The human body requires a relatively stable internal temperature for physiologic processes to be properly carried out. Generally, when you are exposed to hot environmental conditions, your body sweats as a cooling mechanism. However, extreme heat can sometimes overwhelm your body such that sweating does not provide adequate cooling, especially if you are also exerting yourself with exercise. According to the Centers for Disease Control and Prevention, there are other factors that hinder your body's ability to regulate temperature and they include old age, youth, obesity, fever, dehydration, heart disease, mental illness, poor circulation, sunburn, prescription drug use and alcohol use. The presence of a headache can be a symptom of a heat-related illness such as heat exhaustion or heat stroke.
Heat Exhaustion
Headache while exerting yourself in the heat may be a symptom of heat exhaustion. Heat exhaustion can occur after prolonged strenuous activity with inadequate water intake or when large volumes of sweat are replaced with fluids that don't contain enough salt. Symptoms of heat exhaustion include nausea, vomiting, general discomfort, muscle pain, hyperventilation, thirst, weakness, headache, dizziness, fatigue, anxiety, numbness and tingling, and altered mental status. When these symptoms persist for a prolonged period and the individual has an increased heart rate and core body temperature higher than 37.8 degrees Celsius, the diagnosis of heat exhaustion is made. Treatment of heat exhaustion includes moving the individual to a cool environment, providing 1 to 2 liters of hydration over two to four hours, giving oral salt replenishment and active cooling measures such as fanning.
(Reference 2,3)
Heat Stroke
If let untreated, heat exhaustion can lead to heat stroke, which is a medical emergency. A throbbing headache can be one symptom of impending heat stroke. Heat stroke is characterized by brain dysfunction and core body temperature higher than 40 degrees Celsius. Other symptoms include dizziness, weakness, emotional lability, nausea and vomiting, diarrhea, confusion, delirium, blurred vision, convulsions, collapse, and unconsciousness. Heat stroke can lead to heart attack if not promptly treated. Treatment goals are to rapidly reduce the core body temperature and to manage fluid status. Methods are taken to decrease shivering in these patients as this can cause bodily heat production.
Other Heat-Related Illnesses
Other heat-related illnesses are heat cramps, heat collapse and heat rash. Heat cramps are slow, painful muscle contractions that occur due to disruptions in normal fluid and electrolyte balance. This is particularly true when sweat losses are replaced with pure water causing low blood sodium levels. The individual should be moved to a cool environment and given an oral solution of 4 tsp. of salt per gallon of water to replace both salt and water. Heat collapse may occur during or immediately after exercise in the heat and is caused by low blood volume and dilation of blood vessels to accommodate the hot conditions. Treatment includes rest and fluid and electrolyte replenishment. Heat rash is a red cluster of pimples or small blisters that develop as the skin becomes irritated by continuous sweating. It is most common in kids. It can be managed by keeping the area dry.
Benign Exertional Headache
Headache during exertion may also be a benign condition and unrelated to the environmental temperature. These headaches occur with exercise and often have a throbbing quality, resembling a migraine. The symptoms can last up to 24 hours after exercise. The non-steroidal anti-inflammatory medications are often effective in treatment of exertional headaches, particularly indomethacin. Other medications include those used to treat migraines such as ergotamine, dihydroergotamine or methysergide.
References
- Centers for Disease Control and Prevention: Extreme Heat FAQs
- University of Maryland Medical Center: Heat Exhaustion
- "Current Medical Diagnosis and Treatment, Ch. 37"; Dr. Jacqueline A. Nemer, FACEP; 2011
- "Harrison's Principles of Internal Medicine, Ch. 15"; Dr. Peter J. Goadsby, Ph.D., DSc, Dr. Neil H. Raskin; 2008
