Common Side Effects

• Side effects reported in more than 1 percent of patients include bradycardia (slow heartbeat), depression, diarrhea, dizziness, fatigue, pruritus (intense itching), rash, shortness of breath and vomiting. Call a doctor if they don't clear up.
  
  

Moderate Side Effects

• Approximately 1 percent of patients have reported experiencing arterial insufficiency, cold extremities, congestive heart failure, constipation, dry mouth, flatulence, heartburn, low blood pressure (hypotension), palpitations, peripheral edema and wheezing. Medical intervention is necessary if symptoms continue or worsen.
  
  

Infrequent Side Effects

• Fewer than 1 percent of patients develop difficulty breathing, nausea and stomach pain after taking Lopressor. Such side effects require immediate medical assistance.
  
  

Rare Side Effects

• Isolated side effects of using Lopressor include blurry vision, dry eyes, hair loss, Peyronie's disease (abnormal growths in the penis), the blood condition agranulocytosis and tinnitus (ringing in the ears). All require prompt medical care.
  
  

Warning

• Lopressor is generally unsafe for people with bronchospastic diseases because beta blockers may increase the risk of bronchospasms and impede proper breathing.