Depending on the type of beta blocker prescribed, patients may experience one or more side effects, including:

• Allergic reaction (sneezing, respiratory congestion, itching or skin rashes)
  
  
• Bradycardia (slow heart rate)
  
  
  
  
  
• Worsening of heart failure
  
  
• Drowsiness, weakness or fatigue
  
  
• Cold hands and feet, or an increased general sensitivity to cold
  
  
• Dizziness or lightheadedness, especially after getting up from a standing or lying position
  
  
• Headache or ringing in ears (tinnitus)
  
  
• Shortness of breath (dyspnea) or wheezing
  
  
• Fainting (syncope)
  
  
• Vivid dreams, nightmares, depression, memory loss and (rarely) hallucinations
  
  
• Increase in cholesterol levels
  
  
• Increased insulin resistance (except with carvedilol)
  
  
• Erectile dysfunction (impotence)
  
  
• Reduced sex drive in both men and women
  
  
• Abdominal cramps or (rarely) diarrhea, constipation and/or nausea

Patients who experience side effects from beta blockers should contact their physician immediately, but should not stop taking the medication. Abrupt discontinuation may lead to angina or heart attack in patients with coronary artery disease. Stopping beta blocker use too quickly can also worsen the symptoms of patients who have an underactive thyroid (hypothyroidism). Therefore, all patients are encouraged to speak to their physicians before making any changes in how they are taking beta blockers.