affect the gums (Mayo Clinic, 2023). If your gums bleed heavily or without brushing, tell your dentist or doctor so they can look for other causes.
What are the signs of gum disease?
These are the warning signs to look out for (National Institute of Dental and Craniofacial Research, 2026):
- Red, swollen or tender gums
- Gums that bleed easily, for example when you brush or floss
- Gums that pull away from the teeth
- Loose or sensitive teeth, or pain when chewing
- Bad breath that doesn’t go away
Receding gums are very common: in a US national survey, 91.6% of adults had gum recession on at least one tooth (Romandini et al., 2020). Our guide to bad breath covers the other causes of persistent bad breath.
What causes gum disease, and who is at risk?
Plaque is the direct cause (NHS, 2026), but some people are much more susceptible than others. Tobacco use is the most significant risk factor (National Institute of Dental and Craniofacial Research, 2026): people who smoke have twice the risk of gum disease of people who don’t (Centers for Disease Control and Prevention, 2025). Other risk factors include:
- Diabetes (National Institute of Dental and Craniofacial Research, 2026). The link works both ways, as the section on other health problems below explains.
- Older age and genetics (National Institute of Dental and Craniofacial Research, 2026).
- Hormonal changes in women, including pregnancy (National Institute of Dental and Craniofacial Research, 2026).
- Medicines that cause dry mouth, since saliva helps protect the gums (Mayo Clinic, 2023). See our guide to saliva and dry mouth.
- Stress, poor nutrition and obesity (Centers for Disease Control and Prevention, 2024). Our article on stress and oral health looks at the evidence.
- Some illnesses, such as rheumatoid arthritis and conditions that weaken the immune system (National Institute of Dental and Craniofacial Research, 2026).
How is gum disease diagnosed?
A dentist or hygienist uses a thin probe to measure the spaces between your teeth and gums, called pockets; healthy pockets measure between 1 and 3 millimeters. They also check whether teeth are loose, ask about risk factors such as smoking and diabetes, and may take X-rays to look for bone loss (National Institute of Dental and Craniofacial Research, 2026). Our guide to how dentists find cavities and gum disease early explains these checks in more detail.
What do periodontitis stages and grades mean?
Since the 2017 World Workshop classification, periodontitis has been described by stage and grade. The stage, I to IV, reflects how severe and complex the disease is, based mainly on how much attachment and bone has been lost and whether teeth have been lost to periodontitis: attachment loss of 1 to 2 mm between the teeth is stage I, 3 to 4 mm is stage II, and 5 mm or more is stage III or IV, with stage IV reserved for cases needing complex rehabilitation (Tonetti et al., 2018).
The grade, A to C, estimates how fast the disease is progressing: slow, moderate or rapid. Smoking 10 or more cigarettes a day, or having diabetes with an HbA1c of 7.0% or higher, places someone in the rapid-progression grade C (Tonetti et al., 2018). If you are told you have, for example, “stage III, grade B periodontitis,” it describes both how much damage has been done and how quickly it is likely to progress.
Can gum disease be reversed?
Gingivitis can be: gum health can be restored once the plaque that causes it is controlled (Chapple et al., 2018; Chapple et al., 2015). Periodontitis can be treated and brought under control, and gum health can be restored afterward, but a person who has had periodontitis remains at increased risk of it coming back and needs to be monitored closely (Chapple et al., 2018). Lost bone does not simply grow back, although surgery can regenerate some of it in selected cases (Sanz et al., 2020).
How is gum disease treated?
Early gum disease is treated with oral hygiene advice and a professional clean (NHS, 2026). For periodontitis, the European Federation of Periodontology’s clinical guideline describes a stepwise approach (Sanz et al., 2020):
- Step 1: changing behavior, including better brushing and cleaning between the teeth, removing plaque and tartar above the gumline and controlling risk factors such as smoking and diabetes.
- Step 2: cleaning below the gumline, known as scaling and root planing or deep cleaning, sometimes with additional treatments.
- Step 3: gum surgery for areas that don’t respond to deep cleaning.
- Step 4: supportive periodontal care, regular maintenance visits to keep the disease stable over time.
In severe cases, treatment can also include antibiotics or removing teeth that can’t be saved (NHS, 2026). Prescribed medicines may be used alongside deep cleaning, and surgery may be needed for advanced disease (National Institute of Dental and Craniofacial Research, 2026).
Does mouthwash help gum disease?
