A swollen foot may be caused blood vessel blockage, lymphatic blockage, or trauma from an injury. Other causes of swelling in one foot include skin infections like cellulitis, or ankle arthritis which can also be the cause of one swollen ankle. Read below for more causes, related symptoms, and treatment options for a swollen foot.
One swollen foot explained
Swelling of one foot can be a concerning symptom as it can likely interfere with everyday activities. It can be caused by a variety of ailments affecting the foot, including trauma or venous blockage such as by a blood clot. Fluid backup can also be caused by physical obstruction, such as a mass, in the surrounding area. It is important to seek care if you have swelling of only one foot with no apparent cause.
Common characteristics of swelling of one foot
If you're experiencing swelling of one foot, it can likely be described by:
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What causes swelling in the feet?
Swelling of one foot may be caused by a blockage of blood vessels, a blockage in the lymphatic system, or trauma.
Blood vessel blockage
Blood can build up in a single leg, causing swelling of the foot. Blood flows into the leg through arterial circulation and out of the leg through venous circulation. Blockage of either type of blood vessel will cause swelling. Blocked veins cause blood to pool in the foot or leg and blocked arteries will cause severe tissue damage and mild swelling.
- Venous thrombosis: This refers to a clot in the blood vessels that return blood to the heart after it has traveled to the tissues. Venous thrombi (or clots) usually only affect one leg at a time and are formed when there is damage to a blood vessel causing turbulent flow (e.g. not direct flow to the heart). Additionally, individuals with cancer may be predisposed to form clots as a side effect of their malignancy. Surgery and a sedentary lifestyle or a long period of sitting (e.g. plane or car rides) may also predispose an individual to form a clot. If clots are not treated properly, they can travel to the lungs and lead to death.
- Peripheral artery disease: This is a disease in which the arteries that provide blood flow to the lower legs are gradually closed off by cholesterol or fats over time. Without proper blood flow, the leg may become cold and die, necessitating amputation (e.g. surgical removal). When peripheral artery disease causes blockage of the artery, the leg will become severely painful for a short period of time and then it will become cold compared to the opposite leg. If you suspect that you may have lost blood flow to your leg it is important to seek medical care immediately.
- Compartment syndrome: This occurs when swelling of the muscle stops the flow of blood to the lower leg. Unlike peripheral artery disease, this can occur without any arterial blockage and is known to occur in young athletes, especially after long periods of physical exertion. Soccer players and long-distance runners may experience severe swelling of the muscles of their lower legs after a long period of intense running followed by severe pain and then numbness. The treatment for compartment syndrome is to decompress the leg with an emergent surgery known as a fasciotomy.
A lymphatic blockage, also known as lymphedema, is a chronic condition that can be caused by surgery that blocks the vessels that allow lymph to flow out of the legs (e.g. lymphatic vessels).
- Surgery: Surgery for anywhere in the body requires a surgeon to separate or even destroy structures to gain access to the area that needs to be operated on. Surgery on the leg, abdomen, or pelvis can destroy or injure lymphatic vessels that are necessary to drain lymphatic fluid from the body. In some cases, removal or destruction of the lymphatic system is the goal. In surgery to remove cancers in the pelvis, a certain number of lymph nodes will be removed to ensure that cancer has not spread or to control any potential spread. Without those lymphatic structures, it can be difficult to drain lymphatic fluid from the body and lymphedema can result. Over time, lymphedema can cause hardening of the skin and a "woody" texture to the leg or affected foot.
- Radiation treatment: Used for cancer, radiation can also damage many of the different lymphatic vessels and cause lymphedema. Radiation of the legs or pelvis for bladder, gynecological, or lower abdominal cancer can cause scars that restrict the flow of lymphatic fluid throughout the body and lead to lymphedema of the lower legs. There is no effective way to repair the lymphatic system if the damage spreads throughout the affected body part (e.g. leg, abdomen). However, physical activity can help move lymph and slow the progression of lymphedema.
