Understanding Subungual Hematoma: A Complete Patient Guide

A subungual hematoma is blood trapped under a fingernail or toenail, usually after the nail is crushed or struck. It often causes dark discoloration and pressure-like pain, and while many cases improve on their own, some need medical evaluation to relieve pain or check for a deeper injury.

Overview: what a subungual hematoma is

A subungual hematoma is a collection of blood trapped beneath a fingernail or toenail. It usually develops after a crush injury, a heavy object falling on the digit, a door closing on the finger, or repeated pressure from sports or tight shoes. The trapped blood creates a dark patch under the nail and may cause throbbing pain because pressure builds in a small enclosed space.

Although the appearance can be dramatic, a subungual hematoma is often a straightforward injury. In many cases, the nail remains in place and the discoloration gradually grows out with the nail over weeks to months. The main questions are whether pain is significant, whether the nail bed underneath may be cut or damaged, and whether there could also be a fracture in the fingertip or toe.

Patients sometimes worry that the dark area means infection or a skin cancer. Trauma-related discoloration is a common cause of a dark nail, but the pattern and history matter. If there has been no injury, or if the spot does not move outward as the nail grows, a doctor may consider other causes of nail discoloration, including nail disorders that need a closer examination.

Symptoms and how it looks

The most recognizable sign of a subungual hematoma is a red, maroon, purple, dark brown, or black area beneath the nail. The color may start lighter and become darker over the first day or two. Depending on how much blood has collected, the involved area may cover just a small portion of the nail or most of it.

Pain is another common symptom. Some people feel mild tenderness, while others describe strong throbbing or pressure, especially soon after the injury. The fingertip or toe may also swell, feel bruised, and be sensitive to touch. Walking can be uncomfortable when a toenail is affected, and using the hand may be difficult if a fingernail is involved.

Sometimes the nail becomes cracked, partially lifted, or loose. If the injury was more forceful, there may be a cut around the nail, visible deformity, or trouble moving the finger or toe. These signs can suggest a more complex injury involving the nail bed or the underlying bone and should not be ignored.

Causes and risk factors

The usual cause of subungual hematoma is direct trauma. Common examples include slamming a finger in a door, dropping something heavy on a toe, striking the nail with a tool, or stubbing the toe. Repetitive microtrauma can also cause it, especially in runners, hikers, soccer players, and people who wear tight footwear for long periods.

Some factors make this injury more likely or more noticeable. Poorly fitting shoes, long-distance running, contact sports, and certain jobs involving manual tools can increase risk. People taking blood-thinning medication or those who bruise easily may develop larger collections of blood after relatively minor trauma, although the mechanism is still the same: bleeding under the nail plate.

Not every dark nail is a subungual hematoma. Fungal infection, pigment changes, inflammatory nail disease, and rarely melanoma can also change nail color. A doctor may look more closely if the discoloration appears without a clear injury, extends into the surrounding skin, recurs in the same place, or does not move out as the nail grows.

How doctors diagnose it

Diagnosis usually begins with the story of the injury and a physical examination. A doctor checks the color and size of the discoloration, the amount of pain, whether the nail is stable, and whether there are cuts around the nail fold. They will also assess blood flow, sensation, and movement in the injured finger or toe.

If the injury was forceful, an X-ray may be recommended to look for a fracture of the fingertip or toe bone. This is especially helpful when there is marked swelling, deformity, severe tenderness, or limited movement. In children, athletes, or anyone with a crushed digit, imaging may be part of a careful evaluation even if the nail itself seems intact.

The doctor also considers whether the nail bed underneath may be torn. In some cases, the nail can stay in place even when there is an underlying laceration. If the appearance is unusual or the history is not typical for trauma, a specialist may evaluate for other causes of nail discoloration, including skin and nail conditions such as skin cancer when clinically appropriate.

Treatment options and what to expect

Treatment depends on pain, the size of the hematoma, and whether there are associated injuries. A small subungual hematoma that causes little pain may need only supportive care. This usually includes rest, protecting the digit, applying ice wrapped in cloth for short periods, and elevating the hand or foot to reduce swelling. Over time, the trapped blood is not removed by the body immediately; instead, the nail gradually grows out and the discoloration moves forward.

When pain is significant, a doctor may recommend draining the blood through a small opening in the nail. This procedure, often called nail trephination, can quickly relieve pressure. It is generally done in a clean medical setting and is most useful soon after the injury while the blood is still fluid enough to drain. Patients should not try to do this at home with heated objects or sharp tools because this can cause burns, infection, and additional nail-bed damage.