A Cochrane review of 51 trials found that a chlorhexidine mouthwash used alongside brushing for 4 to 6 weeks greatly reduced plaque. It also reduced gingivitis, but in people with mild gum inflammation the reduction was too small to be considered clinically relevant, and it caused tooth staining, taste changes and mouth irritation in some users (James et al., 2017). A mouthwash is an add-on to brushing and cleaning between the teeth, not a substitute, and the NHS advises not using it straight after brushing (NHS, 2026).
How can you prevent gum disease?
The same daily habits prevent gum disease and stop it coming back (NHS, 2026):
- Brush twice a day with fluoride toothpaste, and spit rather than rinse afterward (NHS, 2026).
- Clean between your teeth every day with floss or interdental brushes (NHS, 2026). A Cochrane review found that flossing plus brushing may reduce gingivitis compared with brushing alone, and interdental brushes may work better than floss where they fit, although the evidence is of low certainty (Worthington et al., 2019). See our guides to flossing and water flossers.
- Consider a powered toothbrush. Compared with manual brushes, powered brushes reduced plaque by 11% and gingivitis by 6% after 1 to 3 months, and by 21% and 11% after more than 3 months (Yaacob et al., 2014). Our comparison of electric and manual toothbrushes has more.
- Stop smoking. Tobacco use is the most significant risk factor for gum disease (National Institute of Dental and Craniofacial Research, 2026; Centers for Disease Control and Prevention, 2025).
- See your dentist regularly, at the interval they recommend based on your risk (Fee et al., 2020).
For a step-by-step routine, see our daily dental hygiene guide.
Is gum disease linked to other health problems?
Research has linked gum disease with heart disease, diabetes and respiratory disease, although these links don’t prove that gum disease causes them (Mayo Clinic, 2023). The best-studied link is with diabetes: a Cochrane review of 35 trials found that treating periodontitis in people with diabetes lowered HbA1c, a measure of long-term blood sugar, by 0.43 percentage points after 3 to 4 months, based on moderate-certainty evidence (Simpson et al., 2022). For what the research shows on each condition, see how your oral health affects your body.
What it means for you
If your gums bleed when you brush
Keep brushing twice a day, gently but thoroughly along the gumline, and start cleaning between your teeth every day. If the bleeding doesn’t settle, see a dentist, since bleeding gums are a reason to book a visit (NHS, 2026).
If you’ve been told you have periodontitis
Ask what stage and grade it is, follow the treatment steps your dentist or periodontist recommends and keep up maintenance visits afterward, because periodontitis can come back even after successful treatment (Chapple et al., 2018; Sanz et al., 2020).
If you smoke or have diabetes
Both raise your risk and can speed up the disease (Tonetti et al., 2018). Quitting smoking and keeping blood sugar under control are part of treating gum disease (Sanz et al., 2020), and treating your gums may help your blood sugar too (Simpson et al., 2022).
If you’re pregnant
Hormonal changes can make gums more sensitive, and the NHS advises regular dental check-ups during pregnancy (NHS, 2026).
Questions to ask your dentist
- Do I have gingivitis or periodontitis, and if periodontitis, what stage and grade?
- How deep are my gum pockets, and have they changed since my last visit?
- Do I need a deep cleaning, and how many visits will it take?
- Should I see a periodontist (gum specialist)?
- Which interdental cleaner suits the gaps between my teeth?
- How often should I come back for check-ups or maintenance?
When to see a dentist
Book a dental visit if (NHS, 2026):
- Your gums bleed when you brush your teeth or eat hard foods
- Your gums are painful and swollen
- You have bad breath
- Your child has sore, bleeding gums
Ask for an urgent dental appointment if you have gum disease along with very sore and swollen gums, teeth that are loose or falling out, ulcers or red patches in your mouth, or a lump in your mouth or on your lip (NHS, 2026). For other urgent problems, see what to do in a dental emergency.
The bottom line
Gum disease starts as gingivitis, which causes red, bleeding gums and can be reversed with daily brushing and cleaning between the teeth. If it progresses to periodontitis, it destroys the support around the teeth; treatment with deep cleaning, sometimes surgery, and lifelong maintenance can control it. Smoking and diabetes are the biggest risk factors you can act on, and bleeding gums are a reason to see a dentist (Chapple et al., 2015; Sanz et al., 2020; NHS, 2026).
