Why Are My Gums Bleeding? Causes and When to See a Dentist

The usual cause: plaque and gum inflammation

Plaque is a sticky layer of bacteria that forms on teeth every day. Where it is left along the gum line and between the teeth, the gum becomes inflamed: it can look red and swollen and it bleeds easily when brushed. This stage is called gingivitis. Scottish dental guidance (SDCEP) states that gingivitis is reversible with improved self-care¹.

A single bleeding spot is not a diagnosis. A dentist checks for bleeding at many points around every tooth. UK guidance counts gums as healthy when fewer than 10% of those points bleed², and the international definition of gingivitis starts at bleeding at 10% of points or more³. These thresholds come from a dentist's examination, which also looks for damage to the tissues that hold the teeth; they are not a home test. Gums that keep bleeding when you brush are a reason to get them checked.

We cannot give you a timescale for how quickly gums settle once cleaning improves, because we found no reliable source for one. If the bleeding carries on despite careful cleaning, see a dentist.

When gum disease goes deeper

If gum inflammation carries on, it can spread to the tissues and bone that hold the teeth in place. This is periodontitis. Signs can include bad breath, gums that pull back from the teeth and teeth that feel loose, and it may not hurt.

The difference matters because of what can be undone. SDCEP states that damage caused by periodontitis is irreversible but the disease can be stabilised¹. UK prevention guidance describes the bone loss as largely irreversible² and estimates that some level of periodontitis affects almost half of UK adults.

Treatment can restore healthy gums, but people who have had periodontitis remain at increased risk of it coming back⁴ and need regular reviews. How gum disease is treated is explained on the gum disease treatment page.

Other things that can play a part

• Smoking. A review pooling 14 long-term studies found that smokers had about 1.85 times the risk⁵ of developing periodontitis, or of it getting worse, compared with non-smokers.
• Diabetes. UK guidance advises that it is best to assume an increased risk² of gum disease for anyone with diabetes. Well-controlled diabetes is not in itself a risk factor, but control can change over time.
• Medicines. The same guidance notes that some medicines cause a dry mouth, and some, most often calcium channel blockers for blood pressure, can make the gums grow over the teeth. Tell your dentist about every medicine you take, and do not stop a prescribed medicine without asking the doctor who prescribed it.
• Pregnancy. Bleeding gums are common in pregnancy. A review of 20 studies found that about 67 in 100 pregnant women⁶ had gums that bled when a dentist checked them gently with a probe, with large differences between studies.
• Low vitamin C. In a review of 15 trials, vitamin C supplements reduced gum bleeding clearly only in people whose blood vitamin C was low to begin with⁷. In people with normal levels the effect was small. Vitamin C is not a treatment for plaque-related gum disease.
• Other gum conditions. Not all gum problems come from plaque. Some do not clear up when plaque is removed⁴ and can be a sign of a condition elsewhere in the body. This is one reason bleeding that does not settle with good cleaning should be examined.

Stress and diet are often blamed. UK guidance finds the evidence on stress, poor diet and weight insufficient to show a clear link with gum disease.

Is it linked to diabetes or heart disease?

Gum disease and diabetes affect each other. In a Cochrane analysis of 30 trials with 2,443 people who had both periodontitis and diabetes, mostly type 2, treating the gum disease lowered long-term blood sugar (HbA1c) by about 0.4 percentage points after three to four months⁸ compared with no treatment or usual care, at moderate certainty. It supports diabetes care; it does not replace it.

Periodontitis is linked with heart and blood-vessel disease in population studies. That is an association, not proof of cause. A European consensus found insufficient evidence⁹ to say whether treating gum disease prevents heart attacks or strokes. Treat your gums for your gums and teeth, not as heart protection.

What you can do at home

• Keep brushing the areas that bleed. Brush gently along the gum line; stopping lets plaque build up further.
• Twice a day, about two minutes. UK guidance recommends brushing at least twice daily with fluoride toothpaste¹⁰, spitting out the excess rather than rinsing, with a small-headed brush with soft or medium bristles.
• Clean between your teeth every day. Interdental brushes, where they fit, or floss. A Cochrane review found that both may reduce gum inflammation¹¹ when added to brushing, although the evidence is of low certainty and the effects may not be clinically important.
• Mouthwash is not a fix. Chlorhexidine rinse reduces plaque, but in mild gingivitis its effect on the gums was not considered clinically relevant¹², and it stains teeth. Use it only for a short time and only if your dentist advises it.
• If you smoke, stopping helps your gums and makes treatment work better.

If the bleeding keeps coming back despite careful cleaning, see a dentist rather than waiting for it to stop.

When to see a dentist

The NHS advises seeing a dentist if your gums bleed when you brush or eat hard food¹³, if they are painful or swollen, or if you have bad breath. A dentist can find out whether it is gingivitis or periodontitis, remove hardened plaque (tartar) and show you where your cleaning misses.

Ask for an urgent appointment if you have:

• very sore and swollen gums
• teeth that are loose or falling out
• ulcers or red patches in the mouth
• a lump in your mouth or on your lip
• a child with sore, bleeding gums

Emergencies. Call 112 or go to the nearest emergency department if you:

• find it hard to breathe, speak or swallow¹⁴
• have a swollen or painful eye, sudden problems with your eyesight, or swelling in your neck¹⁵
• have a lot of swelling inside your mouth
• find it hard to open your mouth

Frequently asked questions