Swollen foot: what are the reasons?

Most commonly, we observe a similar swelling of both feet that can interfere with daily life. There are quite a number of reasons that can explain this:

• Sedentary Lifestyle : Most commonly, foot oedema is due to a lack of physical activity. When one remains seated or in a static position for extended periods, blood and lymph tend to accumulate in the lower limbs of the body. Conversely, when the leg muscles are active, they contract and relax, acting like a pump that pushes fluids towards the heart, thereby reducing the risk of swelling.

• Obesity : Similarly, obesity can cause or contribute to the swelling of the feet. The veins in the lower limbs, whose role is to transport blood back to the heart, are no longer as efficient due to the additional weight exerted on them from the abdomen.

• Hormonal fluctuations : Hormonal changes during the pregnancy or throughout the menstrual cycle can also be responsible for oedema in the feet. Indeed, oestrogen, a hormone whose synthesis significantly increases during pregnancy and whose quantity varies throughout the menstrual cycle, acts primarily by binding to nuclear receptors ER-α and ER-β. In doing so, it triggers a cascade of reactions involving the intensification of the production of intracellular cyclic adenosine monophosphate (cAMP). This, in turn, plays a role in the regulation of the synthesis of nitric oxide (NO), a vasodilator.

• An Endocrine System Disorder : An overactive or underactive thyroid gland can cause swelling or thickening of the skin around the shins and ankles, often hard and waxy in appearance. As a reminder, this organ located in the neck produces the thyroid hormones thyroxine and triiodothyronine, which play a role in regulating calcium metabolism. Found in the blood, calcium is necessary for the proper functioning of the circulatory system.

• Cushing's Syndrome : This disease, in which the adrenal gland produces an excess of steroid hormones, can be responsible for swelling in both feet. Besides this swelling, patients with Cushing's Syndrome typically exhibit other characteristics of the condition, such as changes in skin texture, a roundness of the face, and the appearance of a hump of tissue at the back of the neck.

• Heart Failure : When the heart is weakened, it fails to pump enough blood. This causes the blood to backflow into the veins, leading to an increase in pressure that pushes fluid into the tissues. The blood then tends to pool in the lower limbs, particularly in the feet, resulting in oedema. In addition to swelling, patients suffering from heart failure typically experience rapid shortness of breath during exertion.

• The intake of certain medications : Medications are another common cause of swelling in the feet and legs. This discomfort can particularly be observed with calcium inhibitors, such as amlodipine or nifedipine, non-steroidal anti-inflammatory drugs (NSAIDs), like ibuprofen or naproxen, gabapentin, oral contraceptives, prednisone or with medications fighting against diabetes of the thiazolidinediones type.

• Heat : It is more common to observe swelling of the feet during the summer period. Indeed, when it is hot, the blood vessels dilate to help dissipate body heat, which increases blood flow to the extremities and results in an accumulation of blood and fluids in the feet and ankles. This vasodilation, although necessary for the regulation of body temperature, directly contributes to the swelling of the feet. Moreover, high temperatures increase the permeability of the capillaries, allowing more fluids to escape from the blood vessels into the surrounding tissues.

• The wearing of narrow shoes : By exerting constant pressure on the feet, narrow shoes can cause local inflammation, resulting in swelling of this part of the body. Moreover, ill-fitting shoes can compress the feet and toes, thereby limiting the blood flow to and from the feet. This compression of the blood vessels hinders normal circulation, which can lead to an accumulation of blood and fluids in the feet, exacerbating the swelling.