A blood clot in a body can lead to some severe complications like:
Heart attack– which happens when the blood flow to the heart tissue is reduced or cut off leading to a possible heart attack.
Brain stroke – when there is a blood clot in the blood vessels of a brain, it interferes with the blood flow which leads to a stroke. If there is a reduced blood flow due to a temporary clot , it can lead to a ministroke or a transient ischemic attack (TIA).
Pulmonary embolism- when a blood clot travels to the lungs and blocks the blood flow, leading to decreased oxygen levels and damage to the tissues of the lung.
A blood clot can even restrict blood flow in the other parts of the body as well leading to severe damage. The other areas that can get affected are:
Limbs
Kidneys
Gastrointestinal tract