Gingivitis is caused by the buildup of bacterial plaque on your teeth and along the gumline. When this sticky film of bacteria isn’t removed through regular brushing and flossing, it triggers an inflammatory response in the surrounding gum tissue, leading to redness, swelling, and bleeding. While plaque is the primary driver, several other factors can make your gums more vulnerable or worsen the inflammation once it starts.
How Plaque Triggers Gum Inflammation
Your mouth naturally contains hundreds of bacterial species that form a thin film, called a biofilm, on tooth surfaces. In a healthy mouth, these bacteria coexist in balance with your immune system. Problems start when plaque accumulates and the bacterial community shifts. Certain harmful species begin to dominate, disrupting the normal balance. One well-studied organism, Porphyromonas gingivalis, acts as what researchers call a “keystone pathogen.” It evades the body’s defenses and promotes the growth of other disease-causing bacteria, tipping the whole community toward a state that drives inflammation.
Once this shift happens, your immune system responds by sending white blood cells and inflammatory signals to the gum tissue. Blood flow to the area increases, which is why inflamed gums look red and puffy. The tissue becomes fragile, bleeding easily when you brush or floss. At this stage, the damage is entirely reversible. No bone or connective tissue has been lost. But if the plaque remains and the inflammation persists, gingivitis can progress to periodontitis, a more serious condition where the structures supporting your teeth begin to break down.
What Gingivitis Looks and Feels Like
Gingivitis exists on a spectrum. In its mildest form, you might notice a slight color change in your gums, perhaps a deeper pink or reddish hue, with minor puffiness but no bleeding. Moderate gingivitis brings noticeable redness, swelling, and a glazed or shiny appearance to the gums, along with bleeding when a dentist probes the area (or when you brush). In severe cases, the gums are markedly red and swollen, may bleed on their own without any contact, and can develop small ulcerations.
Many people have gingivitis without realizing it, because it’s often painless in the early stages. The most common first sign is blood on your toothbrush or when you spit after brushing. If your gums bleed regularly, that’s not normal, even if it doesn’t hurt.
Hormonal Changes and Gum Sensitivity
Pregnancy is one of the most well-documented hormonal triggers for gingivitis. Elevated estrogen and progesterone levels don’t cause gum disease on their own, but they change how your gum tissue responds to the plaque that’s already there. These hormones stimulate cells in the gums to produce higher levels of inflammatory signaling molecules, essentially turning up the volume on your immune system’s reaction to bacteria. The result is that the same amount of plaque that might cause no visible problems in a non-pregnant person can produce swollen, bleeding gums during pregnancy.
This heightened sensitivity isn’t limited to pregnancy. Puberty, menstruation, menopause, and hormonal contraceptive use can all shift the balance in similar ways. The gums don’t become diseased because of hormones alone. They become less tolerant of bacteria that were previously kept in check.
Diabetes and Blood Sugar
People with diabetes, particularly those with poorly controlled blood sugar, face a significantly higher risk of gum inflammation and its progression to periodontitis. High blood sugar increases the production of harmful molecules called free radicals in gum tissue, ramping up oxidative stress. This damages cells in the gums and amplifies the inflammatory response to bacterial plaque. The relationship runs both directions: gum disease can make blood sugar harder to control, and elevated blood sugar makes gum disease worse.
Low Vitamin C Levels
Severe vitamin C deficiency causes scurvy, which has been associated with bleeding gums for centuries. But research from a University of Washington analysis published in 2021 found that even mildly low vitamin C levels, well above the threshold for scurvy, were linked to increased gum bleeding during gentle probing. Vitamin C plays a key role in collagen production and tissue repair, so when levels drop, the small blood vessels in your gums become more fragile and prone to bleeding. This doesn’t mean vitamin C deficiency causes gingivitis in the way plaque does, but it can make existing inflammation worse and harder for your body to manage.
Medications That Affect Gum Tissue
Certain medications cause the gums to overgrow, a condition called gingival hyperplasia, which creates deep pockets around the teeth where plaque accumulates more easily. Three drug classes are the most common culprits:
- Anti-seizure medications: Phenytoin is the most widely recognized. Roughly half of people taking it develop some degree of gum overgrowth. Other seizure medications, including carbamazepine and valproic acid, carry the same risk at lower rates.
- Blood pressure medications (calcium channel blockers): Nifedipine leads the group, with gum overgrowth occurring in about 38% of users. Diltiazem causes it in roughly 20% of cases, and other drugs in the same class carry smaller but real risks.
- Immunosuppressants: Cyclosporine, used to prevent organ transplant rejection and treat autoimmune conditions, causes gum overgrowth in anywhere from 13% to 85% of patients depending on the study.
The overgrown tissue makes it physically harder to keep teeth clean, trapping bacteria and creating an environment where gingivitis can take hold even with diligent oral hygiene. If you notice your gums growing over your teeth after starting a new medication, your dentist and prescribing doctor can discuss alternatives.
Other Contributing Factors
Smoking is one of the strongest risk factors for gum disease. It reduces blood flow to the gums, impairs the immune response to bacteria, and slows healing. Smokers are also more likely to develop tartar, the hardened form of plaque that can only be removed professionally. Importantly, reduced blood flow can mask early signs of gingivitis by suppressing the bleeding that would otherwise serve as a warning.
Dry mouth, whether from medications, mouth breathing, or medical conditions, removes the protective rinsing effect of saliva, allowing plaque to build up faster. Crowded or crooked teeth create hard-to-reach areas where plaque accumulates. Poorly fitting dental restorations like crowns and bridges can trap food and bacteria at the gumline. Stress weakens the immune system’s ability to fight off the bacteria responsible for gum inflammation.
Genetics also play a role. Some people are simply more prone to an aggressive inflammatory response to plaque, which means they may develop gingivitis faster and more severely than others with identical oral hygiene habits.
How Gingivitis Is Reversed
Because gingivitis involves inflammation without permanent tissue damage, it is fully reversible. The cornerstone is removing the plaque and preventing it from building back up. A professional dental cleaning removes hardened tartar that brushing can’t reach. From there, consistent daily brushing (twice a day for two minutes) and flossing disrupts the bacterial biofilm before it can mature and shift toward harmful species.
Most people see improvement within one to two weeks of consistent oral hygiene after a cleaning. The bleeding stops first, followed by a gradual return to normal color and firmness. If gingivitis doesn’t improve with good home care and professional cleaning, that’s a signal to investigate underlying factors like uncontrolled diabetes, medication effects, or a nutritional deficiency that may be fueling the inflammation.