- Infection: Short-term infections do not cause lymphedema; however, long-term infections can. Infections that exist at a lower (e.g. subacute) level or that tend to exist within the lymphatic system can cause lymphedema if not treated in an expedient manner. Mycobacterium is a class of bacteria that is slow-growing and causes tuberculosis and leprosy among other infections. If left untreated, it can damage the lymphatic system and cause lymphedema.
- Cancer: As it spreads throughout the body, cancer can damage the lymphatic vessels and lymph nodes and lead to incurable lymphedema. Even if the cancer is successfully treated, the effects of the damage to the lymphatic system may be irreversible and the leg may be swollen permanently.
Trauma may cause swelling of a foot or leg in the short-term. A sprain, fracture, or bruise can cause swelling of the entire foot for hours or even a day or so after the injury.
- Sprain: A sprain involves anything from a partial tear to a complete tear of a ligament (e.g. a cord of connective tissue connecting muscle and bone). The severity of the sprain does not predict the severity of the lower leg or foot swelling. Your entire foot may be swollen and unable to bear weight for a mild sprain and you may have minimal swelling for a complete tear. Often a physical exam, X-rays, and whether or not you regain the ability to move your foot or extremity quickly determine the severity of the sprain. In all cases, rest, ice, compression, and elevation help decrease swelling and pain and you should seek medical evaluation.
- Fracture: A mild fracture appears similar to a sprain. Swelling, inability to bear weight on the foot or move the foot are common symptoms. However, more severe fractures may result in obviously deformed or misaligned bones or joints. In those cases, it is important that the foot is reset in the proper position either in the emergency department or more commonly through a surgical procedure in which bones are fixed to each other to promote proper healing.
This list does not constitute medical advice and may not accurately represent what you have.
A foot sprain is damage to ligaments within the foot. The term "sprain" refers to overstretching or tearing of ligaments — the strong, fibrous bands of tissue that hold the bones together within the joints. Foot sprains are usually sports or dance injuries. Any sort of running movement that involves sud...
Skin infection of the foot
An infection of the skin of the foot is almost always either fungal or bacterial. A fungal infection of the foot is called tinea pedis, or athlete's foot. It is caused by different types of dermatophyte fungus and is commonly found in damp places such as showers or locker room floors. A bacterial infection anywhere on the skin is called cellulitis if it extends under the skin. It can develop after a break in the skin allows bacteria to enter and begin growing. These bacteria are most often either Streptococcus or Staphylococcus, which are found throughout the environment.
Most susceptible are diabetic patients, since high blood sugar interferes with healing and wounds can easily become chronic and/or deeply infected. Diagnosis is made through physical examination by a medical provider.
Treatment for either a fungal or bacterial infection involves keeping the skin dry and clean at all times. A fungal infection is treated with topical and/or oral antifungal medications, while a bacterial infection will be treated with topical and/or antibiotic medications.
Top Symptoms: fever, foot pain, foot redness, warm red foot swelling, swollen ankle
Symptoms that always occur with skin infection of the foot: foot redness, foot pain, area of skin redness
Urgency: Primary care doctor
Broken foot (navicular bone fracture)
The navicular is one of the bones of the foot.
Top Symptoms: difficulty walking, constant foot pain, pain in one foot, recent ankle injury, foot pain from overuse
Symptoms that always occur with broken foot (navicular bone fracture): pain in one foot, constant foot pain, recent ankle injury
Urgency: In-person visit
An ankle fracture is a break in 1 or more ankle bones.
Top Symptoms: difficulty walking, constant ankle pain, swollen ankle, pain in one ankle, ankle pain from an injury
Symptoms that always occur with broken ankle: pain in one ankle, swollen ankle, ankle pain from an injury, constant ankle pain
Urgency: Hospital emergency room
Arthritis simply means inflammation of the joints. Because the feet and ankles have many small joints and carry the weight of the body, they are often the first place that arthritis appears.
