The NHS has warned people to watch for a troubling symptom in the legs that could indicate a potentially deadly medical condition.

According to the health service, swelling in the legs serves as a warning sign of heart failure.

This condition, referred to as oedema, can affect the feet and ankles, leading to discomfort while walking. According to the NHS, symptoms might ease during the morning and “worsen later in the day”.

Heart failure develops when the heart cannot effectively pump blood throughout the body, reports the Mirror.

This typically occurs because the heart has become excessively weak or rigid.

The NHS clarifies: “Heart failure is a chronic condition that generally deteriorates over time. Although it usually cannot be cured, the symptoms can often be managed for many years.”

Experts from Medical News Today indicate that heart failure results in increased blood pressure in the blood vessels because the heart cannot pump blood effectively.

“This elevation in pressure forces fluid out of the blood vessels and into the surrounding tissues, resulting in swelling, or oedema,” they said.

Oedema may look like:

• Swollen or puffy ankles, feet or legs
• Shiny or stretched skin
• Changes in skin colour, discomfort, stiffness and dents when you press on the skin

It can also be caused by:

• Standing or sitting in the same position for too long
• Eating too much salty food
• Being overweight
• Being pregnant
• Taking certain medicines – such as some blood pressure medicines, contraceptive pills, Hormone therapy, antidepressants or steroids
• An injury – such as a strain or sprain
• An insect bite or sting
• Problems with your kidneys or liver
• A blood clot
• An infection

Additional indicators of heart failure include:

• Breathlessness – this may occur after activity or at rest; it may be worse when you’re lying down, and you may wake up at night needing to catch your breath
• Fatigue – you may feel tired most of the time and find exercise exhausting
• Feeling lightheaded and fainting
• A persistent cough, which may be worse at night
• Wheezing
• A bloated tummy
• Loss of appetite
• Weight gain or weight loss
• Confusion
• A fast heart rate
• A pounding, fluttering or irregular heartbeat (palpitations)

Certain individuals with heart failure may also encounter feelings of depression and anxiety.

The NHS adds: “See your GP if you experience persistent or gradually worsening symptoms of heart failure.

“Dial 999 for an ambulance or proceed to your closest accident and emergency (A&E) department immediately if you experience sudden or severe symptoms.”