As the United Kingdom experiences its hottest days of the year, medical professionals are emphasizing the critical need to recognize the signs of heat stroke, a potentially fatal condition that can develop rapidly. Heat stroke occurs when the body's core temperature rises to dangerous levels and it can no longer cool itself, leading to severe consequences including seizures, organ failure, coma, and death if not treated urgently.
The current heatwave, with temperatures forecast to reach the high 30s Celsius in parts of England and Wales, has prompted the Met Office to issue extreme heat warnings. Health officials have cautioned that the extreme temperatures pose risks not only to vulnerable populations such as the elderly but also to healthy adults and children.
Last summer, the UK Health Security Agency (UKHSA) recorded an estimated 1,504 heat-associated deaths across England during five distinct heat episodes. Dr. Ann Nainan, a general practitioner specializing in urgent care, stated that heat stroke is a life-threatening emergency requiring immediate medical intervention and that recognizing early symptoms is crucial for taking timely corrective action.
Heat Exhaustion vs. Heat Stroke
There are two primary forms of heat stroke: one resulting from intense physical activity in extreme heat, and another from gradual exposure to high temperatures. Heat exhaustion often precedes heat stroke and requires prompt treatment to prevent progression. Symptoms of heat exhaustion include a high body temperature, intense thirst, confusion, irritability, headaches, nausea, dizziness, excessive sweating, pale or clammy skin, and muscle cramps.
To mitigate heat exhaustion, the NHS recommends moving the affected individual to a cooler environment, removing unnecessary clothing, and encouraging fluid intake, preferably with rehydration drinks containing electrolytes. Cooling the skin through methods like spraying with cool water, applying ice packs, or using damp cloths is also advised. If symptoms do not improve within 30 minutes, emergency medical assistance should be sought, as the condition may have advanced to heat stroke.
Timeline of Heat Effects
Experts note that even brief exposure to extreme heat can impact the body. Within five to 10 minutes of exposure to temperatures above 35C, the body begins to work harder to maintain its normal temperature of approximately 37.3C. Heart rate and sweat production increase, which can lead to dehydration, especially with direct sun exposure or insufficient fluid intake. Simple preventative measures like wearing loose clothing, applying sunscreen, and drinking water regularly can help.
After approximately 10 minutes without preventative actions, discomfort intensifies, sweating increases, and dehydration may begin, potentially causing headaches. A few minutes in the shade and consuming cool water can alleviate these early signs.
Between 10 and 40 minutes of exposure without precautions, the body expends significant energy attempting to cool down. Thirst becomes more pronounced, and skin may burn if sunscreen has not been applied. By about 40 minutes, individuals may start experiencing early signs of heat exhaustion, including cramps, headaches, nausea, and dizziness, due to electrolyte imbalance. Without intervention, the risk of developing heat stroke increases.
After one hour of exposure to extreme heat, the body's temperature can rise to 38.5C, a state known as hyperthermia, potentially leading to heat exhaustion. Dr. Rowley Cottingham, a consultant in emergency medicine, noted that people may feel intensely tired and desire to cease all activity. In such situations, seeking shade or shelter, drenching clothing with water, and sipping water are recommended. Consuming electrolyte-rich foods like bananas and watermelon can also help. If symptoms persist or worsen, medical advice is necessary.
Progression to Heat Stroke
If preventative measures are not taken or are ineffective, the body can enter a state of heat stroke between 90 minutes and two hours of prolonged exposure. The body's temperature may reach 40C, leading to malfunction of the brain, heart, and liver. Dr. Cottingham described this state as incredibly dangerous and rapidly fatal, comparing it to proteins being damaged by heat. Confusion is an early neurological symptom, often due to brain swelling. Impaired balance and coordination, hot and dry skin, a rapid heartbeat, dizziness, weakness, nerve dysfunction, and fainting can follow. In severe cases, heat stroke can result in loss of consciousness, seizures, coma, and death without urgent medical treatment.