Don't smoke, and avoid secondhand smoke, areas with high air pollution, and elevations over 5,000 feet. Losing weight and exercising regularly can help.

See a doctor immediately if:

• Sudden and severe
• Occurs at rest
• Chest pain, cold sweats, fainting, or nausea
• Blue tinge to lips or fingers
• Can't work or complete daily tasks

Make an appointment to see a doctor if:

• Swelling in ankles and feet
• Wheezing
• Fever and cough
• Worsens when lying flat