What Causes Feet to Swell?

Why Do Feet Swell?

Swollen feet are a common medical condition caused by a wide variety of underlying factors. The basic reason feet swell is that certain conditions cause fluids to congregate in the feet, which makes them puff up. Even in a healthy person, the feet may swell slightly at any given point during the day; since gravity pulls the fluids of the body downward, the feet tend to be somewhat more swollen looking and will likely feel more swollen when one has been on their feet for a long period of time, as opposed to lying down, or lying with the feet elevated, which tends to prevent swelling.

Pregnancy and Hormones

One of the most common causes of excessive swelling in the feet is pregnancy. During pregnancy a woman's body is filled with more blood than usual, which can cause veins to swell or leak blood into the tissues, which leads to swelling, especially in the feet. An imbalance in hormones can also lead to feet swelling. For instance, birth control pills may cause feet swelling in some women.

Injury to the Feet and Ankles

Another cause of foot and ankle swelling is injury or trauma to the feet. When the tissues and muscles of the feet and ankles are strained or damaged, they will become inflamed and fill with blood, causing swelling. A sprained ankle, foot, or broken bone in the foot will usually cause a large amount of swelling, especially in the days immediately following the injury. Walking with bare feet on very rough surfaces can cause the bottoms of the feet to become inflamed and swell. Oftentimes serious injury is also accompanied with purple, blue, black, green or yellowish discoloration from bruising. When swelling is caused by a injury, the incident that caused the swelling is usually easy to discern, and the swelling will be localized in the injured area.

Other Causes

There are are so many conditions that can cause feet swelling, it may sometimes be difficult to determine the cause in a specific case. Some of the more common causes are malnourishment and especially poor intake of carbohydrates and salt, drug abuse, arthritis, inadequate sodium retention, and the excessive use of laxatives. Problems with the kidneys or liver can also lead to swollen feet, such as liver cirrhosis or kidney failure. Swelling in the feet and other parts of the body may also be a result of an allergic reaction.