Bleeding Gums: Causes, When It Is Normal and When It Signals Disease

Dental plaque — a bacterial biofilm — constantly builds up on the teeth at the gum margin. If it is not removed regularly, the body reacts with inflammation: blood vessels in the gum widen and become more permeable, and the tissue swells, reddens and becomes fragile. As a result, even the gentle touch of a toothbrush, floss or dental probe causes bleeding. This is what we call gingivitis.

It is important that at this stage there is as yet no loss of bone or of the gum's attachment to the tooth. The international periodontal consensus (2017) stresses that gum health can be restored after treatment of gingivitis. That is why bleeding in gingivitis is above all a call to improve hygiene, not a sign of irreversible disease.

The severity of inflammation is, however, also affected by local factors (for example tartar, overhanging fillings, crowded teeth) and general ones (hormones, diseases, medications). Two people with a similar amount of plaque may have quite different degrees of bleeding. This explains why in some people the problem does not go away despite careful brushing and it needs checking whether an additional factor lies behind the bleeding.

From a practical point of view the difference is this. In gingivitis the inflammation is confined to the gum tissue; the teeth are stable, and after hygiene improves the condition returns to normal. In periodontitis the process involves the structures supporting the tooth — attachment and bone are lost, gum pockets form, the gums recede and the teeth may become loose. It is a chronic disease that can be controlled, but destroyed bone cannot be fully rebuilt.

This is one of the most common questions. Overly aggressive scrubbing with a hard toothbrush can damage the gum and lead to its recession, and with poor technique cause minor injuries. In practice, however, most bleeding in people with plaque at the gum margin results from inflammation rather than from mechanical damage. The advice 'brush more gently' is therefore right only in some cases, and more often the problem is too little, not too much, effective cleaning at the gum line.

What does switching to an electric toothbrush give? A 2014 Cochrane review (56 trials, 51 in the analysis, 4,624 participants) showed that powered toothbrushes, compared with manual ones, reduced plaque (SMD −0.50 in the short term and −0.47 in the long term) and gum inflammation (SMD −0.43 in the short term and −0.21 in the long term; moderate-quality evidence), corresponding to roughly 6% and 11% reductions in gingivitis on the Löe and Silness scale. The effect is real, then, but modest — an electric toothbrush is not a miracle solution, and technique and regularity matter more.

Gum bleeding most often begins between the teeth, where the toothbrush does not reach. That is why in people with gingivitis a sensible step is to add cleaning of the interdental spaces — with floss, interdental brushes or a water flosser, depending on the width of the gaps. We discuss the evidence on these tools in detail in our article on the water flosser and floss.

In pregnancy the gums bleed more often because their reaction to dental plaque changes. It is thought that the role of sex hormones is to intensify the inflammatory response to the same amount of plaque. In a meta-analysis covering 20 studies, the prevalence of bleeding on probing in pregnant women was about 67% (95% CI 56–80%), and the prevalence of bleeding and of pockets ≥4 mm rose gradually through pregnancy. The authors noted, however, high heterogeneity between studies and the need for better epidemiological data.

What follows from this? Gum bleeding in pregnancy is very common and is usually reversible gingivitis intensified by hormonal changes, but it should not be dismissed: gingivitis in pregnancy is worth reporting to a dentist, and check-ups planned together with the doctor looking after the pregnancy. Gentle, regular cleaning together with interdental cleaning remains the foundation. Treating yourself with herbal products or rinses without consultation is not a good idea.

The link between the gums and diabetes goes both ways. A meta-analysis of cohort studies (15 studies) showed that people with periodontitis had a higher risk of developing diabetes (summary relative risk 1.26; 95% CI 1.12–1.41), and people with diabetes a higher risk of periodontitis (1.24; 95% CI 1.13–1.37). The authors stressed the high heterogeneity of the studies and the conclusion that people with periodontitis should be screened for diabetes and vice versa.

For someone who notices persistent bleeding and swelling of the gums, this information has a practical side: if the problem keeps returning despite good hygiene, and symptoms such as excessive thirst, frequent urination, tiredness or slow wound healing are also present, it is worth checking blood glucose. People with diagnosed diabetes, in turn, should treat checking the state of the gums as part of diabetes care. We write about diabetes in our knowledge base.

Drugs that affect clotting can intensify bleeding, but they are not its root cause — gingivitis is still the starting point. In a small, randomised, placebo-controlled trial (46 people with healthy periodontium, 7 days), aspirin 325 mg a day moderately increased bleeding on probing in people who already had ≥20% bleeding sites, whereas aspirin 81 mg did not differ significantly from placebo.

For patients taking anticoagulants it is also relevant that periodontal procedures do not appear to carry a particular risk. In a prospective cohort study of 120 people (mean age 75), no significant differences in bleeding were found between people taking direct oral anticoagulants (DOACs) and vitamin K antagonists during and after non-surgical periodontal treatment, and the bleeding events were limited and low-grade. This is an observational study comparing two types of drugs, without a group not taking anticoagulants, so it does not settle everything.

Vitamin deficiencies are sometimes named as a cause of bleeding gums. A 2024 systematic review of 15 studies (including three on hypovitaminosis and gum disease) pointed to a correlation between vitamin deficiencies and oral symptoms, although the authors noted the limits of the evidence. Severe vitamin C deficiency (scurvy) does indeed cause swelling and bleeding of the gums, but today it is rare in people with access to varied food; in most people with bleeding gums the cause is plaque, not a vitamin. Supplementing 'just in case' will not replace hygiene.

Much more rarely, but importantly, bleeding gums can be one of the first signs of a blood disorder. A 2022 integrative review (31 papers, 33 people) showed that the first signs of leukaemia may appear in the mouth, most often in acute myeloid leukaemia (72.7% of the described cases), and typical changes are ulcers, bleeding, ecchymoses, pallor or change of colour of the mucous membranes and areas of necrosis. The data come, however, from case reports, so they do not allow us to estimate how often bleeding gums mean leukaemia — the answer is: very rarely.

At the visit the dentist or hygienist will usually assess the severity of inflammation and the amount of plaque, measure the depth of the gum pockets with a probe, check whether there are signs of periodontitis (ordering X-rays if needed), remove tartar and deposits, show the appropriate cleaning technique and choose interdental tools. A follow-up usually comes after a few weeks to check whether the bleeding has stopped. If it has not, additional causes are looked for or you are referred to a periodontist or doctor.

Remember, too, that the habit that helps the gums most is routine, not a one-off intervention. We write about the effect of the oral microbiome on health in our knowledge base, and about mouthwashes and their limits in our article on antibacterial mouthwash and blood pressure.

Gum bleeding deserves attention, but not panic. In the vast majority of cases it is reversible gingivitis that settles after a few weeks of gentle, regular hygiene and the removal of tartar. The key is not to make two mistakes: not to interrupt cleaning because of bleeding, and not to dismiss bleeding that does not ease or that goes together with general symptoms.

If someone asks us where to start, we answer: with two weeks of consistent cleaning, including of the interdental spaces, and with a visit to the dentist if the effect is weak. The rest — hormones, diabetes, medication, rare blood disorders — comes into play when the basic steps bring no improvement or when worrying accompanying symptoms appear.