Extreme heat does not only cause temporary physical discomfort, but can also have serious negative effects on health, sometimes requiring hospitalization. Children, babies, individuals with chronic illnesses, pregnant women and the elderly are the most vulnerable groups. Fortunately, there are several measures we can take to protect ourselves from these effects.

Learn what happens when you stay in extreme heat, the effects on mental health, and how to prevent the consequences of extreme heat on health.

High temperatures can have numerous health consequences. Here’s what happens when you stay in extreme heat:

1. Dehydration and electrolyte imbalances

As stated by Better Health Channel, extreme heat leads to significant losses of fluids and electrolytes (potassium, sodium and other minerals) through sweating, especially if you do not drink enough water. According to Cleveland Clinic, dehydration increases the risk of severe electrolyte imbalances, heat-induced illnesses, organ failure and death. Dark-colored urine, less frequent urination, dizziness, headaches and thirst are some symptoms of dehydration.

1. Heat cramps

Heat cramps are characterized by muscle cramps in the legs, arms and abdomen. They occur after engaging in physical activities in very hot environments, representing the mildest form of heat-induced illness.

1. Heat exhaustion

Heat exhaustion is a serious heat-induced illness that can quickly progress to heatstroke, the most severe form of these conditions. Heat exhaustion occurs when the body’s temperature reaches 38-39 degrees Celsius and manifests as:

• Sweating;

• Pallor;

• Rapid pulse;

• Dizziness;

• Weakness;

• Fainting;

• Headaches;

• Nausea and vomiting.

1. Heatstroke

Heatstroke occurs when the body’s temperature exceeds 40 degrees Celsius and is a life-threatening condition, especially for vulnerable individuals, such as children and those with chronic illnesses. Heatstroke can restrict blood flow to internal organs, causing fatal complications. Among the symptoms of heatstroke are:

• Agitation;

• Confusion;

• Rapid pulse;

• Rapid breathing;

• Muscle spasms;

• Seizures;

• Sweating;

• Hot, dry skin;

• Loss of consciousness.

1. Heat rash

Heat rash, or miliaria, is a skin irritation caused by heat and excessive sweating, commonly affecting infants and young children. It presents as redness of the skin accompanied by itching, inflammation and small red spots. It generally occurs in areas, such as the groin, neck, under the breasts, on the chest and armpits or in skin folds.

1. Complications of chronic conditions

Excessive heat exacerbates pre-existing conditions, such as cardiovascular diseases, respiratory disorders (e.g. asthma), diabetes and its complications, and mental health disorders (schizophrenia, depression, dementia). Moreover, it can trigger major cardiovascular events, such as acute myocardial infarction and stroke, but can also cause acute renal conditions.

Sometimes, vulnerability is also influenced by medications, such as psychotropic drugs, which can affect the body’s ability to regulate temperature, as noted by Moustaq Karim Khan Rony and Hasnat M. Alamgir in the study "High temperatures on mental health: Recognizing the association and the need for proactive strategies—A perspective".

As highlighted in the aforementioned study, prolonged exposure to extreme heat also causes several mental changes. These include:

• Increased Stress Levels: Excessive heat activates the body’s stress response, such as the production of cortisol and adrenaline (stress hormones). This affects the mood, leading to agitation and irritability. In extreme heat, the ability to cope with stressors decreases, making you less tolerant or patient. This can have a significant impact on relationships;

• Sleep Disorders: Due to its effects on the body, a heatwave can disrupt the circadian rhythm, leading to insomnia, frequent nighttime awakenings or poor sleep quality;

• Impaired Cognitive Functions: Heat-induced stress affects memory, attention, concentration, motivation and decision-making abilities, interfering with daily activities;

• Risk of anxiety and depression: A heatwave can induce feelings of anxiety, sadness and a sense of loss of control, leading to abrupt mood changes and increased emotional sensitivity. As a result, it can exacerbate symptoms of pre-existing mental health disorders, such as anxiety and depression;

• Increased hospitalization: During heatwaves, there is a marked increase in hospitalization rates due to mental health disorders, such as depression and bipolar disorder;

• Increased Suicide Rates: According to the study "Temperature-related mortality in China from specific injury" (Jianxiong Hu et al.), every 1 degree Celsius increase in the average monthly temperature corresponds to a 1% increase in the suicide rate.

According to the World Health Organization, heatwaves also lead to decreased academic and work productivity. Additionally, impaired cognitive functions (such as attention) increase the risk of accidents.

Here are the World Health Organization’s recommendations for protecting your body during heatwaves:

• Avoid outdoor activities during peak hours: From 10 AM to 4 PM, sunlight is at its strongest. Therefore, plan outdoor activities outside of this time frame;

• Maintain a suitable temperature indoors: Use air conditioning and a fan to keep the indoor temperature low. Use the fan only when temperatures are below 40 degrees Celsius. At higher temperatures, this device may only exacerbate the increase in body temperature. Keep windows closed during the day and use opaque blinds to prevent sunlight from entering. Open windows at night to reduce the ambient temperature. An effective and economical strategy to achieve lower ambient temperatures is to set the air conditioning to 27 degrees Celsius and use a fan at the same time;

• Stay hydrated: Drink water regularly throughout the day, such as a glass of water per hour, in small and frequent sips. Consume more fluids at the beach or while exercising;

• Regulate your body temperature: Wear loose, light-colored clothing and use cool cotton or other natural fabric bedding. Take cooler showers than usual and spray your skin with cold water when exposed to heat for extended periods;

• Seek Shade: In direct sunlight, temperatures can be 10-15 degrees Celsius higher. When you need to be outdoors during peak hours, look for shaded areas. Using an umbrella at the beach is also a good idea;

• Protect children and pets: Never leave children or pets in a vehicle. Avoid covering baby strollers with dry cloths to create shade, as this can cause overheating. Instead, use thin, damp fabrics and a portable fan. Dress children in loose clothing, wide-brimmed hats and sunglasses. Don’t forget sunscreen;

• Avoid exercising in extreme heat: Intense physical activity in high temperatures promotes dehydration, heat cramps and heatstroke. During heatwaves, make sure to exercise in well-ventilated environments or schedule outdoor workouts outside peak hours, and drink enough water;

• Monitor vulnerable individuals: It is important to monitor and care for loved ones over 65 years old and those with disabilities or chronic illnesses, such as cardiovascular and pulmonary conditions.

So, consider all protective measures against extreme heat to ensure you successfully avoid its consequences. Don’t hesitate to seek emergency medical care if you experience severe acute symptoms.