Comorbidities: Meaning and Common Examples

Co-occurring conditions are considered comorbidities

Comorbidities are distinct health conditions that are present (or are commonly present) at the same time. They may exist because of a shared cause or be entirely independent of one another.

For example, diabetes and coronary artery disease are comorbidities. They can co-occur because high blood sugar can damage blood vessels.

Comorbidities are important to consider because they can increase your risk of experiencing complications related to a diagnosis or developing a new health issue altogether.

People who have cancer, chronic lung or kidney disease, high blood pressure, obesity, HIV, or diabetes as comorbidities of COVID-19, for instance, are at higher risk for serious illness or death.

By being aware of comorbidities, your healthcare provider can ensure that the care you receive is both safe and sufficient enough to get (and keep) you well.

This article provides examples of common comorbidities, what causes them, and how they are treated.

Mental health and substance abuse support group
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Definition of Comorbidity

When a healthcare provider says you have a comorbidity, it means you have one or more conditions besides the one you are currently being treated for.

Comorbidities can exist in many different combinations. It is also possible to have more than one comorbidity at the same time.

Conditions described as comorbidities can be physical or mental in nature. They are typically chronic (long-term) concerns.

Healthcare providers also consider the possibility of common comorbidities when treating patients.

Also Known As

Other names for comorbidities include:

  • Co-occurring conditions
  • Coexisting conditions
  • Concomitant conditions
  • Concurrent conditions

Multimorbidity is a similar term, but is generally used to describe the presence of more than one condition—neither of which is considered more of a focus of treatment than the other.

Examples of Common Comorbidities

Physical illnesses such as diabetes and high blood pressure are often co-occurring conditions. Mental illnesses often co-occur with each other and with substance abuse. A comorbid condition can also include a physical illness and a mental illness (such as cancer and major depressive disorder).

Certain illnesses tend to co-occur with others for various reasons. It could be that the risk factors are the same for both diseases. This makes a person with one disease likely to get another one. Another possibility is when one disorder actually causes another.

Also, the symptoms of one illness can make a person more likely to develop another. For example, anxiety and depression can make a person likely to abuse drugs or alcohol.

Comorbidities of Obesity

Obesity is known to predispose people to many comorbid illnesses.

In fact, there are approximately 236 medical problems (including 13 types of cancer) linked with obesity, according to the Obesity Medicine Association.

Common comorbidities of obesity include:

  • Insulin resistance (a condition that is considered a precursor to type 2 diabetes)
  • Type 2 diabetes
  • High blood pressure
  • Dyslipidemia (high blood lipid levels including high cholesterol)
  • Cardiovascular disease
  • Stroke
  • Arthritis
  • Sleep apnea
  • Gallbladder disease
  • Hyperuricemia (excess levels of uric acid in the blood, a risk factor for gout)
  • Osteoarthritis
  • Certain types of cancer, such as breast cancer, colorectal cancer, and gallbladder cancer
  • Depression

Reasons why obesity and these other conditions are thought to be comorbid:

  • Carrying around excess weight can put physical stress on the joints resulting in comorbidities such as osteoarthritis. Excess weight can push on the chest and diaphragm. This can cause the soft tissues of the neck to collapse, leading to sleep apnea.
  • An increase in hormones and other substances secreted by adipose (fat) tissue impacts the endocrine system, resulting in diabetes and other metabolic conditions.
  • Physical and metabolic problems can harm the body's organs, such as the heart and kidneys.

Comorbidities of Diabetes

Common comorbidities of diabetes include:

Comorbidities of Asthma

People with asthma are more likely to develop respiratory comorbidities such as allergies, bronchitis, chronic obstructive pulmonary disease (COPD), and sinusitis.

But asthma is also associated with other comorbidities such as:

  • Obesity
  • High blood pressure
  • Bowel and bladder problems

Mental Health Comorbidities

According to the Substance Abuse and Mental Health Services Administration’s (SAMHSA) 2018 National Survey on Drug Use and Health, nearly 9.2 million adults in the United States have a comorbidity that includes substance abuse and a mental illness, or two types of mental illness, such as anxiety and depression.