Arthritis is caused by a breakdown in the protective cartilage at the end of each joint, so that the bones begin to wear against each other and the joint becomes stiff and painful. This breakdown may be due to simple wear and tear; an injury; or from rheumatoid arthritis, an autoimmune condition which causes the body to break down its own cartilage.
Symptoms include swelling, warmth, and redness in the joint, and pain with movement or with pressure on the joint.
Diagnosis is made through patient history, physical examination, and imaging such as x-rays, CT scan, or MRI.
There is no cure for arthritis, but treatment is important because the symptoms can be managed to prevent further damage, ease pain, and improve quality of life. Treatment involves physical therapy, pain-relieving medications, and sometimes surgery to help repair damaged joints.
Top Symptoms: swollen ankle, swollen foot, joint stiffness, pain in one ankle, ankle stiffness
Gout is a form of arthritis that causes sudden pain, stiffness, and swelling in a joint. The big toe is often affected.
Top Symptoms: swollen toes
Urgency: Primary care doctor
Septic arthritis is also called infectious arthritis. "Arthritis" simply means inflammation of a joint. In septic arthritis, the inflammation is caused by a bacterial, viral, or fungal infection. The most common is Staphylococcus aureus or staph. These agents reach the joints either from ...
Arthritis is a general term for multiple conditions that cause painful inflammation and stiffness throughout the body. Rheumatoid arthritis (RA) is a chronic condition that is autoimmune in nature, meaning that the body's immune system which normally protects the body by att..
Deep vein thrombosis
Deep vein thrombosis (DVT) is a blood clot that forms in a vein deep in the body. Most deep vein clots occur in the lower leg or thigh.
Top Symptoms: fever, thigh pain, upper leg swelling, calf pain, butt pain
Urgency: Hospital emergency room
Nail infection (paronychia)
Paronychia is an infection of the skin of the fingers or toes, at the place where the skin folds down to meet the nail.
Acute, or sudden onset, paronychia is caused by the staphylococcus bacteria. The organism can gain entry if the nail is cracked, broken, bitten, or trimmed too closely.
Chronic, or ongoing, paronychia is caused by a fungus. Anyone whose work requires their hands to be wet much of the time is susceptible.
People with diabetes or a weakened immune system are more susceptible to nail infections.
Symptoms include sore, reddened, swollen skin around the nail, sometimes with pus collecting under the skin.
Diagnosis is made through physical examination and sometimes skin culture to identify the organism involved.
Treatment for acute paronychia involves having a medical provider clean the wounded nail and drain any infection, and sometimes provide a course of antibiotics.
Treatment for the chronic form involves keeping the skin dry and using an antifungal medication on the affected nail.
Top Symptoms: spontaneous finger pain, fingernail pain, fingernail swelling
Urgency: Phone call or in-person visit
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How to treat swelling in one foot or ankle
Treatment of foot or lower leg swelling is determined by the cause of the swelling. In cases of infection with an abscess, drainage of the abscess and antibiotics may be necessary. In the case of occluded blood vessels, the vessels may need to be opened up either through surgery or medications that dissolve the clot, and in cases of trauma, the bone or ligament may need time to heal.
Blocked blood vessels
A blood vessel that has been blocked by arteriosclerosis or a clot has to be opened up before the tissue suffocates and dies. The following may take place once you seek care in a hospital.
- The clot may be dissolved, ensuring that it does not travel to your lungs
- The blood vessel may be opened or bypassed: Or a limb that has died may need to be removed
- Fasciotomy: A fasciotomy may be completed to alleviate pressure from compartment syndrome.
Sprain or fracture
A sprain or fracture that is mild can be treated at home, but if the pain is too intense or recovery does not occur within a week, medical treatment should be pursued.
- Mild sprains: These should be treated with rest, ice, compression, and elevation as well as anti-inflammatory pain medications (NSAIDs).
