Swollen Feet and Ankles: Common Causes and When to Worry

Your shoes feel tight by afternoon. Your ankles look puffy. You press a finger into the swollen spot and it leaves a dent that takes a few seconds to fill back in. Doctors call this swelling edema. It happens when fluid builds up in the tissues faster than the body can drain it away (Trayes and colleagues, 2013).

Swelling can come from something as simple as a long day on your feet. It can also be a sign of a problem that needs care. This guide will help you tell the two apart.

What Causes Swollen Feet?

Common causes of swollen feet include long hours of standing or sitting, weak leg veins, an injury, some medicines, and pregnancy. Sometimes swelling points to a blood clot, an infection, or a heart, kidney, or liver problem (Trayes and colleagues, 2013). Two questions narrow it down fast: is it one foot or both, and did it come on slowly or all at once?

Benign Causes of Foot Swelling

Long hours on your feet or in a chair. When your legs hang down for hours, fluid settles into the feet and ankles. This kind of swelling tends to build through the day and go down after a night lying flat, because raising the legs helps it drain (Trayes and colleagues, 2013).

Pregnancy. Swelling of the feet, ankles, and legs is common in pregnancy. In one study, more than half of women said they had it (Ponnapula and Boberg, 2010). But call your prenatal care provider right away if swelling comes with a bad headache or changes in your vision. Those can be early signs of preeclampsia, a serious blood pressure problem in pregnancy (Miller and Vollbracht, 2021).

Musculoskeletal Causes

Injuries. A sprain or a broken bone causes swelling where it's hurt, often with pain and bruising. Doctors use a short checklist, called the Ottawa ankle rules, to decide who needs an X-ray after an ankle or midfoot injury. It very rarely misses a fracture (Bachmann and colleagues, 2003). If you can't put weight on the foot, get it checked. Our ankle sprain guide covers the details.

Stress fractures. A tiny crack in a bone from repeated stress can cause swelling and tenderness. It's worth considering after a sudden jump in activity, or lots of repeated activity with little rest (Patel and colleagues, 2011). Early X-rays can look normal, so a repeat X-ray or an MRI is sometimes needed.

Tendon problems. The posterior tibial tendon runs along the inner ankle and helps hold up the arch. When it's irritated, pain and swelling show up along the inner ankle and arch. It's a common problem that often goes unrecognized (Supple and colleagues, 1992).

Gout. A gout flare brings severe pain, swelling, and tenderness that build fast, often with redness. The big toe joint is the classic spot (Schlesinger, 2007). Our gout guide explains flares and treatment.

Venous and Lymphatic Causes

Weak leg veins (chronic venous insufficiency). Leg veins have one-way valves that help push blood back to the heart. When the valves wear out, fluid pools in the lower legs. Long-lasting swelling in one or both legs often comes from this problem. Brownish staining of the skin around the ankles is a telltale sign of this kind of swelling (Trayes and colleagues, 2013). Good skin care matters, because the skin can break down and form ulcers.

Blood clot (deep vein thrombosis, or DVT). A clot in a deep leg vein commonly causes pain, swelling, and redness in that leg (Kruger and colleagues, 2019). It's diagnosed with a blood test and an ultrasound. Treatment lowers the chance that a piece breaks off and travels to the lungs (Kruger and colleagues, 2019; Freund and colleagues, 2022). That's why one swollen, painful leg needs to be checked right away.

Lymphedema. Lymph vessels drain extra fluid from the tissues. When they can't keep up, swelling builds and tends to get worse over time. You can be born with it, or it can follow cancer treatment, surgery, radiation, or an injury (Grada and Phillips, 2017; Trayes and colleagues, 2013). The skin often feels firm, and pressing it may not leave a dent. Lymphedema is lifelong, but treatment can limit how much it progresses (Grada and Phillips, 2017). Compression garments or pump devices may help (Trayes and colleagues, 2013).

Systemic Causes

Sometimes swelling starts outside the foot. Heart, kidney, liver, and thyroid problems can all cause swelling (Trayes and colleagues, 2013). So can sleep apnea, a breathing problem during sleep (Trayes and colleagues, 2013). Swelling that builds quickly, or shows up in other parts of the body, needs prompt medical care (Trayes and colleagues, 2013).

