Bumps on the inside of your lip are almost always harmless. The most common causes are mucous cysts (mucoceles), canker sores, Fordyce spots, and irritation fibromas. Each one looks and feels different, and most resolve on their own or with simple treatment. Here’s how to figure out what you’re dealing with.
Mucoceles: Fluid-Filled Bumps
A mucocele is the single most common bump found on the inner lip, especially the lower lip. It forms when a tiny salivary gland duct gets damaged or blocked. Saliva that can’t drain normally pools in the surrounding tissue, creating a dome-shaped, painless swelling that can appear seemingly overnight and grow quickly. You have hundreds of minor salivary glands lining the inside of your mouth, and it only takes a small injury, like accidentally biting your lip, to trigger one.
Mucoceles range from about 1 millimeter to 4 centimeters across. Shallow ones look bluish or translucent, almost like a blister filled with clear fluid. Deeper ones blend in with the pink color of your surrounding tissue, making them harder to identify visually. They feel soft and squishy, don’t hurt when you press on them, and move freely under the skin. Many mucoceles rupture on their own, drain, and disappear within a few weeks. The catch is they often refill and come back.
If a mucocele keeps recurring or bothers you, a dentist or oral surgeon can remove it. The three standard approaches are surgical excision with a scalpel, laser removal, and a minimally invasive technique called micro-marsupialization (where a small opening is created to let the cyst drain). Recurrence rates are similar across all three methods. Laser removal tends to cause less bleeding, less pain, and less risk of damaging nearby structures. Micro-marsupialization is especially popular for children because it’s quick and nearly painless.
Canker Sores
If your bump is actually an open, shallow sore that stings, you’re likely dealing with an aphthous ulcer, better known as a canker sore. These are round or oval, typically white or yellowish in the center with a red border, and they hurt, particularly when you eat acidic or salty foods. They’re not contagious and not caused by a virus (that’s cold sores, which appear on the outside of the lip).
Minor canker sores, the most common type, measure 2 to 5 millimeters across and heal on their own in 4 to 14 days without scarring. Major canker sores are larger (1 to 3 centimeters), sit deeper in the tissue, and can last anywhere from 10 days to 6 weeks. Stress, minor mouth injuries, hormonal changes, and certain food sensitivities are common triggers. Over-the-counter topical gels can ease pain while you wait them out.
Fordyce Spots
If you’re noticing clusters of tiny, pale or yellowish dots rather than a single bump, those are likely Fordyce spots. These are oil glands that are visible through the thin skin inside your mouth. They’re completely normal. Between 70% and 80% of adults have them. They don’t hurt, don’t grow, don’t spread, and don’t need treatment. Many people first notice them while examining a different concern and then worry they’re something abnormal. They’re not.
Irritation Fibromas
A fibroma is a firm, smooth bump that develops from repeated irritation in one spot. The classic location is the inside of the cheek right where the upper and lower teeth meet, but they also appear on the inner lip. Chronic cheek-biting or lip-biting is the usual cause. Unlike mucoceles, fibromas feel solid rather than soft and squishy. They’re typically the same color as the surrounding tissue, painless, and don’t change size once they form. A dentist can remove one if it’s in a spot where you keep biting it, but they’re harmless.
Allergic Reactions
Sometimes bumps or swelling on the inner lip come from direct contact with an allergen. The list of potential culprits is surprisingly long: toothpaste ingredients (including mint), lip balms, lipstick, certain foods (nuts, cinnamon, citrus, mango, pineapple), dental materials, and even metals from orthodontic appliances or utensils. Nickel and cobalt are among the most common contact allergens tied to lip inflammation.
Allergic lip reactions can look like generalized swelling, small bumps, or cracked and inflamed tissue. If you recently switched toothpaste, started a new lip product, or ate something unusual before the bumps appeared, that’s a strong clue. Stopping exposure to the allergen usually resolves the problem within days.
HPV-Related Growths
Human papillomavirus can occasionally cause growths inside the mouth. These look different from mucoceles or fibromas. Squamous papillomas, the most common type, appear as small finger-like or cauliflower-textured projections, usually pink to white, typically under 5 millimeters, and usually solitary. Common warts (verruca vulgaris) can also appear inside the mouth as pink-to-white bumps with a rough surface. These growths are generally benign but should be evaluated by a dentist or doctor, who may recommend removal.
When a Bump Could Be Serious
The vast majority of inner lip bumps are benign, but a few features should prompt you to get checked sooner rather than later. Any sore or growth on the lip that lasts more than two weeks without healing deserves professional evaluation. The same goes for any new growth or unusually colored area that doesn’t resolve within a few weeks. Hard, fixed lumps that don’t move, lumps that keep growing, numbness in the area, or unexplained bleeding are also signs to take seriously. Lip cancer is uncommon, but it’s highly treatable when caught early.
For most people, a bump on the inside of the lip turns out to be a mucocele that popped up after an accidental bite, a canker sore triggered by stress, or Fordyce spots that were always there. A dentist can usually identify the cause with a quick visual exam and let you know whether it needs treatment or just time.