Updated: Apr 23
There are many causes of swelling (oedema) of the feet and ankles. Some of these are more common, as a result of getting older, being on your feet a lot or the effects of hot weather. Some are because of other problems. This post describes the most common causes of swelling of the feet and ankles, and what you should do about it.
A short explainer about the circulation of the body and oedema
Blood is pumped from the heart to all parts of the body via the arteries and it comes back to the heart via the veins. Some fluid from the blood seeps into the tissues of the body, which is a normal process. The fluid then comes back into the veins and also the lymph vessels (which are quite similar to veins), and all of this goes back into your circulation. If more fluid remains in the tissues than is normally the case, that causes swelling.
Blood is actively pumped around the body by the heart, but it comes back to the heart by passively flowing (in other words, it is not pumped back to the heart, only away from the heart). This process is helped by a series of one-way valves in the veins, which help the blood to keep moving towards the heart.
One of the disadvantages of walking and standing on two feet is that gravity works against us, and so it is easier for the blood to pool in our feet and legs, which can make swelling more likely.
Some swelling (as in the swelling that occurs around an injury site) is a normal response of the body when it is trying to repair something.
Causes of swollen ankles
It's not uncommon to get a little bit of swelling around your feet and ankles now and then, especially if you have been sitting or standing for long periods. It is a good idea to get up and move around regularly to get your circulation going. If the swelling is getting worse over time or taking longer to settle once you stop doing whatever caused it, then it could be due to other reasons.
When you are hot, your blood vessels dilate (get bigger) as part of the process of trying to cool yourself, and some fluid seeps from the vessels into the surrounding tissues. If your circulation isn't as good as it could be, it may take longer for the fluid to get back into the circulation, which can cause swelling.
Sometimes the efficiency of your circulation gets worse with age. This can result in pooling of blood and swelling in the feet and ankles. Venous insufficiency means that the veins are not working as well as they should. Chronic (long-term) venous insufficiency also leads to changes in the skin, and sometimes infections and ulcerations.
The menstrual cycle
Some women get swelling in their feet and ankles as a normal part of their menstrual cycle.
It is not uncommon to get swollen ankles and feet during pregnancy, especially as the baby gets bigger. This is because of increased pressure on the veins that come back up from the legs into the body, behind where the baby is.
Sudden or severe increases in foot and ankle swelling during pregnancy needs an immediate medical assessment, as it can be a sign of preeclampsia. This needs to be treated promptly.
When you injure your foot or ankle (for example, when you sprain your ankle), you can get swelling in the short term from bleeding in the area, but also afterwards, as your body tries to repair the damage caused by the injury.
When you have an infection the body causes an inflammatory reaction to fight off the infection and repair any damage. This can include swelling, redness, heat and discomfort. If you have spreading inflammation, red lines going up your legs, tenderness in the back of your knee or groin, then seek medical advice immediately.
Blood clot (deep vein thrombosis, or DVT)
Blood clots in the legs can occur after prolonged periods of sitting (especially in aeroplanes), after surgery or sometime for no obvious reason at all. A DVT can cause swelling in the leg (but not always). Other signs can include discomfort or a sense of heaviness in the back of the calf and veins under the skin which are more noticeable on one leg than the other. If you suspect that you have a DVT then you should see a doctor immediately. A DVT can be quickly diagnosed with an ultrasound scan of the legs.
As a result of other medical problems
Heart, liver and kidney disease can all cause swelling as a side effect. Consult your doctor for further information and assistance if this applies to you.
Side effects of medications
Lots of medicines can cause swelling of the feet and ankles as a possible side effect. The amount of swelling as a side effect can vary from person to person. Some examples include:
Some blood pressure drugs (calcium channel blockers)
Some antidepressants (tricyclics and monoamine oxidase inhibitors)
Non-steroidal anti-inflammatory drugs
Some drugs used to treat diabetes
Some hormones (for example, oestrogen and testosterone)
If you notice swelling as a side effect, do not stop taking the medication abruptly, but seek medical advice as soon as possible.
Lymphoedema refers to swelling that is caused by problems with the lymphatic system, either the lymphatic vessels themselves or the lymph nodes which are part of the lymphatic system. There are two broad categories of lymphoedema:
Primary lymphoedema, which occurs from a problem with the lymphatic system itself. This can happen at any age and is often hereditary.
Secondary lymphoedema, which occurs from injury to the lymphatic system from another cause. A common example is oedema that occurs after lymph nodes have been removed during surgery.
Swelling of one ankle (or foot or leg)
Sometimes it is obvious why one side is swollen and the other is not. For example, an ankle sprain or foot infection is likely to produce swelling on one side only. If you have a foot, ankle or leg swelling on one side only for no obvious reason, then you should see your doctor for further evaluation.
How can I reduce the swelling in my feet and ankles?
If there is a medical cause for your swelling then your doctor will advise you on ways to help with this. For example, you may be prescribed a type of medicine called a diuretic, which helps to get rid of extra fluid. Swelling from any cause may be helped by one or more of the following:
Other more specialised equipment, such as an intermittent pneumatic compression pump
Swelling as a result of injury
There are two approaches requires when you have an injury which causes swelling, and these differ according to how recently the injury occurred.
Right after the injury, you want to minimise swelling that will make it worse (such as from bleeding around the injury site).
Later on, when you are trying to help it get better.
Right after an injury, then the following four steps are recommended:
Rest Exactly what it says. Stop using the injured area and rest it
Ice You can put an ice pack over the affected area. Protect your skin from getting an ice burn by putting something between the ice pack and your skin. A towel, for example.
Compression Use an elasticated bandage or similar to exert some gentle compression to the area. Be careful not to use too much compression, which can cut off the circulation. Make sure that you can see your toes and that when you squeeze them, they get pale and return to being pink when you let them go. If they go a purple or dusky colour, then the compression is too tight.
Elevation If you lie down and elevate your foot and leg so it is higher than your heart, then you have gravity working in your favour, which will help the limb to drain and not swell so much.
Later on, when you are rehabilitating from the injury there are individual approaches, depending on the type of injury. You should consult us for further information and a plan customised to your needs.
When should I see a health professional?
You should consult a doctor immediately if any of the following apply:
Sudden or severe swelling of feet (or hands)
Spreading inflammation of the area (warmth and redness, heat and pain)
Swelling of one foot/ankle for no obvious reason
Swelling that is accompanied by other symptoms, such as fever, shortness of breath or chest pain
Apart from that, seek advice for any swelling which is not mild and does not go away by itself. Our team can help to assess the cause and provide a treatment plan that is customised to your needs.