- Severe sprains or fractures: These should be evaluated by a medical professional and may need to be placed in some sort of brace to heal or may require surgery to realign the bones.
Lymphedema usually has no treatment, but can be managed successfully through exercise and compression garments.
When swelling of one foot is an emergency
You should seek help without delay if:
FAQs about swelling of one foot
What causes swelling in one foot?
Swelling in one foot is caused by fluid buildup in the foot. Fluid accumulation can take place through many mechanisms. The most common is inflammation following an infection or trauma to the tissues of the foot. When an infection in the foot occurs, the blood vessels of the foot dilate so that white blood cells and other immune cells can access the infected material. When trauma such as a sprain or fracture occurs, the tissues of the foot swell and become inflamed to clean up any blood from bruising and to make the foot sensitive or painful so that it is not used excessively in order to allow time for it to heal.
When is swelling in one foot dangerous?
Swelling in one foot is common, and by itself, it may not need evaluation. However, it should be evaluated urgently by a medical professional for a few reasons: if your foot has become cold in comparison to its partner, you have lost feeling, or you are unable to move your foot. You may have damage to the blood vessels that supply your foot or damage to the nerves that allow you to sense or move your foot. Damage to blood vessels can lead to tissue death and necessitate amputation whereas damage to the nerves in the foot can lead to a permanent inability to use the foot. In both cases, it is necessary to seek evaluation to preserve function and to possibly avoid life-threatening consequences of damage to the foot. Finally, swelling in the foot should be evaluated urgently in the setting of an inability to catch one's breath or pain in the calf as these may be signs of a clot in the leg.
When is foot swelling a sign of an infection?
Foot swelling is most commonly a sign of infection if it is accompanied by a rash or redness along the area where the foot is tender and if there is evidence of fever, chills, or pus emanating from a wound. In some people, these rashes can be signs of cellulitis or erysipelas which are both infections of the skin (albeit by different organisms). A wound that refuses to heal and produces pus or an abscess (a swollen, seemingly fluid-filled sac) are both signs of infection with bacteria that commonly cause skin infections. Often times, rashes or abscesses require medical treatment or drainage to begin healing.
How long does foot swelling from sprain take to disappear?
Foot swelling from a sprain can take variable amounts of time to disappear and can be affected by the degree of injury to the ligament and the treatments that are employed to help the ligament heal. Generally, minor sprains can be treated with the following: by resting and not bearing weight or even using crutches, using cryotherapy or chilling the ankle with ice, using compression or an elastic bandage early to minimize swelling, and elevating or raising the leg above the heart to limit swelling. Over-the-counter painkillers or non-steroidal anti-inflammatory drugs can limit both swelling and pain. Ankle splints can also keep the ankle from being injured as weight-bearing is slowly increased. It may take six to eight weeks to return to full capability following an injury with good care.
How should I treat foot swelling from a blow to the foot?
Swelling from a blow to the foot can usually be treated with at-home treatments described through the acronym R.I.C.E. "R" stands for rest which means that you should avoid placing weight on the foot. "I" stands for ice or cold, meaning the ankle should be chilled both to reduce swelling and to reduce pain. "C" stands for compression which also helps keep fluids from building up within the ankle. "E" stands for elevation specifically above the heart which reduces the ability of blood to pool in the limb. NSAIDs or non-steroidal anti-inflammatory medications are used to decrease swelling in the ankle. Once pain begins to increase, it is very important to resume activity and stretch the ankle as it will allow. Splints and braces are also very useful to stabilize the ankle and increase the ability to gradually increase strain on the ankle. Surgery for severe sprains may help improve the eventual ability of the ankle to bear weight.
Questions your doctor may ask about swelling of one foot
- Where exactly is your foot swelling?
- What is your body mass?
- Do you have a history of high cholesterol?
- Have you ever been diagnosed with diabetes?
Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.
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