Heatstroke symptoms, how to spot them and what to do next

Before identifying the symptoms, it is important to understand what happens in the body during excessive sun exposure.

Definition

Heatstroke is the body’s reaction to prolonged, direct exposure to the sun, particularly when the head and neck are unprotected. It results in an elevated body temperature, accompanied by various symptoms linked to a less effective thermal regulation system.

Contrary to popular belief, heatstroke does not depend solely on the outside temperature. Direct exposure to sunlight, even in moderately warm weather, can be enough to disrupt the body’s balance, especially in cases of dehydration, fatigue, or physical exertion.

In practical terms, the body struggles to dissipate the accumulated heat. This imbalance leads to gradual overheating, which triggers the first warning signs.

What is the difference between heat exhaustion and heatstroke?

Sunstroke is most often a condition linked to direct sun exposure. It manifests as uncomfortable symptoms, which are generally reversible with appropriate measures such as rest, cooling, and hydration.

Heatstroke, on the other hand, is a medical emergency. It involves generalised central hyperthermia resulting from an acute failure of the body's temperature regulation system. Body temperature can exceed 40°C, accompanied by significant neurological symptoms. It can occur without direct sun exposure, particularly during extreme heat or intense physical exertion.

Without proper treatment, heat exhaustion can, in some cases, progress to heatstroke.

Dehydration: Symptoms

Dehydration frequently accompanies heatstroke and can exacerbate its symptoms. It involves a loss of water and electrolytes, often linked to heavy sweating. It can manifest as:

• Intense thirst

• A dry mouth

• Decreased urine output

• Unusual fatigue

• Dizziness.

In some cases, muscle cramps or a feeling of malaise may occur. This fluid loss further weakens the body and reduces its ability to cope with heat.

The signs of heatstroke can appear quickly, sometimes within an hour of exposure. Their severity varies depending on the individual and the conditions of exposure.

Headaches

They are among the first signs. Often diffuse or throbbing, they indicate heat-induced dilation of blood vessels. This sensation may be accompanied by sensitivity to light and a feeling of heaviness in the head.

Nausea and vomiting

The digestive system frequently reacts to body overheating. Nausea may occur, sometimes followed by vomiting. These symptoms contribute to fluid loss and require increased vigilance.

Dizziness and lightheadedness

These symptoms result from a drop in blood pressure and impaired blood circulation. A feeling of instability or dizziness should be a warning sign, especially when standing.

Intense fatigue

The body expends a great deal of energy trying to maintain a stable temperature. This exertion results in unusual fatigue, sometimes accompanied by difficulty concentrating.

A sensation of heat and warm skin

The skin may become hot, dry, and sometimes red. Unlike simple heat-related sweating, the skin may lose its ability to cool down effectively.

An increase in body temperature

Mild hyperthermia is common. If the temperature becomes high or persistent, it requires special attention.

Digestive issues

Abdominal pain or diarrhoea may occur, often linked to dehydration and electrolyte imbalances.

Neurological signs

In more severe cases, symptoms such as confusion, irritability, disorientation, or sometimes chills may occur. These symptoms must be taken seriously.

The different degrees of severity of heatstroke

Heatstroke can present in several forms, ranging from mild discomfort to a more serious condition. Identifying the severity level allows you to quickly determine the appropriate course of action.

The more severe the symptoms, the faster treatment must be provided. Worsening symptoms can lead to heatstroke.

The most vulnerable populations react more quickly and intensely to heat. Paying close attention allows for earlier detection of warning signs and immediate action.

Children

Children are more sensitive to heat. Their thermoregulatory system is still immature, which limits their ability to maintain a stable body temperature.

The signs may be less specific than in adults and include:

• Unusual irritability

• Restlessness or, conversely, drowsiness

• Refusal to drink

• Unusual crying

In infants, certain signs should raise immediate concern, including a lack of tears when crying, decreased urination, or a slightly sunken fontanelle. The challenge lies in the fact that the child expresses their discomfort poorly or not at all. Careful observation of their behavior therefore remains essential, particularly after sun exposure.

