Bruising after a blood test (2014)

Key points below

Why does my child have a bruise?

A bruise is caused by blood pooling under the skin.  Sometimes a small bruise will occur when a blood test is done. It may happen at or around the area where the needle was put into your child’s vein. The bruise is temporary and will go away. 

Can a bruise be avoided?

Not every bruise can be avoided.  Putting pressure on the area where the blood was drawn can help prevent a bruise.  Pressure helps stop the flow of blood to the area where the needle was put in.  This may keep the blood from pooling under the skin.

What should I do if a bruise happens?



Call your child’s doctor, nurse, or clinic if you have any questions or concerns or if your child has: 

  • Pain or swelling that is very bad or lasts more than 3 days.
  • A hard time moving the elbow through its normal range of motion.
  • Bruising that gets worse or feels like a hard lump when touched.
  • Special health care needs that were not covered by this information.