Dangerous Illnesses Made Worse by Extreme Heat

Several severe pre-existing medical conditions can be worsened by extreme heat. With temperatures well over 100°F in much of the Southwest and hovering near 100°F in the Northeast, the issue has become immediate and severe. Heat at these levels causes dehydration, which affects the body in several ways: it puts unusual strain on the heart, which in turn undermines the body’s ability to regulate temperature, and it can alter the effects of some medications.

Climate Crisis247 reviewed material from a number of medical and scientific sources, including the CDC Heat and Health Tracker, the Harvard Health article “Extreme Heat: Staying Safe if You Have Health Issues,” the WHO’s “Heat and Health” research, several scientific journals, and public health information from several states.

The pre-existing conditions most likely to be worsened by extreme heat include:

Heart disease

Coronary artery disease, heart failure, irregular heart rhythms, and high blood pressure all carry rising risk in extreme heat. As the heart works harder to cool the body, the risk of heart attack and heart failure increases.

Chronic kidney disease

Dehydration reduces blood flow to the kidneys, which can trigger acute kidney emergencies or worsen existing kidney disease.

Diabetes

Diabetes makes dehydration more likely and can impair sweating and circulation. The high blood sugar associated with diabetes also increases fluid loss.

Chronic lung diseases

Asthma and COPD (Chronic Obstructive Pulmonary Disease) can worsen because extreme heat often coincides with higher ozone and air pollution levels.

Neurological disorders

Parkinson’s disease, multiple sclerosis, dementia, and spinal cord injuries are among the conditions that can be worsened by high temperatures. Stroke-related disabilities may also undercut the body’s ability to regulate temperature.

Mental health conditions

Serious mental illnesses such as schizophrenia and bipolar disorder can increase heat risk, and some medications used to treat these conditions can cause additional problems in the heat.

Obesity

Excess body fat makes it more difficult for the body to dissipate heat.

Previous heat illness

Individuals who have experienced heat stroke or severe heat exhaustion are often more susceptible to future heat-related illness.

Alcohol or substance use disorders

When the body is overheated, alcohol and substance use can impair judgment, hydration, and the body’s ability to regulate temperature.