Ingrown fingernails happen when the edge or corner of a nail grows into the surrounding skin, causing pain, swelling, and sometimes infection. While ingrown toenails get most of the attention, fingernails develop the same problem through a slightly different set of triggers. The most common cause is improper trimming, but nail biting, trauma, inherited nail shape, and certain medications all play a role.
How a Nail Becomes Ingrown
The basic mechanism is straightforward: a sharp edge or spike of nail presses into the soft skin fold alongside it. As the nail continues to grow, that spike anchors deeper into the tissue and eventually breaks through the skin. Once it penetrates, your body treats it like a foreign object, triggering inflammation, redness, and pain. If bacteria enter the opening, infection follows.
Nails that curve more sharply from side to side are especially prone to this. A hard, over-curved nail plate exerts constant pressure on the skin fold, and any external force (bumping your finger, gripping something tightly) pushes the nail edge further into the tissue.
Improper Nail Trimming
Cutting your nails too short or rounding the corners too aggressively is the single most common cause. When you try to “round off” the corners, you can inadvertently create tiny barbs or spicules, small spikes of nail that are invisible to the naked eye but sharp enough to dig into skin. The soft tissue around the trimmed corner then presses inward, and when the nail regrows, it has nowhere to go but into the skin fold.
Dermatologists recommend trimming nails straight across the top with only a slight curve at the tip. The key is to avoid cutting the corners close to the skin. Leaving a small visible edge of nail at each corner prevents the regrowth from burrowing into the surrounding tissue.
Nail Biting and Picking
Chronic nail biting is a major cause of ingrown fingernails specifically, since it doesn’t affect toenails. Biters typically present with abnormally short, uneven nails, ragged cuticles, and nail folds in various stages of healing. When you tear a nail with your teeth rather than cutting it cleanly, the result is a jagged edge perfectly shaped to catch on the skin fold as it grows back.
The damage goes deeper than cosmetics. Chronic nail biters can experience partial or complete loss of the nail plate, exposing the nail bed underneath. When that happens, the nail bed hardens and thickens, leading to irreversible shortening of the nail plate. The shortened, thickened nail is more likely to grow at an angle that digs into surrounding skin.
Habitual picking at nails and cuticles causes similar problems. Repeated trauma to the nail’s growth center (the matrix, located just beneath the cuticle) can produce permanent changes: transverse ridges, thinning, and generalized distortion of the nail shape. These changes often don’t reverse even after the picking stops.
Trauma and Repetitive Injury
A single injury, like slamming your finger in a door or catching a nail on something, can crack the nail plate or shift its alignment. Even if the nail looks fine afterward, the damage to the growth center may cause the new nail to grow with an irregular edge that angles into the skin fold.
Repetitive minor trauma matters too. People whose work involves frequent hand impacts, gripping tools, or pressing fingertips against hard surfaces subject their nails to ongoing micro-injuries. Over time, these small insults reshape the nail plate or cause the skin fold to swell, narrowing the channel the nail grows through.
Inherited Nail Shape
Some people are born with nails that curve more dramatically from side to side. The most extreme version of this is pincer nail deformity, where the nail’s curvature increases toward the fingertip, causing the edges to dig down into the skin on both sides. This condition runs in families with an autosomal dominant inheritance pattern, meaning if one parent has it, roughly half their children will too. Researchers have documented it across multiple generations, with symptoms typically appearing in the teens and early twenties.
Even without full pincer nail deformity, naturally wide nail plates or nails with a strong transverse curve increase your baseline risk. These shapes leave less clearance between the nail edge and the skin fold, so any additional trigger (a bad trim, minor swelling from an injury) is more likely to tip things into ingrown territory.
Medications That Affect Nail Growth
Certain cancer treatments are well-known triggers. Drugs that block a protein called epidermal growth factor receptor, used in some lung and colorectal cancers, frequently cause inflammation of the nail folds. The swelling, redness, and sometimes excessive tissue growth around the nails can mimic or directly cause ingrown nails on both fingers and toes. This side effect is common enough that oncologists have a name for the cluster of skin reactions these drugs produce.
Oral retinoids, sometimes used long-term for skin cancer prevention, can also dry out the skin around the nails and trigger inflammation of the nail folds. The resulting changes in skin texture and nail pliability make ingrowth more likely.
Underlying Health Conditions
Diabetes increases the risk through two pathways. First, people with diabetes are more prone to bacterial and fungal nail infections, which thicken and distort the nail plate. Second, the reduced blood flow that often accompanies diabetes impairs nail health over time, producing thicker, more brittle nails that are harder to trim properly and more likely to grow into surrounding tissue.
Excessive sweating softens the skin around the nails, compromising its integrity and making it easier for even a mildly curved nail edge to push through. This is particularly common in adolescents. Fungal nail infections have a similar effect: they thicken and warp the nail plate, changing its shape enough to redirect growth into the skin fold.
What an Ingrown Fingernail Looks and Feels Like
Ingrown nails progress through three recognizable stages. In the first stage, you’ll notice mild redness, slight swelling, and pain when you press on the nail fold. At this point, the nail edge is irritating the skin but hasn’t broken through it yet.
In the second stage, the area becomes noticeably swollen and red, and you may see discharge. A local infection has set in. The pain shifts from pressure-dependent to more constant.
In the third stage, the body produces granulation tissue, a mound of raw, red, bumpy tissue that bleeds easily, alongside significant swelling of the skin fold itself. This stage involves active infection and won’t resolve without treatment.
Treatment Options
Mild to moderate ingrown fingernails often respond to conservative care at home. Soaking the finger in warm water for 10 to 20 minutes softens the skin and nail, after which you can gently place a small wisp of cotton under the ingrown edge to lift it away from the skin fold. A topical antibiotic ointment helps prevent infection while the nail grows out past the trouble spot.
When conservative care fails or the ingrown nail keeps coming back, a minor procedure to remove part of the nail and destroy the corresponding section of the growth center is more effective at preventing recurrence. This can be done with a chemical applied to the nail matrix or with a small cautery device. The goal is to permanently narrow the nail so the problematic edge never regrows. Recovery is generally straightforward, and research shows no benefit to taking antibiotics after the procedure.
Preventing Recurrence
The most impactful change is how you trim your nails. Cut straight across, leaving the corners slightly longer than the surrounding skin. Use sharp, clean nail clippers rather than tearing or biting. If you’re a nail biter, addressing that habit is essential, since the uneven edges it creates are a persistent source of new ingrowns.
Keep your nails at a moderate length. Too short and the skin fold closes over the edge; too long and the nail is more vulnerable to catching and tearing. If you have naturally curved nails or a family history of pincer nails, regular trimming on a consistent schedule prevents the nail from ever getting long enough for the curve to press into skin.