7 Signs of a Blood Clot and What It Looks and Feels Like

Blood clots can be life-saving when it plugs up a broken blood vessel but it can also be deadly when it forms inside an intact blood vessel. You may have a deadly blood clot forming or flowing through your bloodstream without any symptoms. It is only when this blood clot blocks most of the blood supply to an organ that the symptoms become clearly obvious and may even turn deadly within seconds to minutes.

Read more on deadly blood clots.

How To Spot A Blood Clot

A blood clot is not a problem if it seals a break in a blood vessel and stops bleeding. The problem arises when a blood clot forms inside an intact blood vessel and obstructs the normal blood flow. Every part of the body requires blood to function normally. Therefore a blood clot that limits or blocks blood flow prevents an area from functioning as it should and gives rise to symptoms based on the function of the affected area.

For example, when a blood clot blocks the blood supply to the brain then brain activity is affected. A person may experience numbness, weakness, paralysis, loss of sensation like vision and hearing, dizziness, confusion and even less of consciousness. This is linked to all the functions of the brain. It may be momentary in a transient ischemic attack (TIA) but once the blood supply is cut off then it results in a stroke.

Blood Clots and Blood Vessels

There are two main types of blood clots – a thrombus and an embolus. A thrombus simply refers to a blood clot that is located at the site where it forms. An embolus on the other hand is a blood clot (thrombus) that has dislodged from where it was formed and travels through the bloodstream to lodge elsewhere. An embolus can also refer to other masses traveling in the bloodstream, and not only to a blood clot. Therefore all blood clot emboli (singular ~embolus) start as thrombi (singular ~ thrombus).

Read more on thrombus and embolus.

Blood clots are essentially plugs formed from components of blood like platelets, red blood cells and fibrin. The process of blood clot formation is known as coagulation. Usually it is triggered when there is a break in a blood vessel. The inactive components of coagulation are constantly circulating in the bloodstream but only activated when needed. However, in some cases these components are prematurely activated and a clot forms even within any break in the blood vessel that leads to blood loss.

The type of blood vessel where the blood clot is located also determines the effect and signs that may arise. Arteries carry oxygen-rich blood from the heart throughout the body. Veins drain oxygen-deficient blood from all around the body and return it to the heart. When a clot blocks blood flow in an artery then the affected region will not receive blood rich in oxygen and nutrients. If the clot blocks blood flow in a vein then blood cannot be drained away and becomes backed up a well as seeps into the tissue spaces.

Video: Signs of a Blood Clot

This video on the signs of a blood clot was produced by the Health Hype team.

What Does A Blood Clot Look Like?

A blood clot cannot be seen within the naked eye when it occurs within an intact blood vessel. However, the consequences of the blood clot may be evident as symptoms, as is seen in conditions such as a stroke (blood clot in the brain), heart attack (blood clot in the coronary arteries of the heart), pulmonary embolism (blood clot in the lung), peripheral arterial disease (blood clot in the leg artery) and deep vein thrombosis / DVT (blood artery in the deep veins of the leg).

Paleness and Blue Skin Color

Depending on the area of the body that is affected by a blood clot, there may be visible paleness of the overlying skin. This is more likely to occur when a blood clot blocks an artery which then prevents sufficient oxygen-rich blood from reaching the target area. The red hue of blood is responsible in part for skin color and this color is affected when the blood supply is interrupted. Paleness (pallor) may eventually progress to a bluish tinge (cyanosis) once there is insufficient oxygen flowing through the specific part of the body.

Pain and Numbness

Pain is another sign of a blood clot that is limiting or obstructing the flow of blood. This is due to ischemia – tissue injury that arises with low blood oxygen levels. Initially the pain may only be felt when the affected area needs more oxygen, like when there is increased activity of that area. The pain becomes persistent once the blood flow is entirely obstructed. Eventually there may be numbness once there is death of the affected tissue and disruption of nerve impulses from that area.

Loss of Function

Without sufficient oxygen and nutrients, the affected area will not be able to function as normal. This loss of function is initially partial but eventually there is a complete loss of function when the blood supply is totally blocked for a period of time. Depending on the area which is affected, this loss of function varies as will the symptoms. For example, in muscular areas like the limbs there is muscle weakness. If vital organs like the brain (in a stroke) or heart (in a heart attack) are involved then it can result in death.


Swelling of the affected area is more likely to occur when there is a blood clot in the vein(s) that empty blood from the specific region. Since the vein is obstructed, blood cannot be carried away back to the heart. The pooling of blood causes fluid and eventually even blood to enter into the tissue spaces of the affected area which then results in swelling. This swelling may be more obvious when it occurs in the limbs, as is seen with a swollen leg in deep vein thrombosis (DVT).


C0ldness of an affected area due to a clot interrupting the blood supply is more likely to be noticed in the limbs. Arterial blood not only carries oxygen and nutrients to an area but it also carries heat from the torso. Furthermore the inadequate supply of oxygen and nutrients prevents cells in the affected area from producing sufficient energey and therefore heat. This is most notable at the tips of the limb, namely in the fingers and toes.

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