Shingles is caused by the varicella zoster virus, the same virus that causes chickenpox. After a person recovers from chickenpox, the virus stays in the body in a dormant (inactive) state. For reasons that are not fully known, the virus can reactivate years later, causing shingles. Almost 1 out of every 3 people in the United States will develop shingles, also known as zoster or herpes zoster. There are an estimated 1 million cases each year in this country. Anyone who has recovered from chickenpox may develop shingles; even children can get shingles. However the risk of disease increases as a person gets older. About half of all cases occur among men and women 60 years old or older.

Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder, meaning it is a problem caused by changes in how the GI tract works. People with a functional GI disorder have frequent symptoms, but the GI tract does not become damaged. IBS is not a disease; it is a group of symptoms that occur together. The most common symptoms of irritable bowel syndrome are abdominal pain or discomfort, often reported as cramping, along with diarrhea, constipation, or both. In the past, irritable bowel syndrome was called colitis, mucous colitis, spastic colon, nervous colon, and spastic bowel. The name was changed to reflect the understanding that the disorder has both physical and mental causes and is not a product of a person's imagination.