Sore gums most often result from plaque buildup along the gumline, which triggers inflammation known as gingivitis. But bacterial buildup is only one of many possible causes. Hormonal shifts, medications, nutritional gaps, tobacco use, and even brushing too hard can all make your gums tender, swollen, or painful.
Plaque Buildup and Gum Disease
Bacteria in your mouth constantly produce a sticky film on tooth surfaces called plaque. When plaque sits on your teeth long enough, it irritates the surrounding gum tissue and causes gingivitis, the mildest form of gum disease. Gums become red, swollen, and bleed easily, especially when you brush or floss. The good news is that gingivitis is reversible with better oral hygiene.
Left untreated, bacteria can spread below the gumline and form what dentists call a periodontal pocket, an abnormal deepening of the space between the tooth and gum. Inside these pockets, bacteria release toxins that worsen inflammation and gradually destroy the bone and tissue supporting your teeth. This advanced stage, called periodontitis, is a chronic condition and a leading cause of tooth loss. Warning signs include gums that pull away from the teeth, loose or sensitive teeth, pain while chewing, and persistent bad breath.
Brushing Too Hard
Aggressive brushing or using a hard-bristled toothbrush can physically damage gum tissue over time, causing the gums to recede and expose tooth roots. Once roots are exposed, you may notice pain or discomfort near the gumline along with sensitivity to hot, cold, and sweet foods. This type of soreness tends to develop gradually and worsen during brushing, flossing, or dental cleanings. Switching to a soft-bristled brush and using gentle, circular strokes instead of a back-and-forth scrubbing motion can prevent further damage.
Hormonal Changes
Fluctuations in estrogen and progesterone can make gums significantly more reactive, even if your oral hygiene hasn’t changed. During puberty, pregnancy, the menstrual cycle, and menopause, elevated hormone levels increase blood flow to the gums and make them more sensitive to plaque. Progesterone in particular increases the permeability of tiny blood vessels in gum tissue, which promotes swelling, bleeding, and inflammation.
These effects are measurable. In roughly 75% of women, fluid in the space between the teeth and gums increases by about 20% during ovulation. Pregnancy gingivitis is especially common because both estrogen and progesterone remain elevated for months, suppressing parts of the immune response and slowing tissue repair. The soreness typically improves once hormone levels stabilize, but it can accelerate existing gum problems if plaque control slips during that window.
Canker Sores
Canker sores are small, shallow ulcers that develop on soft tissue inside the mouth, including at the base of the gums. They’re not contagious and have no connection to the herpes virus. Minor canker sores, the most common type, are small and oval-shaped with a red border. They heal on their own in one to two weeks without scarring.
Major canker sores are deeper, larger, and can be extremely painful. These can take up to six weeks to heal and sometimes leave scars. A rarer type, called herpetiform canker sores, appears as clusters of 10 to 100 pinpoint-sized ulcers that may merge into one large sore. Despite the name, they’re not caused by herpes. Stress, minor mouth injuries (like biting your cheek), acidic foods, and certain nutritional deficiencies can all trigger canker sores.
Medications That Cause Gum Overgrowth
Certain medications cause the gums to grow over the teeth, a condition called gingival overgrowth. The swollen, enlarged tissue becomes tender and can trap food and bacteria, making the problem worse. Three drug classes are the most common culprits: seizure medications (particularly phenytoin), immune-suppressing drugs used after organ transplants (especially cyclosporine), and blood pressure medications in the calcium channel blocker family (such as nifedipine and amlodipine).
The rates are striking. About 50% of people taking phenytoin develop gum overgrowth, roughly 30% of those on cyclosporine, and around 20% of those taking nifedipine. If you notice your gums becoming puffy or starting to cover more of your teeth after starting a new medication, your dentist and prescribing doctor can often find an alternative or adjust your treatment plan.
Smoking and Tobacco Use
Smokers face twice the risk of gum disease compared to nonsmokers, and that risk climbs the more and longer you smoke. Tobacco weakens the immune system’s ability to fight infection in gum tissue, so bacteria do more damage before your body mounts a response. Smoking also impairs healing, which means treatments for gum disease tend to work less effectively in smokers.
One deceptive aspect of smoking is that nicotine constricts blood vessels, which can reduce visible bleeding. Your gums may look less inflamed on the surface even as disease progresses underneath. This can mask early warning signs and delay diagnosis until significant tissue or bone damage has already occurred.
Vitamin C Deficiency
Vitamin C plays a direct role in maintaining gum health. Even moderate depletion can cause gums to bleed, and clinical studies have found that this bleeding occurs regardless of how well you brush and floss. A complete deficiency leads to scurvy, which causes spongy, swollen, bleeding gums and increased tooth mobility.
The recommended daily intake is 90 mg for adult men and 75 mg for adult women. That’s easily reached through a single orange, a cup of strawberries, or a serving of bell peppers. True scurvy is rare in developed countries, but people with very restricted diets, heavy alcohol use, or conditions that impair nutrient absorption may develop subclinical deficiency that shows up in the gums first.
Diabetes
Diabetes and gum disease have a well-documented two-way relationship. High blood sugar creates conditions that favor bacterial growth and impair the body’s ability to fight gum infections. People with poorly controlled diabetes are more prone to periodontitis. Interestingly, the relationship works in reverse too: treating gum disease has been shown to significantly improve blood sugar control compared to no treatment, suggesting that chronic gum inflammation makes diabetes harder to manage.
Dentures and Dental Appliances
Ill-fitting dentures, new braces, retainers, and other oral appliances can rub against gum tissue and cause persistent soreness. Denture wearers are particularly susceptible to a condition called denture stomatitis, which causes swelling, tenderness, and discoloration of the tissue underneath the appliance. Symptoms can include canker sores, cracks at the corners of the mouth, white or red patches on the gums or tongue, and general mouth pain.
Left untreated, the constant irritation can change the shape of the tissue beneath the denture, making the fit even worse over time. Some denture wearers develop small nodules on the roof of the mouth that interfere with the appliance. A dentist can adjust or reline the denture, treat any fungal infection contributing to the inflammation, and in some cases recommend a replacement appliance if the current one no longer fits properly.
Signs That Point to Something Serious
Mild gum soreness after flossing or eating something sharp usually resolves on its own within a few days. But certain patterns suggest a problem that needs professional attention: gums that bleed regularly when you brush, tissue that appears to be pulling away from your teeth, teeth that feel loose or shift position, ongoing pain while chewing, and bad breath that doesn’t improve with better hygiene. These symptoms often develop gradually, which makes them easy to dismiss, but they can indicate bone loss that won’t reverse without treatment.