Dried blood under a toenail, known medically as a subungual hematoma, usually can’t be scrubbed or picked out on its own. The blood is trapped between the nail plate and the nail bed beneath it, so the nail itself acts as a sealed barrier. In most cases, the dried blood either needs to be drained by a healthcare provider (if it’s recent enough), or it simply grows out with the nail over several months.
Why the Blood Is Trapped
A subungual hematoma forms when an injury causes bleeding underneath the hard nail plate. Common causes include dropping something heavy on your toe, stubbing it, or repetitive pressure from tight shoes during running or hiking. The blood pools in the small space between the nail and the nail bed, then dries and darkens as it ages. Because the nail is firmly attached to the tissue beneath it, there’s no easy way to access the dried blood without going through or around the nail.
When the blood first collects, it builds pressure against the nail bed, which is why a fresh hematoma can be intensely painful. Once the blood dries and the pressure stabilizes, the throbbing usually fades, but the dark discoloration remains.
Fresh Hematomas: Draining the Blood
If your injury just happened and the blood is still liquid, a doctor or urgent care provider can relieve the pressure through a procedure called trephination. This involves cleaning the nail and surrounding skin, then creating a small hole through the nail plate using a heated needle or a specialized drill. The trapped blood drains out through the hole, and the pain relief is often immediate.
Trephination works best within the first 24 to 48 hours, while the blood is still fluid. Once it dries and clots, there’s nothing left to drain, and the procedure won’t help. This is why timing matters: if you have a painful, swollen, dark toenail from a recent injury, getting it drained quickly is the most effective option.
Dried Blood: Waiting for It to Grow Out
If the blood has already dried, the most reliable path is patience. Toenails grow slowly, roughly 1.5 millimeters per month, which means a full toenail takes about 12 to 18 months to replace itself completely. The dried blood will gradually move toward the tip of your toe as new nail grows in behind it. Eventually, you’ll trim it away during a normal nail clipping.
During this process, the discolored portion of the nail may look dark brown, black, or reddish-purple. It can also become slightly thickened or textured. This is cosmetically annoying but usually harmless. You don’t need to do anything special to speed it up. Just keep the nail trimmed, wear shoes that give your toes room, and let it grow.
What About Removing It at Home?
You might be tempted to try drilling, scraping, or prying the nail to get the dried blood out. This carries real risks. Puncturing or lifting the nail with non-sterile tools can introduce bacteria into the nail bed, leading to infection. The nail bed itself is delicate tissue, and damaging it can cause the new nail to grow back abnormally, sometimes permanently.
Some people try soaking the toe in warm water to loosen the blood. While warm soaks can feel soothing, they won’t dissolve or dislodge dried blood that’s sealed under the nail plate. The blood is essentially glued in place by the nail above it.
If the nail is already lifting or loosening on its own (which sometimes happens with larger hematomas), keep the area clean and dry. You can use a small adhesive bandage to protect the loose nail from catching on socks or bedding. Don’t force the nail off. Let it separate naturally, and a new nail will grow in underneath.
When Professional Help Makes Sense
A few situations call for a visit to a healthcare provider rather than waiting it out:
- Severe pain that doesn’t improve. Persistent, throbbing pressure under the nail suggests the hematoma may still be fluid enough to drain, or that the nail bed may be more seriously injured.
- The hematoma covers more than half the nail. Larger hematomas are more likely to be associated with damage to the nail bed or even a fracture of the toe bone underneath.
- Signs of infection. Increasing redness spreading beyond the nail, warmth, swelling that gets worse over days, or pus coming from around the nail edges all suggest infection.
- The nail is badly cracked or deformed. A split or shattered nail plate may mean the nail bed needs repair to ensure the nail regrows properly.
Dark Toenail Without an Injury
If you notice a dark streak or discoloration under your toenail but can’t remember injuring it, pay close attention to how it behaves. A hematoma from repetitive pressure (like tight running shoes) typically looks like a bruise or dark smudge, appears relatively quickly, and moves toward the tip of the nail as it grows out. You may notice the blood becoming visible when you trim your nails.
Subungual melanoma, a rare but serious type of skin cancer, can also cause dark discoloration under the nail. It tends to appear as a dark line or streak running lengthwise along the nail rather than a blotchy bruise. It grows slowly over weeks to months, doesn’t move with nail growth the way a hematoma does, and may eventually discolor the skin surrounding the nail (a warning sign called Hutchinson sign). If you see a dark streak under a toenail that wasn’t caused by any injury you can recall, that doesn’t grow out over time, or that seems to be widening, have it evaluated by a dermatologist.
Preventing Future Hematomas
Runners and hikers are especially prone to toenail hematomas because of the repeated impact of toes hitting the front of the shoe. Shoes with a half-thumb’s width of space between your longest toe and the end of the shoe reduce this pressure significantly. Keeping toenails trimmed short and straight across also helps, since a long nail catches more force with each step. Moisture-wicking socks reduce friction, and lacing techniques that hold the heel snug can keep your foot from sliding forward on descents.
For non-athletic injuries, steel-toed footwear in environments where heavy objects could fall is the most straightforward prevention. Even a single dropped can or tool can cause enough force to rupture tiny blood vessels under the nail.