If you ever notice a large, swollen, and discolored bump on your hand that appeared after an injury or pressure, you might be looking at a blood blister. A blood blister is a pocket of fluid trapped beneath the skin, but instead of the clear fluid typically found in regular blisters, it’s filled with blood. This happens when the skin suffers trauma that breaks small blood vessels, or capillaries, underneath the surface without actually cutting through the outer layer of the skin. The result is a raised area that appears red, dark purple, or even black, and it often causes pain or discomfort, especially when pressure is applied or the blister is located in an area of frequent use.

While blood blisters might look alarming, they are generally harmless and tend to heal on their own within about a week, as long as they’re properly cared for. The healing process involves the body gradually reabsorbing the trapped blood, which reduces the swelling and allows the skin to return to normal. It’s crucial not to pop or puncture a blood blister, no matter how tempting it may be. Doing so increases the risk of introducing bacteria into the wound, which can lead to infection and slow down the natural healing process. If the blister is in a location that’s constantly rubbing against clothing or objects, it may help to cover it loosely with a sterile bandage or gauze to prevent further irritation.

Make sure the area stays clean by gently washing it with mild soap and water, and avoid applying harsh substances that could irritate the skin. You should also avoid any excessive movement that could put strain on the blistered area, as this might cause the blister to rupture. If the blister accidentally breaks on its own, carefully clean the area, apply an over-the-counter antibiotic ointment, and cover it again with a clean dressing to protect it as it heals. Most blood blisters heal without the need for medical treatment, but you should keep an eye on it for any signs of infection. If the skin around the blister becomes increasingly red, warm, swollen, or starts to ooze pus, or if you develop a fever, it may be a sign of infection that requires medical attention.

Additionally, if the blister is especially large or located in a spot where it makes daily tasks difficult, you may want to consult a healthcare provider for guidance. While most blood blisters are caused by direct trauma—like getting your hand caught in a door, pinching your skin, or prolonged friction from tools or sports equipment—it’s worth noting that if you start getting blood blisters frequently and without an obvious reason, it could point to a more serious underlying health issue. Conditions that affect blood clotting, immune function, or skin integrity can sometimes cause spontaneous blood blisters.

If this happens, it’s a good idea to see a doctor for a proper evaluation. People with diabetes, poor circulation, or compromised immune systems should be particularly cautious with any kind of blister, as their risk of infection or delayed healing is higher. Prevention is often the best medicine. Wearing protective gloves when working with tools, avoiding repetitive hand movements that create friction, and being mindful of potential injury can go a long way in preventing blood blisters. Keeping your hands moisturized and well-cared for also helps maintain skin resilience. Although they can be painful and unsightly, blood blisters are usually nothing more than a minor inconvenience. By understanding what they are, how they form, and how to take care of them, you can avoid unnecessary complications and support a quick recovery. And remember, if anything about a blister seems unusual or concerning, it’s always best to consult a medical professional to ensure you’re taking the right steps.