Bruises: Causes and Treatments

Skin Problems Image Gallery In 2002, President Bush choked on a pretzel, fainted and suffered an abrasion on his cheek and a bruise on his lower lip. Later in his presidency, he escaped bruising when he dodged a flying shoe. See more pictures of skin problems.
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Ouch! You weren't looking where you were going and rammed your thigh into the edge of your dining room table. Or, you were biking and moved into a turn too quickly, and took a spill. Or, you were throwing the ball around and instead of it falling into your glove, it hit your arm. Lots of mishaps can result in the formation of a bruise. Although the pain might last for only a couple of minutes, you'll be wearing that ugly bruise as a reminder of your blunder for a while. But what causes your skin to turn back and blue?

Basically, a bruise, or contusion, as it's referred to in the medical world, appears when blood vessels break due to a blow to the skin. Blood leaks out of these vessels resulting in a red, purple or black mark on your skin. Sometimes your skin can become raised when the blood from these vessels leaks into the surrounding tissues. In most healthy individuals, your body eventually will reabsorb the blood, and the bruise will disappear. In general, the harder your bump or blow, the larger your bruise will be, and arms and legs are the most typical areas for bruises.


Aside from smarting a bit and being unattractive reminders klutziness, most bruises are pretty harmless. But there are some serious medical conditions that bruising can indicate. We'll let you know what those conditions are on the next few pages.

So, how do bruises form? Why do they change color? How can you make them go away faster? If you're someone who bruises easily, you're probably aching to learn the answers to these questions -- in addition to that bigger question: Why do I bruise more easily than other people?


Why Bruises Form and How They Heal

Like we mentioned before, bruising appears when tiny blood vessel, or capillaries, break due to a blow to the skin. The appearance of a bruise changes over time, and you can tell how old a bruise is and where it is in the process of healing by observing its color. Generally, your skin should look normal again in about two to three weeks after an injury.

  • When a bruise is brand new, it will appear reddish due to the color of the blood that leaked from the capillaries under the skin.
  • At one to two days old, a bruise will take on a bluish or purple color. The swelling at the site of the bruise will cause oxygen to be cut off, and hemoglobin, the substance that carries iron in your blood, will turn blue.
  • At six days old, a bruise will turn a greenish color as the hemoglobin breaks down and the area begins to heal itself.
  • At eight to nine days old, a bruise will then turn yellow or brown. This is the final stage in the body's re-absorption of the blood.

But what do you do if your bruise doesn't change color or heal properly? If the bruise remains firm and gets bigger or more painful, a hematoma may have formed. This happens when blood collects under the skin or in the muscle, and instead of trying to fix this, your body walls the blood off. If this happens, you need to have the hematoma drained by a doctor.


A less common reason for a bruise to stick around is that your body has deposited calcium around the area of your injury. This is called heterotopic ossification and it causes the area of your bruise to become firm and tender. You doctor will be able to identify a heterotopic ossification through X-ray.

In general, bruises at their worst are momentarily painful and an eyesore for a week or two. But sometimes bruising can indicate dangerous medical conditions. Read on to learn when you should worry about a bruise.


When to Worry About a Bruise

Northampton soccer player Ian Sampson  with a black eye
Shaun Botterill/Getty Images

Most of us have had to deal with a bruise when we bump into something or take a spill. But what are some less common reasons for bruising? If you encounter any of the following types of bruising, you should consult a health care professional immediately.

  • Petechiae, or small, 1 to 3 millimeter areas of blood that accumulates under the skin. They look like little red dots and are most commonly found on the legs. Petechiae could indicate serious health problems such as infection in the valves of the heart or abnormal blood clotting platelets.
  • Bruising around your navel can be an indication of bleeding in the abdomen.
  • Bruising behind your ear, also called Battle's Sign, can indicate a skull fracture.
  • Multiple bruises that are raised and firm that appear without any injury can suggest autoimmune diseases in which the body attacks its own blood vessels. In this case of spontaneous bruising, you definitely should consult a medical professional.