Medicines. Many drugs can cause swelling, and the link to the drug often goes unrecognized (Largeau and colleagues, 2021). Blood pressure pills called calcium channel blockers, such as amlodipine, are a well-known example. In a large review of trials, ankle swelling was much more common on these drugs than on a dummy pill (placebo). Swelling was also more likely at higher doses (Makani and colleagues, 2011). Steroids, hormones such as estrogen or testosterone, and anti-inflammatory pain relievers such as ibuprofen can also cause swelling (Trayes and colleagues, 2013). Never stop a medicine on your own. Ask the doctor who prescribed it.

One Swollen Foot vs. Both: Why Sidedness Matters

Start by looking at both feet. Swelling in both feet points to something that affects the whole body. Long hours upright, vein problems, medicines, and heart, kidney, or liver problems all fit that pattern (Trayes and colleagues, 2013). Swelling in only one foot, left or right, points to local causes, like an injury, an infection, a flaring joint, or a blood clot.

One-sided swelling deserves a closer look. A red, hot, swollen big toe with no injury is a classic sign of gout (Schlesinger, 2007). A foot that is red, warm, tender, and getting worse can be a skin infection called cellulitis (Raff and Kroshinsky, 2016). Get that checked right away, especially if you have diabetes. And a swollen, painful calf and foot on one side can be a blood clot (Kruger and colleagues, 2019). That is not a wait-and-see problem. Get checked today.

Red Flags: When Swelling Needs Urgent Attention

Some swelling can wait for a regular visit. These signs can't:

• Chest pain, shortness of breath, or fainting with leg swelling. Call 911. These can be signs of a blood clot in the lungs (Freund and colleagues, 2022).
• One leg suddenly swollen and painful, often with redness. Get checked today for a blood clot (Kruger and colleagues, 2019).
• Redness, warmth, and tenderness that keep spreading. That can be a skin infection that needs treatment (Raff and Kroshinsky, 2016).
• Swelling in pregnancy with a bad headache or vision changes. Call your prenatal care provider right away. These can be early signs of preeclampsia (Miller and Vollbracht, 2021).
• Swelling that builds quickly or spreads to other parts of the body. This needs prompt care (Trayes and colleagues, 2013).
• Swelling after an injury when you can't put weight on the foot. You may need an X-ray (Bachmann and colleagues, 2003).

If you have diabetes or numb feet, don't wait on any of these. A sore you can't feel can let infection in, and nerve damage raises the risk of ulcers and amputation (Callaghan and colleagues, 2015).

When to See a Podiatrist

See a doctor for swollen feet if the swelling is in only one foot, came on suddenly, hurts, or comes with redness or warmth. Also get checked if the swelling doesn't go down after a night's rest with your feet up, or if it keeps coming back.

A podiatric evaluation makes sense when swelling:

• Comes with foot or ankle pain
• Follows an injury, especially if walking is hard
• Keeps coming back or won't go away
• Comes with brown staining, a rash, or thick skin around the ankles
• Makes it hard to wear shoes or walk

We examine the foot and ankle, look for injury, tendon, and joint causes, and check your circulation. If the swelling points to a heart, kidney, or other medical cause, we coordinate with your primary care doctor.

Managing Benign Swelling

For swelling in both feet with no pain or warning signs, try these:

• Raise your feet. Swelling from weak veins improves with elevation and gets worse when your legs hang down (Trayes and colleagues, 2013).
• Break up long stretches of sitting or standing, so your legs aren't hanging down for hours.
• Try compression socks, if they're safe for you. People with blocked leg arteries or heart failure shouldn't use compression without a doctor's OK (Andriessen and colleagues, 2017).
• Take care of your skin. Keep it moisturized and watch for cracks or sores, which can turn into ulcers (Trayes and colleagues, 2013).

If swelling keeps coming back, or you see a warning sign, get an exam. Swelling is your body's way of saying something has changed. Finding out what changed is the first step. Call us at (760) 728-4800.