What are the most common pre-existing medical conditions?

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The most common pre-existing medical conditions include high blood pressure, diabetes, asthma, depression, and cancer.

A pre-existing condition is any health issue, chronic illness, or injury diagnosed or treated before starting a new insurance policy.

Most Common Pre-Existing Conditions

  • High Blood Pressure (Hypertension): Affects millions of adults and impacts standard health and travel insurance underwriting.
  • Diabetes (Type 1 and Type 2): Requires ongoing daily medication management.
  • Asthma and COPD: Chronic respiratory issues causing breathing difficulties or unexpected flare-ups.
  • Mental Health Disorders: Includes diagnosed depression, anxiety, and bipolar disorder.
  • Cancer: Encompasses active diagnoses as well as conditions in remission.
  • High Cholesterol: Frequently monitored with routine blood tests and prescriptions.
  • Arthritis and Joint Disease: Inflammatory joint conditions and chronic back or joint pain.
  • Obesity: Categorized as severe or extreme under standard medical underwriting metrics.

What are the 20 most common diseases?

The most common global health conditions and widespread chronic or infectious diseases include everyday ailments and major public health issues.

Widespread Common Diseases and Conditions

  • Common Cold: A viral infection of the upper respiratory tract caused by rhinoviruses and others.
  • Influenza (Flu): A contagious viral respiratory illness causing fever, cough, and body aches.
  • Dental Caries (Cavities): Tooth decay resulting from bacterial activity and poor oral hygiene.
  • Tension Headaches & Migraines: Extremely frequent neurological events causing head pain.
  • Seasonal Allergies (Allergic Rhinitis): Immune reactions to pollen, dust, or pet dander.
  • Gastroenteritis (Stomach Flu): Viral or bacterial intestinal infections causing diarrhea and vomiting.
  • Hypertension (High Blood Pressure): A chronic cardiovascular condition increasing heart attack and stroke risks.
  • Type 2 Diabetes: A metabolic disorder involving insulin resistance and high blood sugar.
  • Anxiety Disorders: Persistent, excessive worry affecting mental health.
  • Major Depressive Disorder: A common mood disorder causing prolonged sadness and loss of interest.
  • Asthma: A chronic respiratory disease causing airway inflammation and wheezing.
  • Gastroesophageal Reflux Disease (GERD): Chronic digestive acid reflux irritating the food pipe lining.
  • Acne Vulgaris: A widespread inflammatory skin disease affecting hair follicles and oil glands.
  • Fungal Nail Infections (Onychomycosis): Common fungal infections leading to discolored, brittle nails.
  • Urinary Tract Infections (UTIs): Bacterial infections affecting the bladder or kidneys.
  • Bronchitis: Inflammation of the main air passages leading to the lungs.
  • Ischemic Heart Disease: Cardiovascular narrowing of heart arteries leading to chest pain or attacks.
  • Stroke: Interrupted blood supply to part of the brain.
  • Chronic Obstructive Pulmonary Disease (COPD): Long-term lung damage causing breathing difficulty.
  • Human Papillomavirus (HPV): A very prevalent sexually transmitted viral infection.

What is the list of pre-existing conditions?

A pre-existing condition is any physical or mental health problem that you have or received treatment for before a new insurance policy starts.

There is no single official master list because insurance companies, travel insurers, and health programs define them broadly. Any ongoing, historical, diagnosed, or even undiagnosed medical issue can qualify.

Common Examples of Pre-Existing Conditions

  • Diabetes (Type 1 and Type 2)
  • Asthma and chronic respiratory diseases
  • Cancer (active or in remission)
  • High blood pressure (hypertension) and high cholesterol
  • Heart disease or cardiovascular conditions
  • Mental health conditions (such as depression, anxiety, or bipolar disorder)
  • Neurological disorders (like epilepsy, Parkinson's disease, or multiple sclerosis)
  • Autoimmune diseases (such as lupus or Crohn's disease)
  • Pregnancy

How Insurance Views These Conditions

  • Standard Health Insurance (USA): Under the Affordable Care Act (ACA), health insurance providers cannot deny you coverage, charge you more, or refuse to cover treatment for a pre-existing condition.
  • Travel and Life Insurance: These policies routinely use medical underwriting. They require you to disclose past illnesses or injuries and may exclude or charge extra for unmanaged pre-existing issues unless you buy specialized coverage.

