Heat Cramps: symptoms include muscle spasm and fatigue. This is relieved by rest, stretching and taking on board cold fluids
Heat Exhaustion: the body primarily tries to lose heat by sweating profusely. It can make the casualty feel faint, dizzy, lack of coordination. Treatment includes cooling the casualty using ice packs to the armpit and groin areas, elevating the legs and monitoring AVPU
Heat Stroke: this is a medical emergency. The body cannot afford to lose any further fluid and so stops sweating and slowly begins to cook itself. This is a 999 emergency and you should be prepared to resuscitate your casualty.