Foods, drugs and the environment are all reasons that some people experience allergic reactions. Explore the immune system and find out what leads to a misdirected immune response.

Asthma can be a debilitating condition, and a number of factors can trigger an attack. Fortunately, there are treatments available to help those with asthma lead relatively normal lives.

Arthritis is defined as the inflammation of joints, and symptoms include stiffness and pain. It often afflicts older people's hands, inhibiting mobility and fine motor skills. Learn about the causes of arthritis and how it can be treated.

This section covers cancer types, causes and symptoms as well as the signs of cancer, tests and treatments.

Cold and flu can be extremely contagious and are usually more common at certain times of the year. Learn about the differences between the common cold and the flu, as well as symptoms and effective treatment methods.

From minor tension headaches to severe migraines, the articles in this section explain what's behind your headache and how it can be effectively -- and safely -- treated.

Understand diabetes and how your body uses insulin to handle glucose. You'll also find information about the impact of diabetes on other systems in the body.

Osteoporosis, the thinning of bone tissue and loss of bone density over time, can be prevented with proper nutrition and lifestyle choices. Learn about the causes of osteoporosis as well as effective methods for treatment and prevention.

 Digestive

Digestive acids that end up in the wrong place can cause heartburn and stomach ulcers. Find out how to maintain your digestive health and treat painful symptoms.

Whether your pain is the result of a health condition or not, learning to manage your pain can make everyday life more bearable. Learn about pain management through lifestyle choices and modern medicine.

Bird flu, malaria, plague and West Nile virus are infectious diseases we've all heard of. Find information on these epidemics and more in this section.

Musculoskeletal conditions can occur in many parts of the body. Find information on chronic conditions such as arthritis, back pain and foot pain.

Respiratory conditions impact the lungs and the ability to breath. In this section, find out about the symptoms and treatment of apnea, orthopnea and more.