Also, if you begin to feel a lot of pressure or pain in a bruised part of your body, you could be suffering from compartment syndrome. This happens when pressure increases on the soft tissue and structure underneath your skin and reduces the flow of blood and oxygen to tissues. This condition could be life threatening, so be sure to contact a medical professional immediately.


You should also contact a doctor if the area of the bruise indicates signs of infection such as streaks of redness, fever or drainage.

On the next page, we'll talk about factors that can increase your likelihood for bruising.


Causes for Bruising

Although everyone is susceptible to bruises, some people are more likely than others to bruise easily. Here are some factors that contribute to bruising:

  • Medication: If you take medicine to prevent blood clotting, you might bruise more easily because the medication will cause more bleeding into your skin or surrounding tissues. Drugs such as aspirin, clopidogrel (Playix) and warfarin (Coumadin) decrease your blood's clotting abilities. So, if you take these drugs, bleeding from a damaged capillary will take longer to stop, and more blood will be able to leak out to form a bruise. Additionally, corticosteroids cause your skin to become thinner, leaving you with less protection for your capillaries. Cortisone medicines such as prednisone make blood vessels very fragile and increase the chances for bruising.
  • Dietary Supplements: If you take supplements such as fish oil or ginkgo, you might be increasing your risk for bruising. These supplements thin your blood, so make sure your health care professional is aware you're taking them, particularly if you're also on a blood thinning medication.
  • Medical conditions: People with blood clotting problems such as hemophilia and liver diseases are at risk for severe bruising.
  • Age: Blood vessels become more fragile as you age, so older people bruise much more easily than younger people. Additionally, as your skin thins with age, your blood vessels will have less protection and cushion from injury. While it might take a lot of force for a kid to bruise, an elderly person might bruise as a result of a mild bump.

Read on to learn how you can treat a bruise and what you can do to prevent bruising.


Bruise Treatment and Prevention

You've just run into a desk at work, and you know you're probably going to get a nasty bruise. What can you do to minimize bruising after an injury?

Although most bruises disappear over time, you can take some steps to speed up the process.


  • First of all, apply a cold compress to the area. If you don't have an icepack readily available, put some ice in a plastic bag, wrap the bag in a towel and place it on the area of injury. The cold will reduce blood flow to the injury and thus will limit the size of the bruise. Additionally, the cold will decrease the inflammation of the area and limit swelling.
  • Secondly, if possible, elevate the injured area to a level above the heart. This will decrease the blood flow to the area and will prevent blood from gathering around the injury.
  • Next, try to rest the area so that the muscles near the injury won't be overworked.
  • Apply pressure to the area with your hand. This will help to reduce bleeding.
  • Finally, if your bruise is causing a lot of pain, take acetaminophen (Tylenol, Excedrin) for pain relief instead of a blood thinning medicine such as aspirin.

But how can you prevent bruising in the first place? Although no one intentionally intends to get a bruise, you can take some measures to reduce your risk. First, teach children how to play safely. While it's hard to avoid childhood bumps and bruises altogether, some tips on how to be careful and be aware of your surroundings could help prevent particularly painful blows. Next, be careful when doing work around the house. For example, have someone spot-check you while climbing on ladders. Finally, be sure to use proper safety equipment when playing sports. Shin guards and elbow and knee pads can protect areas that are prone to bruising during contact sports.


Lots More Information

Related HowStuffWorks Articles

  • "Bruises." Kids' Health.
  • "Bruises." Mayo Clinic. Jan. 8, 2008.
  • "Bruises." National Library of Medicine.
  • Roach, Carol. "With the Price of Steak Today Should We Waste it on a Black Eye?" Associated Content: Health and Wellness. Jan. 25, 2009.
  • Shiel, William C. "Bumps and Bruises." Medicine Net.
  • Vorvick, Linda J. "Bruise." May 2, 2009. National Library of Medicine.
  • "Why does bruised fruit turn brown?" Scientific American. July 21, 1997.