Heart failure:
early symptoms and warning signs not to ignore

Article written and reviewed by Dr Luca Moretti

Heart failure can begin gradually. The first signs are often shortness of breath that was not present before, unusual fatigue, or the feeling that routine activities, such as walking uphill or climbing stairs, require more effort than usual. Swelling of the ankles and legs, weight gain due to fluid retention, and difficulty breathing when lying down may also occur.
None of these symptoms, taken alone, proves that heart failure is present. They are common in many other conditions as well. However, they become more significant when they are new, persist, worsen over time, or occur together.

Symptoms that deserve particular attention include:

• shortness of breath during exertion or, in more severe forms, even at rest;
• reduced ability to walk, climb stairs, or perform normal activities;
• unusual fatigue and weakness;
• swelling of the ankles, feet, or legs;
• rapid weight gain due to fluid accumulation;
• difficulty breathing when lying down or the need to use more pillows;
• waking at night gasping for air;
• persistent cough or wheezing, especially when associated with other symptoms;
• abdominal swelling, a feeling of fullness, poor appetite, or nausea;
• palpitations, dizziness, or reduced mental clarity in more severe forms.

Heart failure is a clinical syndrome: symptoms must be interpreted together with the clinical examination and diagnostic tests. This guide is intended to help recognize signs that may justify medical assessment, not to make a diagnosis based on symptoms.

Early symptoms: shortness of breath, fatigue, and reduced endurance

One of the most common signs is dyspnea, meaning the sensation of being short of breath. At first, it may occur only during relatively demanding exertion; as the problem progresses, it may appear during increasingly lighter activities. A person may notice, for example, that they have to slow down while walking with others, stop more often on stairs, or take longer to recover after an activity that they previously tolerated well.
Dyspnea is not specific to heart failure: anemia, respiratory diseases, excess weight, physical inactivity, and many other conditions can cause it. What matters most is the change from the person's usual level and its association with other features such as edema, orthopnea, or weight gain.

Fatigue and weakness may also occur early. In heart failure, the heart may be unable to increase cardiac output adequately during exertion, and congestion may contribute to reduced functional capacity. For the patient, the result can be very concrete: grocery shopping, getting dressed, doing household chores, or walking a usual distance becomes more tiring.
These symptoms are nonspecific, however, and should not be interpreted in isolation. New and persistent fatigue, especially when accompanied by shortness of breath or swelling, warrants clinical assessment.

Shortness of breath when lying down and nighttime awakenings

A particularly suggestive symptom is orthopnea: difficulty breathing when lying completely flat, which improves when sitting up or elevating the upper body. Some people report having started to sleep with two or three pillows when they did not do so previously. Another sign is paroxysmal nocturnal dyspnea, meaning sudden awakening after a few hours of sleep with a marked sensation of air hunger that forces the person to sit up or get out of bed.
These symptoms can occur when increased pressures in the left side of the heart promote pulmonary congestion. They are more specific than simple exertional dyspnea, but even they are not sufficient on their own to establish a diagnosis.

A cough that occurs mainly at night or worsens when lying down can accompany congestion. Wheezing is also sometimes reported. If breathing difficulty instead becomes sudden and very severe, especially with sweating, agitation, or pink frothy sputum, the clinical picture may be compatible with cardiogenic pulmonary edema and requires urgent assessment.

Swollen legs, weight gain, and fluid retention

When venous return and filling pressures increase, fluid can accumulate in the tissues. Edema often initially appears at the ankles and legs and is more evident in the evening. In more advanced forms, it can also affect the thighs, abdomen, and other areas.
Edema alone does not identify heart failure: venous insufficiency, some medications, and kidney, liver, or lymphatic diseases can produce similar swelling. Its association with dyspnea, orthopnea, or worsening ability to carry out activities, however, increases suspicion.

Fluid retention can cause weight gain over a few days. Weight does not necessarily increase because the person is accumulating fat: in a patient with known heart failure, a rapid change can mainly reflect retained water and sodium. This is why weight monitoring is often used as part of home follow-up.
More pronounced swelling on only one side, leg pain, or sudden asymmetric swelling instead requires consideration of causes other than heart failure and should be assessed clinically.

Other possible symptoms and why there is no single decisive symptom

Abdominal congestion and reduced perfusion can be associated with a feeling of fullness, poor appetite, nausea, or abdominal swelling. Some patients experience palpitations, dizziness, or difficulty concentrating. In advanced forms, involuntary weight loss may occur instead of weight gain, progressing as far as cardiac cachexia.
The essential point is that heart failure is not diagnosed by counting symptoms. Clinical manifestations have limited sensitivity and specificity and often overlap with lung disease, anemia, obesity, kidney failure, thyroid disorders, and many other conditions.

Clinical examination and tests are therefore needed to confirm or exclude the suspicion. In the modern diagnostic pathway, ECG, blood tests, natriuretic peptides, and above all echocardiography play central roles. The guide on how heart failure is diagnosed explains how these tests are used.

When to contact a physician and when urgent medical attention is needed

New or progressive shortness of breath, a clear reduction in exercise tolerance, persistent edema, or a combination of compatible symptoms warrants medical assessment, especially in the presence of known heart disease, hypertension, previous myocardial infarction, valvular heart disease, cardiomyopathy, diabetes, or kidney disease. Early recognition makes it possible to determine whether the symptoms are caused by the heart or by other conditions and to start appropriate treatment.
People who already have a diagnosis of heart failure should instead pay particular attention to changes from their own stable condition. Increased shortness of breath, swelling, or weight can indicate decompensation: these aspects are addressed in the guide on warning signs of heart failure.

Sudden or very severe breathing difficulty, chest pain, loss of consciousness, severe weakness, marked confusion, or blue or gray discoloration of the lips and skin are signs that may indicate a serious acute condition. In these cases, it is appropriate to call 112 or 118 and not drive yourself to the emergency department.

Frequently asked questions about heart failure symptoms

What are the early symptoms of heart failure?
Common symptoms include shortness of breath during activities that were previously well tolerated, unusual fatigue, reduced ability to walk or climb stairs, swelling of the ankles and legs, and, in some cases, weight gain due to fluid retention.

Do swollen legs always mean heart failure?
No. Leg edema can have many other causes, including venous insufficiency, medications, kidney disease, or liver disease. It becomes more suggestive of heart failure when associated with shortness of breath, rapid weight gain, or reduced exercise tolerance.

Can you have heart failure without swollen legs?
Yes. Some people mainly have shortness of breath, fatigue, or difficulty breathing when lying down and may not have obvious edema, especially in the early stages or during effective diuretic therapy.

Can a nighttime cough be caused by heart failure?
It can, especially if the cough occurs together with shortness of breath, worsens when lying down, or requires sleeping with more pillows. However, cough has many causes and by itself cannot establish a diagnosis of heart failure.

When do heart failure symptoms require urgent assessment?
Sudden or very severe breathing difficulty, chest pain, fainting, severe weakness, altered consciousness, or blue or gray discoloration of the lips and skin require urgent medical attention and may make it necessary to call 112 or 118.