Swelling in the feet and ankles is a very common symptom and can have a variety of causes. One way that doctors pinpoint the cause of swelling is by noting whether it is occurring in one limb, or in both equally. In many cases, the cause of swelling is something that requires medical attention, such as an infection or injury. If swelling has a sudden onset, medical attention should always be sought immediately.
Some of the most common conditions that can cause foot or ankle swelling include:
- Trauma: The most common foot and ankle injuries that cause swelling include ankle sprains, torn tendons, and fractures. Chronic stress or overuse can lead to tendonitis, bursitis, and ligament or muscle strains, all potential causes of swelling. These are conditions that are more likely to occur with athletic activity or any recent increases in activity, such as walking or running on new terrain.
- Arthritis: Arthritis, or joint inflammation, can cause localized swelling in the foot or ankle. Osteoarthritis is a common form of arthritis that may cause occasional swelling, usually in a single joint. Gout is another form of arthritis that typically causes a very painful, red, swollen big toe joint. Gout can also affect the ankle. Some autoimmune diseases cause swelling and arthritis that affect both feet equally, such as rheumatoid arthritis, psoriatic arthritis, lupus, and reactive arthritis (Reiter's syndrome).
- Vein Problems:
Problems with leg veins often cause swelling in the lower limbs. Veins return deoxygenated blood back to the heart, and as we age they may become damaged, which results in swelling in the legs and ankles. This is known as venous insufficiency, and the most common signs are: one limb that periodically swells (although both can be affected), varicose or spider veins on the leg or ankle, and a brown skin discoloration that can develop over time.
Pain and swelling in the lower leg can also be signs of a blood clot, also known as a deep vein thrombosis (DVT), which can lead to life-threatening complications and requires immediate medical attention. Conditions that create leg immobility can put a person at risk for a DVT- such as air travel, a leg cast, or illness requiring bed rest. Other risk factors include obesity, smoking, pregnancy, use of birth control medications, and inherited blot clotting disorders. If you are a woman taking birth control medications, your risk of DVT is further increased if you also smoke or have an inherited blood clotting disorder known as Factor V Leiden.
- Infection: Skin infection is a common cause of swelling and is usually accompanied by pain and redness. Swelling is often seen with infected ingrown toenails (onychocryptosis), infections between toes, and severe forms of athlete's foot. Other ways infection can occur in the feet include trauma, such as puncture wounds or nail injuries and through diabetic wounds. Although much less common, infection can occur in joints even without direct trauma.
- Medical Conditions: Medical conditions known to cause swelling that affects both legs equally include heart disease, kidney disease, liver disease, and chronic sleep apnea, and complications of diabetes. Premenstrual syndrome (PMS) is also a well-known cause of swelling in the ankles and feet.
- Medications: Some prescription medications can cause swelling that affects both legs equally. They include birth control pills or estrogen replacement drugs, testosterone drugs, corticosteroids and other anti-inflammatory drugs such as NSAIDS, certain blood pressure medicines, and the diabetes drugs Avandia and Actos. Alcohol can also cause swelling in both ankles or feet.
- Pregnancy: Swelling in both ankles and feet during pregnancy is a common occurrence and is caused by a combination of pregnancy hormones, the increased volume of fluid being carried in the blood vessels, and by the growing uterus, which places pressure on the veins that carry blood up from the legs. Swelling in the legs can occur after giving birth as well, and can last a few days after the birth. Swelling during pregnancy should be discussed with your doctor or midwife. Any sudden onset of swelling requires immediate medical attention, as it could signify preecclampsia.
John W. Ely, MD, MSPH; Jerome A. Osheroff, MD; M. Lee Chambliss, MD, MSPH; Mark H. Ebell, MD, MS. Approach to Leg Edema of Unclear Etiology. Journal of the American Board of Family Medicine. 2006;19(2):148-160. Medscape Today News. Accessed 1/20/12.