You can read more about definitions and protections through the official HealthCare.gov Guide.

What pre-existing conditions are not covered?

Under standard Affordable Care Act (ACA) health insurance plans in the United States, no pre-existing conditions can be excluded or left uncovered.

ACA-Compliant Plans

  • What is covered: Every pre-existing condition—including diabetes, cancer, asthma, heart disease, and pregnancy—is fully covered from day one.
  • Protections: Insurers cannot deny you coverage, charge you higher rates, or refuse to pay for treatments based on your health history.
  • Where to find them: These rules apply to all Marketplace plans on HealthCare.gov, Medicaid, CHIP, and most job-based health plans.

Plans That Do Not Cover Pre-Existing Conditions

Not all health plans follow ACA rules. You may face exclusions or denials for pre-existing conditions in these specific categories:

  • Short-Term Health Insurance: Temporary plans can deny coverage or exclude your past medical issues.
  • Grandfathered Individual Plans: Policies you bought for yourself before March 23, 2010, do not have to cover pre-existing conditions.
  • Certain Travel or Supplemental Insurance: Standard travel or indemnity policies often exclude specific ongoing or chronic health problems unless you buy a specialized waiver.

What qualifies as a pre-existing medical condition?

A pre-existing medical condition is any physical or mental health issue, chronic disease, or injury that existed or showed symptoms before a new insurance policy or healthcare plan begins.

What Qualifies

  • Diagnosed Illnesses: Conditions officially identified by a doctor, such as diabetes, cancer, asthma, epilepsy, or heart disease.
  • Undiagnosed Symptoms: Ongoing health problems or pain where symptoms were already present, even if you never received a formal medical diagnosis.
  • Active Treatments: Any issue for which you recently took prescription medication, received medical advice, or underwent testing.
  • Past Episodes: Major past health events (like a prior stroke or cancer in remission) that remain part of your medical history.

Insurance Rules

  • Standard Health Insurance (USA): Under the Affordable Care Act, standard individual and group health plans cannot deny you coverage, charge you more, or refuse treatment for a pre-existing condition.
  • Travel or Private Insurance: Many travel insurance or short-term medical plans still have strict look-back periods (often 60 to 180 days before policy purchase) and may exclude or require extra payment to cover pre-existing conditions if they are not fully disclosed. You can review guidelines directly at HealthCare.gov.

These common medical conditions are considered 'preexisting'

9 related questions found

What is the #1 disease in the world?

Cardiovascular disease (heart disease) is the number-one killer disease in the world.

Key Facts About Heart Disease

  • Global Impact: According to the World Health Organization (WHO), ischemic heart disease (coronary artery blockage) is the leading cause of death globally.
  • Death Toll: It causes about 16% of all deaths worldwide, taking roughly 9.5 million lives each year.
  • What It Does: It includes conditions that narrow or block blood vessels, leading to heart attacks and strokes.

Top Risks You Can Control

  • High blood pressure
  • Smoking tobacco
  • Unhealthy diet and high cholesterol
  • Lack of physical exercise

What About Infectious Diseases?

If you look only at diseases spread by germs, tuberculosis (TB) is the world's leading infectious killer, causing over a million deaths a year.

Can you give me a list of common illnesses?

Common illnesses include everyday infections, breathing issues, and long-term health conditions.

Respiratory Infections

  • Common Cold: A viral nose and throat infection causing sneezing, a runny nose, and a cough.
  • Influenza (Flu): A stronger virus that brings sudden fever, body aches, and tiredness.
  • Bronchitis: Swelling in the main airways of the lungs that leads to a deep, mucus-filled cough.
  • Pneumonia: A lung infection that fills air sacs with fluid or pus.

Stomach and Digestive Illnesses

  • Gastroenteritis (Stomach Flu): Gut inflammation causing vomiting and diarrhea.
  • Gastroesophageal Reflux Disease (GERD): A chronic condition where stomach acid flows back up and irritates the food pipe.

