According to more than 30 trials completed before 1995, very strong evidence suggests that a class of drugs known as angiotensin-converting enzyme (ACE) inhibitors can treat heart failure effectively. The more severe the heart failure, the better the response to ACE inhibitors, and benefit of persistent use may continue over many years. Another class of drug known as beta-blockers can substantially reduce the risk for death regardless of the cause of heart failure. These drugs are safe for patients with advanced heart failure. They also may help patients whose heart failure has not yet caused symptoms. Aldosterone, a chemical secreted by the adrenal glands, may increase both the amount of blood in the body and blood pressure. A type of drug known as aldosterone antagonists can benefit patients with more severe heart failure. ACE inhibitors, beta-blockers, and aldosterone antagonists can protect the heart from further damage and slow the progression of heart failure. They have all been shown to improve survival and reduce hospitalizations. For patients who cannot take ACE inhibitors because of the drug's side effects, another class of drugs known as angiotensin-receptor blockers is a good alternative. Diuretics help patients with heart failure get rid of excess fluid by increasing urine flow. Diuretics can improve symptoms of heart failure but are not suitable as the sole treatment. Digitalis has long been used to control heart failure because it increases the force of the heartbeat, alleviates symptoms, and lessens the need for hospital admission. Nitrates and a drug called hydralazine are suitable for patients with heart failure who also have significant kidney disease.