During a blood test, only a small amount of blood is usually taken, so you should not feel ill from the loss of blood. However, occasionally some people feel faint while having their blood taken.
If you feel weak or dizzy while having a blood test, tell the doctor or nurse who is taking the sample as they can help you feel more comfortable.
After a blood test, you may have a small bruised area on your skin where the needle went in. If you develop redness or swelling (inflammation), you may have an infection. See your GP for advice.
Bruising
Occasionally, a larger area of bruising may appear after a blood test. Bruises are the result of bleeding under the skin.
The most common causes of bruising after a blood test are:
- lack of pressure at the site of the jab until the bleeding has stopped
- a vein or other blood vessel being damaged by the needle while it was being inserted
Bruises can be painful but are usually harmless. However, tell your GP if you frequently get bruises after having a blood test.