Vulnerable or elderly individuals

As we age, several physiological mechanisms change. The sensation of thirst becomes less reliable, while the body’s ability to regulate its temperature gradually decreases. Certain factors can exacerbate this sensitivity, such as medication use, chronic health conditions, or inadequate hydration. Symptoms may appear subtly at first but can quickly progress to a more serious condition. Unusual fatigue, mild confusion, or decreased alertness should prompt caution. During periods of extreme heat, regular monitoring and adequate hydration remain essential to minimise risks.

If you suspect heatstroke, it is important to act quickly with simple, appropriate steps.

• Immediately move to the shade or a cool place, away from the sun and heat

• Lie down and rest to minimise exertion and allow your body to recover

• Rehydrate gradually, by drinking water in small, regular amounts, without waiting until you feel thirsty

• Gently cool your body, for example by applying cool compresses to your neck, forehead, and wrists

• Adjust your clothing, opting for light, loose-fitting, and breathable garments.

If symptoms persist, worsen, or are accompanied by symptoms such as confusion, repeated vomiting, or severe weakness, consult a healthcare professional immediately. If severe symptoms are present, prompt medical attention is essential.

To reduce the risk of heatstroke, prevention relies on a few simple steps to follow, particularly during periods of extreme heat.

1. Stay hydrated regularly throughout the day: Don’t wait until you feel thirsty; choose water and limit alcoholic or overly sugary drinks

2. Avoid prolonged exposure during the hottest hours: Generally between 11 a.m. and 4 p.m., when solar radiation is most intense

3. Protect your head and neck: Wear a hat, cap, or other head covering

4. Choose lightweight, loose-fitting, light-colored clothing: It promotes air circulation and limits heat buildup

5. Take regular breaks in the shade: This allows your body to cool down gradually

6. Cool down your body several times a day: Wet the back of your neck, your face, or your arms

Adjust your activity level during hot weather: reduce the intensity of physical exertion and focus on the coolest times of the day to minimise risks.

Good to know: Sunscreen protects the skin from UV rays and helps prevent sunburn. However, it does not directly protect against heatstroke, which results from the body overheating due to prolonged exposure to heat and sunlight. It therefore remains an essential step for skin care, but must be supplemented by other measures such as hydration, shade, and head protection.

Heatstroke is one of the most well-known bodily reactions to excessive heat exposure. However, other conditions can arise in this context, with similar mechanisms but varying intensities.

• Heat-related cramps, often associated with electrolyte loss due to heavy sweating

• Heat exhaustion, which manifests as intense fatigue, general weakness, and profuse sweating

• Heatstroke, the most severe form, characterized by a marked rise in body temperature and neurological symptoms.

These conditions have one thing in common: the body’s difficulty in effectively regulating its temperature and maintaining its internal balance in the face of heat.

Certain situations require special vigilance, particularly during intense physical activity in extreme heat, when consuming alcohol or beverages that promote dehydration, when taking certain medications, or during prolonged sun exposure without protection. Pay attention to your body’s signals and consult a healthcare professional if you experience unusual, persistent, or worsening symptoms.

During hot weather, your body may need to be hydrated even before you feel thirsty. Get into the habit of drinking very regularly, in small sips, to maintain proper hydration and better cope with heat waves.

Passionate about plants and their properties, she has been working in the world of natural beauty and aromatherapy for over 10 years, after starting her career with a perfumer. Lucie supports ethical and committed brands in their development strategy, product formulation and the expert advice they give their customers. She has worked with our Aroma-Zone teams on several books, including "Le grand guide de l'Aromathérapie et des cosmétiques naturels". At the same time, she has been training for years in aromatherapy, herbalism and the distillation of essential oils, while supporting the work of French plant growers.