Blood Blisters

For most people, blisters are a mild skin condition and a fairly common occurrence. The friction-type blisters you get on your heel from your shoes rubbing up and down are filled with a clear fluid.

Blood blisters, on the other hand, are raised sacs on the skin that contain blood. Smaller blisters may also be called vesicles, while larger blisters may be referred to as bulla. Most of the time, blood blisters will disappear on their own and do not pose any significant health concerns to you.

Here's what you need to know about this mild skin condition, when and how to care for it, and how to prevent blood blisters from forming.

Common Locations

There are a few areas where blood blisters are likely to pop up. They include:

• Hands
• Fingers
• Feet
• Mouth
• Areas of the body that are subject to excessive friction
• Places where the skin has been pinched (like pinching your finger in a door)
• Close to joints
• Near bony prominences

Symptoms

You’ll be able to distinguish blood blisters from fluid-filled friction blisters, because the raised area will fill with blood as opposed to a clear liquid. When you have a blood blister, deeper layers of the skin are affected, and the cells above the blister die off.

The skin’s blood vessels sustain some mild damage, often dilating as part of an immune response to the dying cells, and inflammation occurs. Initially, the encapsulated blood is a light shade of red, but the hue will darken with time.

Depending on how you acquired the blood blister, you may experience pain at or around the site, and you may notice that inflammation is present. Additionally, blood blisters may be itchy.

Causes

While blood blisters can happen to anyone, they are most common in active people (such as athletes or dancers) and individuals who wear shoes that don’t fit their feet properly. People who have jobs and hobbies that involve manual labor are also at risk of developing blood blisters.

Some of the reasons a person may get blood blisters are as follows:

• The skin is pinched and doesn’t break open.
• The skin is exposed to a high amount of friction, such as when walking, lifting weights, or using a tool.
• Poorly fitted shoes cause excess friction on heels and bony areas of the toes like bunions.
• Feet are more prone to blistering when they are wet—moisture softens the skin and makes it more susceptible to friction.  
• Frostbite might lead to blood blisters.
• People with certain diseases, like kidney failure, may experience blood blisters in the mouth, according to the Indian Journal of Dermatology.
• People taking certain medications, such as blood-thinners, may be more at risk of developing blood blisters.

If you have an unexplained blood blister in your mouth, see your doctor as soon as possible to rule out more concerning causes.

Oral blisters can be brought on by a range of factors, such as an injury from hot food, dental work, and endoscopy procedures. But they can also occur due to serious diseases like rheumatoid arthritis, diabetes, high blood pressure, and, as previously mentioned, kidney failure.

When to Visit a Doctor

Often times, the diagnosis of a blood blister is relatively straightforward. For example, you may discover the formation of a blood blister after you’ve experienced a minor trauma to the skin, such as pinching your finger or the repeated rubbing of your big toe against the side of your shoe.

In many cases, you’ll be able to identify the blood blister, and you won’t require medical intervention or a trip to the doctor as long as you leave the blister alone and give it time to heal.

However, if you discover any of the following, a trip to the doctor might be appropriate to ensure proper healing:

• The pain caused by the blood blister is impeding your ability to do your daily activities.
• The blood blister has emerged for no known reason.
• It shows signs of an infection like redness, swelling, and the feeling of being hot to the touch.
• The blood blister goes away, then proceeds to come back again.
• You find the blister in an unexpected place, such as your mouth, eyelids, or genital region.
• You discover the presence of several blood blisters at once without an apparent cause.
• You have an underlying illness, like diabetes or problems with the circulation, that may make healing more difficult for your body.
• The blister appears following an allergic reaction, burn, or sunburn.

Treatment

As mentioned previously, most of the time, the blister will heal on its own as long as you remove the trauma or repetitive movement that initially caused it.

If your blister causes discomfort, over-the-counter pain relievers like ibuprofen or acetaminophen may be sufficient to ease the pain.

Prevention

Thankfully, the majority of blood blisters, while they may be a bit of an annoyance for a short period of time, will subside in a few weeks. Although there’s no foolproof way to plan for an accidental finger pinch, there are few things you can do to decrease the likelihood of developing a blood blister by other means.

Follow these tips:

• Wear gloves if you plan to work with your hands or use tools or other equipment that requires repetitive motion and would cause friction on your skin.
• Make sure that your shoes fit you properly and that they aren’t causing pressure points on your skin.
• Wear socks with your shoes.
• If you notice that some areas of pressure are forming, you may need to protect your skin with adhesive padding or moleskin until you have broken in your shoes.
• If your feet get sweaty, you may find that placing some powder in your shoes helps to soak up extra moisture.
• Use lubricants on your feet to reduce friction on your skin.
• If your shoes continue to cause painful blood blisters, you may need to consider investing in a new pair.

A Word From Verywell

Generally, you can prevent blood blisters from forming if you use properly fitted hand and footwear. If you happen to acquire a blood blister, they’ll typically heal without causing you a lot of trouble.

However, if blood blisters show up in unusual places and you can’t pinpoint a reason, it’s a good idea to make an appointment with your health care provider to rule out other medical conditions.