References
Centers for Disease Control and Prevention. (2024). About periodontal (gum) disease. https://www.cdc.gov/oral-health/about/gum-periodontal-disease.html
Centers for Disease Control and Prevention. (2025). Smoking, gum disease, and tooth loss. https://www.cdc.gov/tobacco/campaign/tips/diseases/periodontal-gum-disease.html
Chapple IL, Van der Weijden F, Doerfer C, Herrera D, Shapira L, Polak D, et al. (2015). Primary prevention of periodontitis: Managing gingivitis. Journal of Clinical Periodontology, 42(Suppl 16), S71–S76. https://doi.org/10.1111/jcpe.12366
Chapple ILC, Mealey BL, Van Dyke TE, Bartold PM, Dommisch H, Eickholz P, et al. (2018). Periodontal health and gingival diseases and conditions on an intact and a reduced periodontium: Consensus report of workgroup 1 of the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions. Journal of Clinical Periodontology, 45(Suppl 20), S68–S77. https://doi.org/10.1111/jcpe.12940
Eke PI, Thornton-Evans GO, Wei L, Borgnakke WS, Dye BA, Genco RJ. (2018). Periodontitis in US adults: National Health and Nutrition Examination Survey 2009–2014. Journal of the American Dental Association, 149(7), 576–588.e6. https://doi.org/10.1016/j.adaj.2018.04.023
Fee PA, Riley P, Worthington HV, Clarkson JE, Boyers D, Beirne PV. (2020). Recall intervals for oral health in primary care patients. Cochrane Database of Systematic Reviews, 10(10), CD004346. https://doi.org/10.1002/14651858.CD004346.pub5
Hujoel PP, Kato T, Hujoel IA, Hujoel MLA. (2021). Bleeding tendency and ascorbic acid requirements: Systematic review and meta-analysis of clinical trials. Nutrition Reviews, 79(9), 964–975. https://doi.org/10.1093/nutrit/nuaa115
James P, Worthington HV, Parnell C, Harding M, Lamont T, Cheung A, et al. (2017). Chlorhexidine mouthrinse as an adjunctive treatment for gingival health. Cochrane Database of Systematic Reviews, 3(3), CD008676. https://doi.org/10.1002/14651858.CD008676.pub2
Mayo Clinic. (2023). Periodontitis: Symptoms and causes. https://www.mayoclinic.org/diseases-conditions/periodontitis/symptoms-causes/syc-20354473
National Institute of Dental and Craniofacial Research. (2026). Periodontal (gum) disease. https://www.nidcr.nih.gov/health-info/gum-disease
NHS. (2026). Gum disease. https://www.nhs.uk/conditions/gum-disease/
Romandini M, Soldini MC, Montero E, Sanz M. (2020). Epidemiology of mid-buccal gingival recessions in NHANES according to the 2018 World Workshop Classification System. Journal of Clinical Periodontology, 47(10), 1180–1190. https://doi.org/10.1111/jcpe.13353
Sanz M, Herrera D, Kebschull M, Chapple I, Jepsen S, Berglundh T, et al. (2020). Treatment of stage I–III periodontitis—The EFP S3 level clinical practice guideline. Journal of Clinical Periodontology, 47(Suppl 22), 4–60. https://doi.org/10.1111/jcpe.13290
Simpson TC, Clarkson JE, Worthington HV, MacDonald L, Weldon JC, Needleman I, et al. (2022). Treatment of periodontitis for glycaemic control in people with diabetes mellitus. Cochrane Database of Systematic Reviews, 4(4), CD004714. https://doi.org/10.1002/14651858.CD004714.pub4
Tonetti MS, Greenwell H, Kornman KS. (2018). Staging and grading of periodontitis: Framework and proposal of a new classification and case definition. Journal of Clinical Periodontology, 45(Suppl 20), S149–S161. https://doi.org/10.1111/jcpe.12945
World Health Organization. (2025). Oral health [Fact sheet]. https://www.who.int/news-room/fact-sheets/detail/oral-health
Worthington HV, MacDonald L, Poklepovic Pericic T, Sambunjak D, Johnson TM, Imai P, et al. (2019). Home use of interdental cleaning devices, in addition to toothbrushing, for preventing and controlling periodontal diseases and dental caries. Cochrane Database of Systematic Reviews, 4(4), CD012018. https://doi.org/10.1002/14651858.CD012018.pub2
Yaacob M, Worthington HV, Deacon SA, Deery C, Walmsley AD, Robinson PG, et al. (2014). Powered versus manual toothbrushing for oral health. Cochrane Database of Systematic Reviews, 2014(6), CD002281. https://doi.org/10.1002/14651858.CD002281.pub3
References checked October 2026 · Editorial policy · Report a correction
Discover more from HappyTeeth.Care
One email a month with new guides and one study, explained. Join and get a free printable dental emergency card. No spam, unsubscribe any time.
