What are the signs of heat illness and what first aid is needed?

The SMA guidelines say to watch for heat-related illness whenever sport is played in the heat, whatever the risk level.

Heat exhaustion/syncope

• Feels: headache, dizziness, weakness, nausea, vomiting.
• Signs: fainting, increased heart rate, decreased blood pressure, core temperature usually below 40°C, and no brain symptoms.
• Immediate management: move to shade and cool, remove as much clothing as possible, remove protective equipment (e.g. helmets, pads), apply lots of water to the skin, give oral fluids, lie the person on their back with legs elevated, and watch for worsening.

Exertional heat stroke (a medical emergency)

• Brain symptoms including confusion and agitation, which can develop rapidly.
• Signs: confusion, unsteadiness, aggressive or irrational behaviour, altered level of consciousness, seizures or coma, increased heart and breathing rate, decreased blood pressure, core temperature usually above 40°C.
• Immediate management: ABC (airway, breathing and circulation), aggressively cool the body with ice and water (e.g. an ice or cold water bath), call an ambulance, and continue cooling during transfer to hospital: "Cool first, transfer second".

The SMA Sports Heat Tool page also says any collapse in hot conditions should be treated as potential heat stroke, and an ambulance called immediately.