Physicians need to know how chemical intolerance affects people: Study

Chemical intolerance contributes to the illnesses of 1 in 5 patients but the condition seldom figures in their diagnosis, according to clinical research directed by a UT Medicine San Antonio physician.

Clinical tools are available to identify chemical intolerance but health care practitioners may not be using them, lead author David Katerndahl, M.D., M.A., said. The study is in the July 9 issue of Annals of Family Medicine. UT Medicine is the clinical practice of the School of Medicine at The University of Texas Health Science Center San Antonio.

Avoidance of triggers

The study's authors said physicians need to know how chemical intolerance affects certain people and understand that conventional therapies can be ineffective. Some patients would improve by avoiding certain chemicals, foods and even medical prescriptions, the authors said.

Patients with chemical intolerance go to the doctor more than others, are prone to having multi-system symptoms and are more apt to have to quit their job due to physical impairment, the authors said.

90-question survey

The study involved 400 patients who gave personal health information while waiting to be seen at primary care clinics in San Antonio, one in UT Medicine and the other in the University Health System. The researchers asked the patients to respond to 90 questions about their illnesses, mental health and ability to function.

In the end, the authors said, 20.3 percent of the patients questioned met the scientific criteria for chemical intolerance.

Patient inclusion

Researchers surveyed patients with chronic conditions such as allergies, asthma, diabetes and heart disease. They excluded patients who were at the clinics for acute conditions such as earaches, flu or bone fractures.

The origins of chemical intolerance have been the subject of much speculation, the authors acknowledge, but the condition is also understudied. People with chemical intolerance, or "CI," are highly sensitive to common substances such as cleaning products, tobacco smoke, fragrances, pesticides, new carpet and auto exhaust.

Important consideration in care

"Apart from the debate over causality, the fact that so many patients meet the criteria for chemical intolerance holds particular relevance for primary care providers," said Dr. Katerndahl, professor of family and community medicine who is supported by the Dr. Mario E. Ramirez Distinguished Professorship.

Chemically intolerant individuals often have symptoms that affect multiple organ systems simultaneously, especially the nervous system. Symptoms commonly include fatigue, changes in mood, difficulty thinking and digestive problems.