Heat Illness Prevention & Sun Safety

 Heat-Related Illness Prevention

Last Updated: April 10, 2024


Heat illnesses occur year-round in military training environments and increase significantly in warmer weather. 

​What are heat illnesses? 

In the military, heat illnesses are typically associated with warmer weather and physical activity so are referred to as Exertional Heat Illnesses (EHI), a range of conditions that can occur when the body overheats. Failure to prevent milder conditions from progressing can result in more serious heat casualties, including death. EHI range from dehydration and mild heat cramps, to a more serious medical condition called heat exhaustion, to the life-threatening medical emergency heat stroke

In addition is hyponatremia, a possibly fatal condition when too much water consumption causes an imbalance to the body’s chemistry.​ 

​News article: Service members need to remember signs, symptoms of heat illness as weather warmsExternal Link (Mar 2023)​ 

Heat Illness Prevention: What can you do?

See the Milita​​ry Health Illness Prevention Brochure (2023) 

Know the primary risk factors for heat illness: 

  • Environment: high temperature, high humidity, wind, solar load, repeated hot/humid days
  • Mission: high exertion/intensity, heavy loads/gear, repeated strenuous days
  • Individual: acclimatization status, poor fitness (2 mile run >16 minutes for males, >19 minutes for females), BMI >26, age <20 or >40, poor hydration/nutrition status, minor illness (fever, skin rash, sunburn, or poison ivy), medication (antihistamines, decongestants, some blood pressure medications, some psychiatric drugs), alcohol use in the past 24 hours, sleep deprived, highly motivated 

Actions to take: 

Service Members:

  • ​Know the heat category (WBGT) at your location and be aware as it changes over time. 
  • Wear clothing level appropriate for the Risk Category; include use of wide brimmed hat to avoid high sun exposure
  • Stay hydrated but avoid over-hydration. 
    • ​​Adhere to fluid replacement and work-rest guidelines (see 2023 brochure) 
    • Do not exceed 1 quart per hour (qt/h) under most conditions.
    • Under certain very strenuous conditions a maximum of 1½ qts/h or 12 qts/day may be advised.
    • As a means of self-check, urine should in general be pale yellow to clear. (This is not always a guarantee however as individual conditions may affect)
    • Do not empty canteens to lighten your load.
    • Avoid use of alcohol, energy drinks, and supplements.
      • ​​Salt tablets are not recommended. 
      • Flavored drink powders can be used to encourage fluid consumption
  • ​​​​Inform your leader and battle buddy if you have had a prior EHI or have specific EHI risk factors. 
  • Use beads or knots to track how much fluid you are consuming (allowing others to see your fluid consumption can be lifesaving and may be the only immediate way to differentiate heat stroke and hyponatremia (too much fluid consumption).​ 



  • ​​Use risk management guidelines when planning for training in the heat 
  • Monitor WBGT and adjust outdoor activity levels, duration, location and time of day as needed 
  • Find ways to reduce heat stress in individuals: 
    • ​​Conduct training and other strenuous activities in the early morning or evening when possible. 
    • Plan for rapid cooling (Arm Immersion Cooling System (AICS) stations, ice sheets) at training locations
    • Encourage consistent food and fluid intake, but watch for excessive fluid intake 
  • ​Ensure personnel are trained on heat illness prevention, recognition, and basic treatment 
  • Know the current profile status of Service members - Proper profiling can minimize recurrent heat illness in susceptible personnel (AR 40-501) 
  • Service members with previous heat illness should be monitored closely for over-hydration and signs and symptoms of repeat heat illness​


  • Initial management and most effective intervention in suspected heat illness is rapid cooling
  • Verify sodium level prior to and during rehydration efforts
  • Review medical history and document heat-related conditions - Proper profiling can minimize recurrent heat illness in susceptible personnel (AR 40-501) 
  • Notify preventive medicine to report cases of heat illness (heat exhaustion and heat stroke are RMEs to be reported to the Disease Reporting System internet​)