How Do They Work?The full name for beta blockers is actually "beta-adrenergic blocking agents." As the name implies, these medications work by blocking beta receptors in the body. Beta receptors are located in a number of places within the body, including the heart and blood vessels. Stress hormones (such as adrenaline) bind to these receptors and cause certain reactions in the body, such as:
- Increasing the heart rate
- Increasing the force with which the heart pumps blood
- Increasing blood pressure (both systolic blood pressure and diastolic blood pressure)
- Opening the airways of the lungs (bronchodilation)
- Constricting blood vessels.
By blocking beta receptors, beta blockers cause the reverse effect of stress hormones. They lower the heart rate and both systolic and diastolic blood pressure. However, they can also cause a worsening of breathing problems, such as asthma and chronic obstructive pulmonary disease (by blocking the beneficial effects of stress hormones and related asthma medications in the airways).
It is not entirely clear how beta blockers work to prevent migraines or to improve survival after a heart attack. It is thought that they are probably useful for treating performance anxiety by preventing a racing heart. Beta blockers work for treating irregular and/or rapid heart rhythms by slowing down the conduction of the electrical signals in the heart. Beta blockers work for glaucoma (to lower the pressure in the eye) by decreasing the amount of fluid produced by the eye (known as aqueous humor).