As we arrive at the warmer summer months of July and August, we are all reminded of how hot and humid it can become here in Iowa. We need to be reminded and aware of heat-related illnesses. Heat-related illnesses (AKA heat intolerance, heat stroke) are common and relatively easy to avoid. There are factors which predispose to heat intolerance, these include, among others, low level of physical fitness, lack of acclimatization, obesity, use of alcohol prior to activity, and certain medications such as stimulants. Heat exhaustion is defined as the inability to maintain adequate cardiac output due to strenuous physical exercise and environmental heat stress. Dehydration may or not be present with heat exhaustion. This may progress to heat injury, defined by a core body temperature greater than 104 F and organ injuries such as kidney damage. This again may progress to exertional heatstroke (EHS) which is a life-threatening illness. We need to be careful in the heat. Dress appropriately, limit activities, stay well hydrated, and most importantly, get out of the heat when symptoms arise. If symptoms become more severe, including confusion, vomiting, or other concerning symptoms, these people should be evaluated in the emergency department.