Quit-smoking basics
Learning Center
Heart rate: What's normal?
A normal resting heart rate for adults ranges from 60 to 100 beats per minute. A heart rate above or below that may signal a problem.
High blood pressure in children
Children can develop high blood pressure for the same reasons adults do — excess weight, poor nutrition and lack of exercise.
Home birth: Know the pros and cons
Understand the possible risks and how to plan and prepare for a home birth.
Hookah smoking: Is it safer than cigarette smoking?
This habit isn't safer than smoking cigarettes. Find out why.
Hormone therapy for prostate cancer
Find out what to expect during testosterone-blocking therapy. Learn about choices, including medicines and surgery.
How you hear
Your ears enable you to gather and interpret sounds from the world around you.
How your brain works
Which part of your brain does what? Take a tour.
Hydrocele
Find out more about the symptoms, causes and treatments for this swelling in the scrotum.
Hyperinsulinemia: Is it diabetes?
Hyperinsulinemia often is associated with type 2 diabetes.
Hypospadias
Hypospadias is a birth defect in which the opening of the urethra is located on the underside of the penis instead of the tip. Learn about treatment.