How the mind and body interact to influence health has long been discussed. The term psychosomatic expresses this interaction. Paired with disorder, the term was once used to refer to physical symptoms that appear to be caused or worsened by mental factors, rather than by a physical disorder. Now, the term somatoform disorders is used to refer to these disorders. The term does not imply that physical symptoms are imagined or are being faked (as in Munchausen syndrome). People with a psychosomatic disorder actually experience the symptoms.

The mind and body interact in many other ways.

Social and mental stress can aggravate many physical disorders, including diabetes mellitus, coronary artery disease, and asthma. Such stress can trigger, worsen, or prolong physical symptoms.

Stress can cause physical symptoms even when no physical disorder is present. Sometimes physical symptoms result from the body's automatic response to emotional stress, as when heart rate and blood pressure increase in response to fear.

Sometimes a physical symptom appears to be a metaphor for an emotional experience, as when people with a “broken heart” have chest pain. Or a physical symptom may reflect identification with another person's pain. For example, people may have chest pain after a family member or friend has had a heart attack.

Physical symptoms can evolve from stress or mental symptoms in anyone, including people who do not have a serious underlying mental health disorder. Such physical symptoms are often mild and transient. They can be difficult for a doctor to diagnose, and various diagnostic tests may be required to eliminate the possibility of an underlying physical disorder.

Mental factors can also influence the course of a disorder. For example, people with high blood pressure may deny having it or deny its seriousness. Denial is a defense mechanism that helps reduce anxiety. However, denial may prevent people from following their treatment plan. For example, they may not take their prescribed drugs, thus worsening their disorder.

Conversely, a physical disorder can influence or lead to a mental condition. For example, people with a life-threatening, recurring, or chronic physical disorder may become depressed. The depression, in turn, may worsen the effects of the physical disorder.