Pain along the side of a toenail is almost always caused by an ingrown toenail, where the nail edge digs into the soft skin of the nail fold. This is one of the most common nail problems, affecting roughly 2.5 to 5 percent of adults, and the big toe is by far the most frequent target. Less often, a bacterial infection of the nail fold (called paronychia) can develop on its own, but even that is usually triggered by an ingrown edge, a hangnail, or minor trauma that breaks the skin.
How an Ingrown Nail Causes Pain
Your toenail normally grows forward in a gentle curve, with the edges resting loosely on the skin at each side. When one of those edges curves downward or is cut too short, it can pierce or press into the nail fold. The body treats this like a splinter: it sends blood flow and immune cells to the area, producing the redness, swelling, and tenderness you feel when you press on the side of the toe or put on a shoe.
The condition progresses through three recognizable stages. In the first stage, the side of the toe becomes red and mildly swollen, feels warm, and hurts to the touch, but there’s no pus. In the second stage, redness and swelling increase, and you may notice white or yellow drainage, which signals that a bacterial infection has set in. The third stage involves significant swelling, ongoing pus, and a buildup of raw, bumpy tissue (granulation tissue) that grows over the nail edge. At this point, the surrounding skin can begin to overgrow the nail, and in rare cases a fever develops.
Other Reasons the Side of Your Toenail Hurts
While ingrown nails account for the majority of cases, a few other possibilities are worth knowing about. A bacterial nail fold infection can develop after stubbing your toe, tearing a cuticle, or picking at the skin beside the nail. The most common culprit is Staphylococcus aureus. The hallmark is a red, swollen, tender strip of skin right next to the nail, sometimes with a small pocket of pus underneath. This type of acute infection typically develops within a few days of the initial injury.
A fungal nail infection can thicken and warp the nail plate over time, eventually pushing the edges into the surrounding skin. Subungual hematoma (blood pooling under the nail after a direct hit) can also create pressure that radiates to the sides. And sometimes the answer is simpler than any of these: a shoe that squeezes your toes can reproduce the same side-of-nail pain without any nail abnormality at all.
Why Shoes Matter More Than You Think
Between 63 and 72 percent of people wear shoes that don’t actually match the shape or width of their feet. A narrow or pointed toe box compresses the big toe against the second toe, forcing the nail edge into the skin with every step. Research on forefoot pressure shows that women who switch from pointed or square toe boxes to round, wider ones experience significantly lower pressure at the big toe joint. If your pain flares up during the day and eases when you take your shoes off, footwear is likely a major contributor.
Athletic shoes that are too small create the same problem, especially during activities that push the toes forward, like running downhill or sudden stops in court sports.
What You Can Do at Home
If you’re in the early stage (redness and tenderness but no pus or spreading redness), home care can often resolve the problem. The goal is to reduce swelling, keep the area clean, and gently encourage the nail edge away from the skin.
- Warm soaks. Fill a small basin with lukewarm water and add one to two cups of Epsom salt. Soak the foot for 15 to 20 minutes, up to two or three times per week. The warm water softens the nail and skin, making it easier to work with.
- Lift the nail edge. After soaking, you can tuck a tiny wisp of clean cotton or waxed dental floss under the corner of the nail to keep it from pressing into the skin. Replace it daily.
- Trim correctly next time. Cut your toenails straight across, leaving them long enough so the corners rest loosely against the skin on each side. Don’t round the edges, don’t cut them into a V shape, and don’t trim them too short. Nail clippers, small scissors, or a file all work, so use whichever tool you feel most comfortable with.
- Switch your shoes. Wear open-toed sandals or shoes with a roomy toe box while the nail is tender. Even a few days in better-fitting shoes can significantly reduce pressure on the nail fold.
Over-the-counter nail-softening products containing urea (typically at concentrations above 30 percent) work by breaking down the hard keratin protein in the nail plate, making the nail more pliable and less likely to dig into skin. These can be helpful as a short-term addition to soaking, particularly if your nail is thick or curved.
When Home Care Isn’t Enough
If you see pus, notice the redness spreading beyond the immediate nail fold, or the pain hasn’t improved after a few days of home treatment, the nail has likely reached a stage that needs professional care. People with diabetes or circulation problems in the feet should skip the home treatment phase entirely, because even minor nail infections can escalate quickly when blood flow is compromised.
For a straightforward infection without an ingrown edge, a doctor may drain a small abscess and prescribe a short course of antibiotics. For a persistently ingrown nail, the most effective procedure involves removing a narrow strip (about 3 millimeters) from the side of the nail and then applying a chemical to the exposed nail root to prevent that strip from regrowing. A study of 348 of these procedures found a 99.7 percent success rate over two years, with only a single recurrence. Healing typically takes two to four weeks, and the toe looks and functions normally afterward, just with a slightly narrower nail.
Preventing It From Coming Back
Ingrown toenails have a stubborn habit of recurring on the same toe. The most important change is how you cut your nails: straight across, never shorter than the tip of the toe, and never rounded at the corners. If your nail naturally curves sharply, a podiatrist can show you how to file the edges to reduce pressure without cutting too deep.
Footwear is the other major lever. Choose shoes with a round, wide toe box that doesn’t compress your toes together. If you can wiggle your toes freely inside the shoe, there’s enough room. For athletic shoes, go up a half size if you notice your toes hitting the front during activity. Keeping your toenails dry and your feet clean also reduces the chance of bacterial or fungal infections that can worsen an already vulnerable nail edge.