By Michael J. Critelli | MakeUsWell Newsletter, 

Recently, actress Christina Applegate reported during an episode of her podcast, MeSsy, that her doctor says she doesn’t have the autoimmune disease and was misdiagnosed. She said that her doctor reported this happily to her, but she was both depressed and angry.  She said that she still had debilitating symptoms, but that she was back to square one in figuring out what was wrong and what she could do about it.

A person struggling with fatigue, digestive distress, joint pain, or unexplained weakness may receive familiar advice: eat better, exercise more, reduce stress, and get enough sleep. Those recommendations can help. But what if an undiagnosed or misdiagnosed condition changes what “better” actually means?

Autoimmune diseases occur when the immune system mistakenly attacks the body’s own tissues. Identifying them can require assembling clues across symptoms, examinations, laboratory results, and time. When diagnosis goes wrong, the consequences extend beyond delayed medication. They can shape everyday choices about food, supplements, activity, and rest.

Why the diagnosis can take so long and often be wrong

Early symptoms often resemble more common problems. Fatigue may suggest poor sleep or depression; digestive discomfort may suggest irritable bowel syndrome; joint pain may be attributed to aging or overuse. Several explanations can initially seem reasonable.

The disease itself may also evolve. Symptoms can appear intermittently, and the findings needed to distinguish one condition from another may emerge gradually. Some diagnostic delays reflect genuine uncertainty rather than an avoidable mistake.

Testing does not always settle matters. A positive autoimmune screening test is a clue, not a diagnosis of an autoimmune disease: up to 15% of healthy people test positive for antinuclear antibodies that signal an autoimmune disease that they may or may not have, so clinicians must interpret the result alongside symptoms and other findings. A laboratory result needs interpretation within the patient’s broader clinical picture.

Fragmented care adds another challenge: different specialists may see separate pieces of the problem. An early explanation can also become an anchor, influencing how subsequent symptoms are interpreted.

Patients’ concerns may be prematurely attributed to psychological causes. An international survey of 6,607 adults with autoimmune diseases, published in October 2026, found that approximately 43% of women and 33% of men reported such an attribution. These were patient-reported experiences, not independently verified diagnostic errors, but they raise serious concerns about listening and reassessment.

How a missed diagnosis changes daily choices

Consider celiac disease. Someone who believes the problem is ordinary digestive sensitivity may eliminate various foods while continuing to consume gluten. Confirmed celiac disease requires lifelong gluten avoidance. Yet beginning that diet before diagnostic testing can make the condition harder to identify. The sequence of decisions matters.

Autoimmune gastritis presents another problem. A person with iron or vitamin B12 deficiency may try eating more nutrient-rich foods. But the disease can impair absorption. Improving intake alone may be insufficient; appropriate replacement and medical management may be needed.

Supplements can create the opposite difficulty. Someone seeking more energy may purchase iodine-containing “thyroid support” products. In autoimmune thyroid conditions such as Hashimoto’s or Graves’ disease, excess iodine can worsen dysfunction.

Even general advice to reduce salt has exceptions. Some people with Addison’s disease and low aldosterone benefit from additional sodium under professional guidance. Diet supports, rather than replaces, essential medical treatment.

The lifestyle implication is equally important: unexplained weakness or exhaustion should prompt investigation, rather than an automatic assumption that the person needs greater discipline. Activity plans should reflect the underlying condition and current capabilities.

Does reimbursement encourage premature certainty?

Our payment system deserves scrutiny. Fee-for-service arrangements can create pressure for visit volume, while complex diagnosis requires time, coordination, and reconsideration. The National Academies has identified payment structures as a potential barrier to diagnostic quality.

That pressure may encourage premature closure: accepting a plausible explanation before adequately considering alternatives. However, blaming ICD-10 coding alone would be inaccurate. These codes classify diagnoses and symptoms; they do not establish clinical truth.

Outpatient coding rules explicitly permit reporting symptoms or abnormal findings when a definitive diagnosis has not been established. Medicare also allows most evaluation and management visit levels to reflect medical decision-making or time. Providers need not manufacture certainty to submit a claim.

We should reward careful investigation, explain uncertainty honestly, and revisit diagnoses when treatment fails or new evidence appears.

For patients, one valuable question is: “What does this diagnosis explain, what remains unexplained, and what would make us reconsider it?”

For MakeUsWell, the lesson is fundamental: sound nutrition and lifestyle guidance begins with understanding the person’s actual condition. A healthy choice depends on context and sometimes that context is still being discovered.