Most blood blisters heal on their own within one to two weeks without any special treatment. The single most important thing you can do is leave the blister intact. That raised pocket of trapped blood sits beneath a layer of skin that acts as a natural sterile bandage, protecting the damaged tissue underneath while new skin forms. Your job is to keep it clean, cushioned, and unpopped.
Why You Shouldn’t Pop It
Blood blisters form when something pinches or crushes your skin hard enough to rupture tiny blood vessels in the deeper layers. Blood pools between those layers and creates the dark, raised bump you see on the surface. Unlike a regular friction blister filled with clear fluid, a blood blister contains actual blood, which makes it more vulnerable to infection if the skin barrier breaks.
Popping or draining a blood blister removes that protective roof and exposes raw, damaged tissue directly to bacteria. The risk of infection far outweighs any relief you get from reducing pressure. If the blister pops on its own (which sometimes happens), treat it as an open wound: gently clean it, apply an antiseptic, and cover it with a bandage.
Step-by-Step Home Care
As soon as you notice a blood blister, gently clean the area with mild soap and water. If you caught it early and the spot is still swelling, applying a cold pack wrapped in a cloth for 10 to 15 minutes can limit how large the blister gets and reduce pain.
Once the blister has formed, protect it from further friction or pressure. A simple adhesive bandage works for blisters in low-contact areas. For spots that take repeated rubbing, like your feet or palms, hydrocolloid bandages are a better choice. These thick, gel-based patches absorb moisture, cushion the blister, and come in shapes designed to resist friction and stay in place during movement. Moleskin, the felt-like padding runners use, is another option for foot blisters. Cut a donut shape so the padding surrounds the blister without pressing directly on it.
Change your bandage daily or whenever it gets wet or dirty. Each time, wash the area gently and let it air dry before reapplying a fresh covering. Avoid tight shoes or gloves that press on the blister while it heals.
What To Expect as It Heals
Over the first few days the blister may look dark red, purple, or nearly black. This is normal. Your body gradually reabsorbs the trapped blood, and the color fades from deep purple to brown to yellowish as the pooled blood breaks down. The raised bump flattens, and new skin forms underneath. Most blood blisters resolve completely within one to two weeks, though larger ones can take slightly longer.
Some tenderness is expected for the first few days, especially if the blister is on a weight-bearing area like the sole of your foot. Over-the-counter pain relievers can help if it’s bothersome.
Signs of Infection
Keep an eye on the blister as it heals. An infected blood blister looks red and swollen beyond the blister itself, and the fluid inside shifts from dark blood to white, yellow, or green pus. You may also notice increasing pain rather than gradually decreasing pain, warmth radiating from the area, or red streaks spreading outward from the blister. These signs mean bacteria have gotten in and you need medical treatment, typically a course of antibiotics.
Blood Blisters in Your Mouth
Oral blood blisters are surprisingly common. More than half of cases are triggered by minor trauma: biting your cheek, burning your palate on hot food, or dental work like fillings and cleanings. Steroid inhalers can also cause them. In about half of cases, no clear cause is found, though there’s an association with type 2 diabetes and high blood sugar.
These blisters usually rupture on their own and heal without treatment. If one forms on your palate and is large enough to feel like it’s blocking your throat, a dentist or oral surgeon can cut and drain it safely. For pain relief, a benzydamine mouthwash or spray can ease discomfort, and chlorhexidine mouthwash helps prevent secondary infection while the spot heals. If you get oral blood blisters repeatedly, your doctor may order blood tests to rule out a clotting disorder.
Blood Blisters Under a Nail
A blood blister trapped under a fingernail or toenail, called a subungual hematoma, is a different situation. Slamming your finger in a door or dropping something heavy on your toe can pool blood beneath the nail plate, creating intense throbbing pressure with nowhere to go.
Small ones that aren’t very painful will resolve as the nail grows out. But if the blood pool is large, covers more than half the nail, or the pain keeps getting worse, you need a provider to drain it. This works best within 24 to 48 hours of the injury. The procedure involves making a tiny hole in the nail to let blood escape, which provides almost immediate pressure relief. Do not attempt this yourself, as it carries a real risk of infection or further damage to the nail bed.
You may need more extensive treatment, including removal of the nail, if the nail plate has separated from the bed, the nail is split, or there’s a deep cut involved.
When a Blood Blister Isn’t a Blood Blister
True blood blisters develop after something pinches, crushes, or repeatedly rubs your skin. If you notice a dark, raised bump that appeared without any obvious trauma, it’s worth a closer look. Nodular melanoma, an aggressive form of skin cancer, can look remarkably similar to a blood blister. It typically appears as a firm, raised, discolored growth that may be brown, red, black, or skin-toned.
The key differences: a blood blister has a clear cause (you pinched it, your shoe rubbed it), flattens and fades over one to two weeks, and doesn’t grow. Nodular melanoma grows rapidly over weeks to months, may bleed without being touched, and most of the growth sits below the skin surface like an iceberg. If you have a dark bump you can’t explain that isn’t improving or is getting bigger, get it evaluated promptly. This type of melanoma develops quickly, so early detection matters.