If the nail is severely split, lifted, or if there is a deep nail-bed laceration, more involved treatment may be needed. This can include repair of the nail bed and management of any associated fracture, sometimes within orthopedic surgery or hand and foot trauma care pathways. Wound care, pain management, and temporary protection with dressings or splints may also be part of treatment.

Even after appropriate care, the nail may look irregular for a while. A damaged nail can loosen and fall off, and a new nail may take months to grow back fully. If the growth area of the nail was injured, some ridging or shape change can persist, though many people recover with a normal or near-normal nail.

Home care, recovery, and self-care tips

For minor injuries, early self-care can reduce discomfort. Resting the injured hand or foot, applying ice for short intervals, and elevating the area above heart level can help during the first day or two. Over-the-counter pain relief may be used if appropriate for the patient, following a doctor’s or pharmacist’s guidance.

The nail should be kept clean and protected. If there is a small break in the skin, a simple bandage may help prevent rubbing. Tight shoes should be avoided if a toenail is affected, and activities that repeatedly strike the nail should be limited until the pain settles. Patients should not cut away attached nail tissue or attempt to drain the blood at home.

Recovery time varies. Pain often improves within days, especially if pressure is relieved. The discoloration, however, can remain much longer because nails grow slowly. Fingernails often recover faster than toenails. If the nail becomes increasingly red, warm, swollen, or starts draining pus, medical review is important to check for infection.

Prevention and protecting the nails

Many subungual hematomas are accidental, but some can be prevented with simple habits. Wearing properly fitting shoes with enough toe room is especially important for runners, hikers, and people who spend long hours on their feet. Protective footwear may reduce the chance of crush injuries at work or during certain activities.

For hand protection, gloves designed for manual work or sports can lower the risk of direct impact. Keeping nails trimmed can also help reduce catching, lifting, and repetitive trauma. In sports that involve sudden stops or downhill movement, attention to shoe fit and lacing technique can reduce repeated pressure on the toes.

People who have recurring nail injuries or persistent nail pain should consider a medical assessment rather than assuming every dark nail is just bruising. Persistent problems may point to gait issues, footwear problems, repeated trauma, or an underlying nail condition that would benefit from specialist care, sometimes involving dermatology evaluation.

When to seek medical care

Medical care is recommended if pain is intense, the discoloration involves a large part of the nail, or the injury followed a strong crush or impact. A doctor should also assess any nail that is partly detached, any cut around the nail, or a finger or toe that looks misshapen, numb, or hard to move. These features may signal a fracture or a nail-bed injury that needs more than simple home care.

It is also wise to seek care if the injury is in a child, if the patient has diabetes, poor circulation, or an immune system condition, or if there are signs of infection such as spreading redness, warmth, pus, or fever. If there was no clear trauma, or if the dark mark does not grow out with the nail, further evaluation is important to rule out other causes.

In a hospital setting, care may involve emergency assessment, imaging, wound repair, and follow-up with relevant specialists. Where appropriate, emergency medicine and multidisciplinary teams can evaluate painful nail injuries, fractures, and nail-bed trauma. Acibadem International’s multidisciplinary specialists in JCI-accredited hospitals also diagnose and treat nail and fingertip injuries for international patients.

Frequently asked questions

Will a subungual hematoma go away on its own?

Many small subungual hematomas improve without a procedure. The pain usually settles first, while the discoloration gradually moves outward as the nail grows. This can take weeks for fingernails and often longer for toenails.

Does every subungual hematoma need to be drained?

No. Drainage is mainly considered when pressure causes significant throbbing pain or when a doctor believes it will improve comfort. Smaller, less painful injuries are often managed with observation and supportive care.

Can the nail fall off after a subungual hematoma?

Yes, especially if the injury was strong or the nail was partly lifted. If that happens, a new nail usually grows back, but the process can take several months. The final appearance depends on whether the nail growth center was injured.

Is it safe to drain blood under a nail at home?

It is not recommended. Home attempts can cause burns, introduce infection, or damage the nail bed. A medical professional can assess whether drainage is appropriate and perform it in a safer, cleaner way.

How can someone tell the difference between a bruise under the nail and something more serious?

A subungual hematoma usually follows a clear injury and gradually grows out with the nail. If there was no trauma, if the mark changes unpredictably, spreads into the surrounding skin, or does not move outward over time, medical evaluation is important.

Should an X-ray be done for a nail injury?

Sometimes. An X-ray may be recommended when the injury was forceful, pain is severe, the finger or toe is swollen or deformed, or there is concern about a fracture. The decision depends on the exam and the details of the injury.

References

• American Academy of Orthopaedic Surgeons
• American Academy of Dermatology
• Merck Manual Professional Edition
• National Health Service
• Mayo Clinic

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.