The symptoms of an embolism are determined by several factors, the most important of which are the blood vessel involved and the size of the embolism. If the embolism is small and in a minor blood vessel, there may be no immediate symptoms at all, whereas a large embolus can totally obstruct blood flow to a vital area and may be life threatening. For example, if a thromboembolism is large enough to totally obstruct an artery, then the tissue supplied by the artery will die. If this occurs in one of the coronary arteries on the surface of the heart, the patient will have a heart attack (myocardial infarction).

A cerebral embolism or, more rarely, a paradoxical embolism could lead to either a transient ischemic attack (TIA) or a stroke, both of which can produce symptoms that are temporary or permanent. The symptoms of a TIA or stroke include the following:

People may also have a variety of visual problems that include the following:

• Partial loss of vision or complete blindness
• Double vision
• Abnormal eye movements
• Blurred vision
• A gray shading or fogging within the field of vision

The signs and symptoms of an arterial embolism depend on the artery that is blocked and the organs or region that it had been supplying. Obstruction of an artery in an extremity usually results in symptoms in that extremity, which include the following:

• Pain
• Numbness
• Coldness
• Tingling
• Lack of pulse in the arteries on the far side of the blockage
• Paleness or mottling (splotches) on the skin
• A heightened sensitivity of the skin (paresthesia)
• Muscular spasm or paralysis

Later, blebs (blisters) and skin necrosis (tissue death) may appear, and gangrene may result.

The symptoms of venous embolism range from local pain, swelling and tenderness to sudden cardiac death.

The greatest risk factor for pulmonary embolism is the presence of deep vein thrombosis, or clots in the veins of the legs and pelvis. These clots may break off, travel through the circulatory system to the lungs, and become lodged, creating a pulmonary embolism. A pulmonary embolism produces symptoms such as the following:

• Chest pain
• Rapid heart beat (tachycardia)
• Feeling faint (dizziness)
• Shortness of breath (dyspnea)
• Rapid breathing
• Cough, sometimes with blood (hemoptysis)
• Rales or crackles (a lung sound heard when listening to the chest)

The symptoms of an amniotic fluid embolism include the following:

• Shortness of breath (dyspnea)
• Dramatic fall in blood pressure
• Rapid progression to cardiac arrest (in which the heart stops beating)

If a leg or arm embolism is not treated promptly, there is a danger that tissues on the far side of the blockage will die and gangrene may develop.

In cases of a fat embolism, which usually occurs approximately 48 hours after a major bone fracture, symptoms include the following:

• Tachycardia
• Rapid breathing
• Restlessness
• Confusion
• Rash
• Sleepiness
• Bluish tint to the skin (cyanosis)

An air embolism is a life-threatening emergency that will lead to the heart’s stopping (cardiac arrest) and sudden cardiac death if not treated immediately. A major cause of air embolisms are rapid ascents during deep-water dives. Symptoms usually appear very quickly after the ascent and may include:

• Dizziness
• Bloody froth from nose or mouth
• Paralysis
• Convulsions

One of the most common symptoms of a cholesterol embolism is blue toe syndrome. This condition is characterized by a bluish tint to the skin (cyanosis) caused by blockage of small blood vessels in the foot by cholesterol crystals.