Acute pericarditis is often accompanied by a constant chest pain emanating from the center of the chest beneath the breastbone (sternum). The pain is caused by the inflamed pericardium rubbing against the heart. It may be sharp and stabbing (pleuritis), or radiate to the neck, shoulder, back or abdomen. The pain may be increased with deep breathing, lying flat, coughing or swallowing. Other symptoms may include:

Signs that may be detected by a physician include a rapid pulse or a pulse that is very weak at the end of each deep inhalation (paradoxical pulse). The patient may also show a tendency to lean forward to avoid or relieve the pain. Severe cases may be accompanied by fluid buildup in the space between the lungs and chest wall (pleural effusion). Constrictive pericarditis may also lead to a swelling of the lower extremities or abdomen, as well as bulging (distention) of the neck veins.