Heat exhaustion or heat stroke? Signs and first aid on the worksite
Heat illness can go from a headache to an emergency quickly. The signs to watch for, and what to do before the ambulance arrives.
Heat illness rarely arrives without warning. Most cases start with small signs that a buddy or supervisor can spot, if they know what to look for. Act early and a worker usually recovers after rest, water and cooling. Miss the signs and it can turn into heat stroke, a medical emergency.
The early warning signs
MOM lists early signs of heat-related illness that include:
- weakness, dizziness or unusual tiredness
- headache or blurred vision
- intense thirst
- nausea, vomiting or diarrhoea
- muscle cramps
- breathlessness or a racing heart
- tingling or numbness
Any of these on a hot day means stop work and cool down. Do not let the worker "push through to the break".
Heat exhaustion vs heat stroke
| Heat exhaustion | Heat stroke | |
|---|---|---|
| Alertness | Awake and able to talk sensibly | Confused, disoriented, slurred speech, or unconscious |
| Body | Heavy sweating, pale or clammy skin, cramps | Very high body temperature (core above 40°C), may have seizures |
| Urgency | Needs rest and cooling now | Emergency: call 995 |
If you are not sure which it is, treat it as heat stroke.
First aid: what to do
If the worker is alert
- Stop work and move them to a cool, shaded or air-conditioned place.
- Remove excess clothing, such as helmets, vests and outer layers.
- Cool them actively: cold water, ice packs, water spray or wet towels, especially on the neck, armpits and groin.
- Give cool water to drink in small sips if they can swallow.
- Stay with them and watch for any change. If they get worse or do not improve, call 995.
If the worker is confused, collapses or is unconscious
- Call 995 immediately.
- Start cooling straight away while you wait, with cold water, ice packs or water spray. Every minute counts.
- Do not give anything to drink if they are not fully awake.
- Report the incident through your site's procedure.
Why the emergency cooling kit matters
From 1 December 2026, MOM requires cold water, ice packs or water spray on standby for emergencies. MOM's guidance is to have enough to actively cool at least one affected worker for several minutes before emergency services arrive.
Instant chemical cold packs can help, but they do not replace these. They are small and do not stay cold for long.
A few practical points:
- Keep the kit at each work area, not in the site office.
- Check every morning that ice packs are frozen and water is cold.
- Make sure every supervisor knows where the kit is.
Prevention is the real first aid
Most cases are preventable with the basics: regular water, rest breaks that grow with the WBGT, a buddy system, and acclimatisation for new and returning workers.
How HeatAware helps
Every HeatAware kit includes an emergency cooling kit for each work station, tagged and checked, plus training so workers know the signs. Size your kit to see what your site needs.
General guidance based on MOM's FAQs on Heat Stress Measures for Outdoor Work. This is not medical advice. In an emergency, call 995.