Patients should not take bronchodilators, unless prescribed by a physician, if they have been diagnosed with any of the following conditions:

• Heart or blood vessel disease. Bronchodilators may worsen these conditions.
  
  
• High blood pressure. Some types of bronchodilators may elevate blood pressure.
  
  
• Arrhythmias (abnormal heart rhythms). Some type of bronchodilators may worsen these conditions.
  
  
• Hyperthyroidism (overactive thyroid). Chances of bronchodilator side effects may be increased.
  
  
• Pheochromocytoma (a rare and usually benign cell tumor that produces adrenaline, raising blood pressure and heart rate). Bronchodilators may raise blood pressure and heart rate.
  
  
• Urinary problems. Bronchodilators may not be recommended for people with urinary problems because they may reduce urine output.
  
  
• Glaucoma. Bronchodilators may not be recommended for people with glaucoma.
  
  
• Viral illnesses. These conditions can alter the way a person's body responds to certain bronchodilators.
  
  
• Pregnancy. Some studies have shown birth defects in animals when given large doses of bronchodilators. Patients are advised to consult their physician.