10 Misdiagnosed Illnesses That Can Cause Serious Problems

Stay informed and stay safe.

It's a patient's (and a doctor's) worst nightmare: A misdiagnosed condition that turns out to be something serious. About 12 million American adults are misdiagnosed each year in outpatient visits, and a study in BMJ estimated that nearly 795,000 people become disabled or die because of misdiagnosis annually. Some conditions are more commonly misdiagnosed than others. According to a January 2022 study published in JAMA Network Open, these are the ten most common misdiagnosed illnesses that can cause serious problems.

Brain Hemorrhage

Doctors watching x-ray of patient.

According to the Cleveland Clinic, symptoms of a brain hemorrhage include headache, nausea and vomiting or sudden tingling, weakness, numbness or paralysis of the face, arm, or leg. 

Pulmonary Embolism


A pulmonary embolism is a sudden blockage in the pulmonary arteries, the blood vessels that bring blood to your lungs. It usually happens when a blood clot in the deep veins in your leg breaks off and travels to the lungs, Penn Medicine says. Common symptoms include cough, rapid heartbeat, lightheadness or dizziness, sweating and fever.

Bladder Cancer


The most common symptom of bladder cancer is blood in the urine, which can be misdiagnosed as something less serious, like a urinary tract infection. So can other symptoms like frequent urination and pain while urinating.



Sepsis is an extreme reaction to infection, and its symptoms—fever, difficulty breathing, low blood pressure, fast heart rate, and confusion—can be confused for other conditions or overlooked.



Classic stroke symptoms, such as weakness on one side of the body, often result in a correct diagnosis. But doctors miss about 40 percent of strokes that present with dizziness, David Newman-Toker, M.D., a professor of neurology, ophthalmology and otolaryngology at Johns Hopkins, told AARP.

Prostate Cancer

hand holding bathroom door, toilet

Prostate cancer was the fourth-most commonly misdiagnosed condition, the study found. "Prostate cancer is one of the most asymptomatic cancers in oncology, which means that not all men experience symptoms and many times these symptoms can be mistaken or attributed to something else," the Prostate Cancer Foundation says. Common symptoms include frequent urination, difficulty starting or stopping urination, weak or interrupted urine flow, painful or burning while urinating, blood in the urine or semen, or frequent pain and stiffness in the lower back, hips, or upper thighs.

Heart Attack


The most common symptom of a heart attack is chest pain, but other nontraditional symptoms (such as nausea and vomiting) can be missed, particularly in women, experts say. 

Breast Cancer


Breast cancer was the third-most-common misdiagnosis in the JAMA study, in which researchers identified several potential pitfalls that result in misdiagnosis. In the case of breast cancer, one was a doctor ordering screening instead of a mammogram to assess a breast lump.

Lung Cancer


In the case of lung cancer, the researchers said a common diagnostic error is misreading a lung tumor as pneumonia on a chest X-ray. A common symptom—a chronic cough—may also be dismissed as something less serious. 

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Colorectal Cancer


Colorectal cancer was the most commonly misdiagnosed condition, comprising 5% of misdiagnoses in the study sample. The gold-standard test for diagnosing colorectal cancer is a colonoscopy. Other less invasive tests are available, such as fecal occult tests and stool-based DNA testing, but they're less effective. The American Cancer Society's latest guidelines recommend that colorectal cancer screenings begin at age 45. 

Michael Martin
Michael Martin is an experienced writer and editor in New York City. He specializes in helping people make life-improving decisions on their health, nutrition, finances, and lifestyle. Read more
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