What Causes Blood to Thicken?

Thick blood is caused by a variety of conditions, such as heavy proteins in the blood, too much blood in circulation or a blood clot system imbalance, according to Southeastern Medical Oncology Center. Diseases such as cancer and lupus can also lead to thick blood.

Thick blood moves slower through the circulatory system, which puts excess strain on the heart and increases the individual’s risk for blood clots, according to Mary Ann Bauman, MD, spokeswoman for the American Heart Association. Thicker blood can also lead to inadequate oxygenation to the brain, legs or vital organs. In addition to cancer and lupus, other factors, such as high lipid levels, diabetes and certain medications, may also increase blood thickness, according to Everyday Health. People who smoke or who already have heart health issues, such as high cholesterol or blood clots, are also more likely to have thicker blood.

The same strategies used for general heart health also improve blood viscosity, according to Everyday Health. This includes quitting smoking, reducing dietary fat intake, exercising regularly, losing weight, and managing cholesterol and high blood pressure. Some patients may require the use of certain medications, such as blood thinners, to manage the thickness of their blood.