My patient’s lungs were filled with blood, and he lay intubated in an ICU bed. His kidneys were failing, too. The cause of his illness was not a mystery: He had been previously diagnosed with an autoimmune disease that, in many cases, leads to severe organ damage, and he clearly needed the same treatment he’d received before, a drug that suppresses the immune system. With it, he started to improve in days.

At a follow-up visit, I suggested re-dosing the medication in a few months, to prevent future episodes of life-threatening inflammation. That word caught his attention. “What caused it?” he asked. “The inflammation, I mean.”

He and his wife exchanged uncertain glances as I explained that doctors don’t know what sets off most autoimmune inflammatory diseases: It’s likely a complex interplay between genetics, environment, and bad luck. But we do know how to treat them. At the next visit, his wife asked me about the potential causes of chronic inflammation that she’d read about online—tick bites, heavy-metal exposures, nutritional deficiencies—as well as anti-inflammatory treatments including herbal supplements, acupuncture, and energy healing. I began to worry that framing the conversation around inflammation—a word that clearly meant one thing to me and quite another to this couple—had been a mistake.

Doctors caring for patients with autoimmune diseases have long thought of inflammation i