Dual Diagnosis

A substance use disorder can involve alcohol or drug addiction (or both). Comorbid substance use disorder and mental illness is also called a dual diagnosis, and less frequently referred to as MICD (mental illness/chemical dependency).

The National Institute on Drug Abuse reports that nearly half of those who have one condition—either mental illness or substance abuse—also have the other.

Those with a substance use disorder are more likely to have a mental illness, and individuals with mental illness are more likely to have substance use disorder. One reason for this is that some symptoms of mental illness can cause people to self-medicate with drugs or alcohol.

Furthermore, chronic drug or alcohol use can have a negative influence on the brain, making a person more likely to develop mental illness.

Depression and Anxiety

One of the most common examples of comorbidity in the mental health field is depression and anxiety disorder. According to the National Alliance on Mental Illness (NAMI), some sources estimate that nearly 60% of those with anxiety also have symptoms of depression and vice versa.

Some of the most common mental health disorders in people with substance use disorder include mood and anxiety disorders such as:

  • Major depression
  • Persistent depressive disorder
  • Bipolar disorder
  • Post-traumatic stress disorder
  • Panic disorder
  • Social anxiety
  • Generalized anxiety disorder
  • Obsessive-compulsive disorder

Those with conditions considered to be serious and persistent mental illnesses (SPMI) are at the highest risk of having co-occurring mental health and substance use disorders. SPMI diagnoses, sometimes referred to as thought disorders, include:

  • Schizophrenia
  • Schizoaffective disorder (a chronic disorder that involves hallucinations, delusions and symptoms of a mood disorder)

Comorbidities of ADHD

ADHD is a common condition that affects between 5% and 8% of school-aged children. People with ADHD are described as "hyperactive" and "impulsive" and have difficulty paying attention. 

An estimated 60% to 100% of children diagnosed with ADHD have comorbidities. These can include:

  • Learning disorders
  • Anxiety disorders
  • Depressive disorder
  • Autism spectrum disorder
  • Bipolar disorder

Some research has found that people with ADHD may also have physical comorbidities such as gastrointestinal problems.

Treatment

Finding the right treatment for someone with comorbidities often requires consultation and planning between various healthcare providers and organizations. This applies to those with multiple mental health conditions as well as those with physical comorbidities.

Sometimes people may not want to share this information because of modesty or embarrassment. For example, a person with depression may not tell their healthcare provider that they're self-medicating with alcohol. This can make it challenging to find safe, effective treatment.

If you need to take medicine to treat two or more medical conditions, there is also a risk of drug interactions. This means one of your medicines may cause another to not work as well, or two or more medications may work together to create a dangerous side effect. This is why it is important to make sure all of your healthcare providers know what medicines you're taking and what conditions you're being treated for.

After being hospitalized, people with multiple health problems often need assistance and support from organizations such as home healthcare agencies and social services. These organizations can address situations such as being unable to work due to a major disability. They can also arrange for physical care, housing, and more.

Summary

Comorbidity means you have more than one illness (physical or mental) at once. There are many different causes of comorbidity. Some diseases, like obesity and diabetes or anxiety and depression, commonly overlap. There are many different theories for why certain diseases tend to be comorbid.

A Word From Verywell

Comorbidities can be challenging to live with. You may need to see a few different types of healthcare providers before you find the right treatment plan for you. Successful treatment may require a combination of medications and lifestyle changes. Sometimes treating one condition (such as obesity) can also cure the other (such as diabetes).

Frequently Asked Questions

  • Are comorbidities and complications the same thing?

    No. A comorbidity is a health condition that occurs at the same time as another. These issues can have shared causes or not. A complication is a direct side effect of a health condition.

  • Do comorbidities increase with age?

    Yes. The number of comorbidities you have can go up as you get older. This is because people tend to develop more health problems as they age.

  • What is the Charlson Comorbidities Index?

    The Charlson Comorbidities Index is a system used to predict mortality (how long someone will live) in people with comorbid conditions in order to determine how aggressively a condition needs to be treated.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Sherry Christiansen
Sherry Christiansen is a medical writer with a healthcare background. She has worked in the hospital setting and collaborated on Alzheimer's research.