Serious side effects of beta blockers can occur. But studies show they are very uncommon. They include:

  • Heart problems such as worsening heart failure or slow heart rate
  • Breathing problems such as asthma
  • Allergic reactions

People taking beta blockers usually have less symptoms than those taking a placebo. A placebo is sometimes called a “sugar pill”.

Heart Problems

Makers of beta blockers warn that they may worsen or cause heart failure. This is especially true with long-term use. Other types of heart problems include slow pulse, irregular heartbeat, and heart attack.

One study of people with high blood pressure found that 6 out of 1,000 people on nebivolol developed heart problems. These included heart attack and heart failure. This is compared to none on placebo.

Many other studies disagreed. They found that beta blockers reduced the risk of admission to the hospital for heart problems. For example, one study compared the beta blocker carvedilol to placebo. This study included people with severe heart failure. 24 out of 100 people on placebo had their heart failure get worse. This is compared to only 17 out of 100 people on carvedilol. 6 out of 100 people on placebo had sudden death. Only 4 on carvedilol had sudden death. Other serious side effects occur less often on carvedilol.

Breathing Problems

Rarely, people on beta blockers develop breathing problems. One study compared the beta blocker metoprolol to placebo. The study included people who survived a heart attack. They found that no one on placebo had breathing problems. However, 2 out 1,000 people on beta blocker experienced side effects. These mainly included asthma or tightening of lung airways (also known as bronchospasm).

Allergic Reactions

All medicines can cause an allergic reaction in some people. Rarely, beta blockers may make your severe allergic reactions worse. They may also keep your medicines for these severe allergies from working as well as usual. This may be dangerous for people who need to use epinephrine (e.g. EpiPen). But it is very rare for people taking a beta blocker to have an allergic reaction. In one study, less than 2 out of 1,000 people on beta blockers had severe allergic reactions.

Seek immediate medical help if you have any of these symptoms while taking a beta blocker:

  • Difficulty breathing
  • Swelling of the face, lips, tongue, or throat
  • Chest pain

Studies show that taking beta blockers helps your heart’s health. This benefit often outweighs the risk of side effects. But everyone is different. Talk to your doctor about what is best for you.

When in doubt, seek medical help!