Bruises Ngā marū

A bruise is a collection of blood under the skin. They happen if you get a soft tissue injury. A bruise often comes with a lump, which is swelling caused by fluid under the skin.

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Causes of bruises

Bruises happen when there is a break in a blood vessel under your skin. They are most often caused by a:

  • knock or bang to part of your body
  • strain or sprain.

But bruising can also happen because of more serious injuries such a broken bone or internal bleeding.

If there is a large pool of blood collecting under your skin, this is called a haematoma. These are sometimes deeper within your body and may not be noticeable in your skin.

Some people bruise more easily than others. This includes people who:

  • have whānau members who bruise easily
  • take medications to thin blood or stop clotting, such as aspirin or blood thinners
  • regularly take nonsteroidal anti-inflammatory drugs (NSAIDs) for pain relief, including ibuprofen or naproxen
  • have cancer or liver disease
  • have a bleeding disorder such as haemophilia or another blood clotting condition
  • have a deficiency in vitamin C or vitamin K
  • are older and have fragile skin and less protective fat.

Symptoms of bruises

A bruise may not appear straight away, but develop 1 to 2 days after an injury. The area can be painful or tender and it may be swollen.

Bruises look like a mark on your skin and might be blue or purplish in colour. As they heal, they often become yellowish green in colour.

Self care for bruises

Most bruises do not need any treatment and will fade away over 1 to 2 weeks.

If you have a bad bruise, or think you may develop one, you can:

  • keep the area raised to prevent swelling and to relieve pain
  • apply an ice pack for the first 1 to 2 days, several times throughout the day — wrap the ice pack in a towel and do not apply it for more than 15 minutes
  • take paracetamol — check with your healthcare provider before using ibuprofen or other anti-inflammatory medicines.

You can buy creams from a pharmacy that may help speed up the healing of a bruise.

When to get treatment for a bruise

Some bruises can be serious. Seek medical help if:

  • you are on a blood-thinning medicine such as warfarin, dabigatran or rivaroxaban
  • the bruised area becomes very swollen or very painful
  • you cannot move the injured body part.

You should also tell your healthcare provider if you :

  • bruise often for no known reason
  • bruise suddenly with no obvious cause
  • bruise easily
  • you have a family history of bleeding disorders.

You may have an underlying problem that needs medical treatment.