While beta blockers can be extremely useful in reducing blood pressure and treating certain heart conditions, they are not always an ideal treatment. Contraindications for beta blockers need to be carefully considered, as the medication may worsen some conditions or mask the symptoms of complications. Some of the contraindications for beta blockers include diabetes, asthma, partial heart block, and a slow heart rate.
One of the most common contraindications for beta blockers is the existence of either type I or type II diabetes. Diabetics are prone to a condition known as hypoglycemia, or extremely low blood sugar, which may be signaled by symptoms such as dizziness, chills, and increased heart rate. Since beta blockers work by reducing adrenaline in the blood stream and slowing the heart rate, important symptoms of hypoglycemia can be masked by the medication. For this reason, beta blockers are rarely prescribed for diabetics, especially those who rarely experience the outward symptoms of hypoglycemia.
In the quest of beta blockers to reduce blood pressure, they can also cause a narrowing of the airways known as bronchoconstriction. This action can make it more difficult to breathe, which may not be an issue for healthy patients, but can wreak havoc on patients with asthma. Asthma is one of the most critical contraindications for beta blockers, since the use of the drugs can bring on sudden, violent asthma attacks that can lead to hospitalization and death. Even patients with mild asthma, or those who experienced asthma as a child, but not as an adult, may be advised against using beta blockers.
The side effects from beta blockers include some cardiovascular changes that may present dangers to patients with heart conditions. Cardiovascular contraindications for beta blockers frequently include the presence of heart block, a condition in which the electrical signals from the chambers of the heart do not always transmit correctly, leading to an irregular heartbeat. Beta blockers can increase the irregularity, worsening heart block and leading to an increased potential for heart failure or unstable heart rhythms.
A slower than normal heartbeat, known as bradycardia, can also be dangerous when combined with beta blockers. Since the main action of these drugs is to reduce heart rate, the presence of bradycardia can lead to an extremely low heart rate that is unsustainable. In cases where beta blockers are prescribed regardless of this contraindication, patients may experience more severe side effects from the drug, and may be at an increased risk for heart failure.