Heat Cramps

  • Medical Author:
    Benjamin Wedro, MD, FACEP, FAAEM

    Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Heat-Related Illness Symptoms

Symptoms of heat-related illness or hyperthermia vary according to the specific type of illness.

  • Heat stroke is the most severe form of hyperthermia.
  • Heat exhaustion is a less severe form of hyperthermia, with symptoms like weakness, nausea, vomiting, headache, muscle cramps, and profuse sweating.
  • Heat cramps symptoms include involuntary spasms of large muscle groups
  • Heat syncope symptoms include fainting or lightheadedness.
  • Heat rash symptoms are red bumps on the skin with a feeling of "itchy" or "prickly" feeling of the skin.

Heat cramps facts

  • Heat cramps are intermittent, involuntary spasms of larger muscles that occur in an individual who is physically active in hot weather.
  • Heat cramps, heat exhaustion, and heat stroke are collectively known as heat-related illness. Heat cramps are the least serious of the three, but still may be very painful and alarming.
  • Heat cramps usually affect the major muscles that are being stressed in a hot environment.
  • Individuals at risk for heat cramps include those who work, exercise, or are active in a hot environment.
  • Individuals with impaired temperature control mechanisms, such as infants, young children, and the elderly, are also at a greater risk of heat cramps.
  • Heat cramps are the earliest symptoms of a heat-related illness.
  • Symptoms of heat cramps include profuse sweating with involuntary spasms of the large muscles in the body.
  • Heat cramps also may be a symptom of heat exhaustion.
  • The diagnosis of heat cramps is usually made by reviewing the patient history and identifying the muscle groups that are involuntarily in spasm.
  • Treatment of heat cramps include rest, cooling the body, hydration, and stretching the muscles that are cramping.
  • Heat cramps can be prevented by avoiding exercise or work during the heat of the day, drinking plenty of fluids, and resting in cool or shaded areas when possible.

What are heat cramps?

Heat cramps are the intermittent, involuntary spasm of muscles that occur in an individual who is physically active (for example, working or exercising) in hot or humid weather. They are often associated with dehydration. Heat cramps usually affect the major muscles that are being stressed in the hot environment. Most often these are the thigh and leg (quadriceps, hamstrings, gastrocnemius), the core muscles (abdominal wall and back) and the arm muscles (biceps, triceps).

Heat cramps can also occur after the activity has been completed. For example, construction workers or roofers can develop cramps a few hours after their work shift is over.

Medically Reviewed by a Doctor on 9/2/2016

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