What should you know about left heart failure symptoms?

Left-sided heart failure can cause breathlessness, fatigue, cough and fluid build-up, but symptoms need clinical assessment. Breathlessness may appear during activity, when lying flat or at night. Reduced exercise tolerance, tiredness, a fast or irregular heartbeat and swelling around the ankles can also occur. Symptoms may develop gradually or worsen over a short time.

When the left side of the heart cannot move blood forward effectively, pressure can build in the blood vessels of the lungs. This can contribute to breathlessness and a cough, while reduced circulation can make ordinary activity feel harder. The body may retain fluid, causing weight changes or swollen ankles. Atrial fibrillation and hypertension can affect heart function, but these symptoms can also have other causes, so diagnosis requires a clinical history and examination rather than symptoms alone.

Arrange a GP or chronic disease review if breathlessness, fatigue, ankle swelling, cough or palpitations are new, persistent or getting worse. Bring a list of medicines and note activity tolerance, sleep position, swelling and any sudden change. Take prescribed medicines as directed and do not stop them because you feel better. Ask before using anti-inflammatory pain medicines or supplements, as some can affect fluid balance or interact with treatment.

Call emergency services for severe breathlessness at rest, inability to lie flat because of breathing difficulty, chest pressure, fainting, blue or grey lips, new confusion, or sudden weakness. Seek urgent assessment for a rapidly worsening cough with frothy or blood-stained sputum, or a sudden major increase in swelling. Sit upright while waiting for help and avoid driving yourself if severely unwell.

Ask whether your symptoms could reflect heart failure or another condition, which tests or monitoring are needed, and how to track breathlessness, swelling and weight changes safely. Ask how to take each medicine, what side effects matter, and which changes should prompt same-day or emergency care.