Common Chronic Conditions

  • Hypertension (High Blood Pressure): Extra force of blood against artery walls, often called a silent condition.
  • Diabetes: Trouble making or using insulin, which controls blood sugar.
  • Asthma: Long-term airway narrowing that causes wheezing and shortness of breath.

Common Contagious Diseases

  • Chickenpox: An itchy rash with small blisters caused by a virus.
  • Strep Throat: A bacterial infection causing a very painful throat.
  • Conjunctivitis (Pink Eye): Eye redness and irritation from bacteria, viruses, or allergies.

For a complete directory of symptoms and medical advice, visit the NHS Conditions A to Z.

What are the most common pre-existing conditions?

High blood pressure (hypertension), behavioral health disorders, and high cholesterol are the most common pre-existing health conditions affecting tens of millions of people.

A pre-existing condition is any medical issue, chronic illness, or previous diagnosis that existed before a new healthcare or insurance plan began.

Most Common Pre-Existing Conditions

According to data from the U.S. Department of Health and Human Services, the most prevalent conditions include:

  • High blood pressure (Hypertension): Affects roughly 44 to 46 million people.
  • Behavioral health and mental disorders: Includes depression and anxiety, impacting about 45 million people.
  • High cholesterol (Hyperlipidemia): Affects around 44 million people.
  • Asthma and chronic lung disease: Impacts about 34 million people.
  • Osteoarthritis and joint disorders: Affects roughly 34 million people.
  • Diabetes: Affects 13 million or more individuals.
  • Heart conditions: Impacts roughly 16 million people.
  • Cancer: Affects an estimated 11 million people with a prior history.

Other frequent conditions include sleep apnea, extreme obesity, epilepsy, and even past pregnancy.

Insurance and Coverage Rules

  • ACA-Compliant Plans: Under the Affordable Care Act, marketplace and most standard health plans cannot deny you coverage, charge you more, or refuse to treat these common conditions.
  • Short-Term or Non-ACA Plans: These alternative plans may still exclude pre-existing conditions or require waiting periods before providing care.

How far back is a pre-existing condition?

A pre-existing condition look-back period typically ranges from 60 to 180 days for travel insurance or up to 6 to 12 months for standard health applications, though it depends heavily on the type of insurance.

How Look-Back Periods Work by Insurance Type

  • Health Insurance (ACA-Compliant): Under the Affordable Care Act, standard health insurance plans cannot look back at your medical history to deny coverage, drop you, or charge you more for a pre-existing condition. There is no look-back or exclusion period for major medical health plans.
  • Travel Insurance: Most plans use a look-back period of 60 to 180 days right before you buy the policy to see if you received treatment, new medications, or advice for a condition. If your condition was stable and you did not need treatment during that window, it may be covered.
  • Medigap (Medicare Supplement): If you apply outside your initial enrollment window, companies can look back 6 months at your medical history and impose a waiting period of up to 6 months for pre-existing conditions in most states.
  • Disability or Life Insurance: Underwriters may review anywhere from 2 to 5 years (or more) of your medical records to assess your risk profile.

What are the 25 critical illnesses?

A standard 25-condition critical illness insurance policy typically covers a core group of life-threatening health events, though the exact list can vary slightly by insurance provider.

Common 25 Critical Illnesses Covered

Most basic plans or standard industry benchmarks include the following conditions:

  • The "Big Three": Cancer (of specified severity), Heart Attack (myocardial infarction), and Stroke.
  • Neurological & Brain Conditions: Alzheimer's disease / Dementia, Benign Brain Tumour, Coma, Motor Neuron Disease, Multiple Sclerosis, and Parkinson's disease.
  • Organ & Cardiovascular Surgeries: Coronary Artery Bypass Surgery, Aortic Surgery, Heart Valve Replacement, Kidney Failure, Major Organ Failure, and Major Organ Transplant.
  • Functional & Sensory Losses: Blindness, Deafness, Paralysis, Loss of Speech, Loss of Limbs, and Loss of Independent Existence.
  • Blood & Systemic Conditions: Aplastic Anemia, Bacterial Meningitis, Severe Burns, and Occupational HIV.

You can review a standard layout of these plans through providers like Car Nation Canada or ivari.