Beta blockers reduce blood pressure. Beta blockers work by blocking the effects of the hormone epinephrine, also known as adrenaline. As a result, the heart beats more slowly and with less force, thereby reducing blood pressure. Beta blockers also help blood vessels relax and open up to improve blood flow.

Some beta blockers mainly affect your heart, while others affect both your heart and your blood vessels. Which one is best for you depends on your health and the condition being treated.

Beta blockers are also known as beta-adrenergic blocking agents.

Examples of beta blockers include:

• Atenolol (Tenormin)
• Metoprolol (Lopressor, Toprol-XL)
• Propranolol (Inderal, Inderal LA)

Doctors prescribe beta blockers to prevent, treat or improve symptoms in a variety of conditions, such as:

• High blood pressure
• Irregular heart rhythm (arrhythmia)
• Heart failure
• Chest pain (angina)
• Heart attacks
• Glaucoma
• Migraines
• Generalized anxiety disorder
• Hyperthyroidism
• Certain types of tremors

Common side effects of beta blockers include fatigue, cold hands, dizziness and weakness. Less common side effects include shortness of breath, trouble sleeping, loss of sex drive and slow heartbeat.

Beta blockers generally aren't used in people with asthma because of concerns that the medication may trigger severe asthma attacks.

Beta blockers can also affect your lipid levels, causing a slight increase in triglycerides and a modest decrease in high-density lipoprotein, the "good" cholesterol. These changes often are temporary. You should not abruptly stop taking a beta blocker because doing so could increase your risk of a heart attack or other heart problems.