Read time: 5 minutes 

Many of us love the sun — but usually when we are lounging by the pool with a cocktail in hand, not necessarily whilst working or when trying to get on with our busy everyday lives.

Heat related medical emergencies are common and can affect all ages. Many can be avoided if we take a little time to prepare for our day and know what to look out for.

If you are an Appointed First Aid Person or Trained First Aider at Work, take the time to pass this information on to your work colleagues and employers. In turn, it may help a family member or friend long after you have clocked off.

1. Heat Stroke

What is it? Heat stroke is the most serious heat related illness and should always be treated as a medical emergency. It occurs when the body's temperature rises to a dangerous level — above 40°C — and can no longer cool itself down. Unlike heat exhaustion, the person may stop sweating entirely as the body's cooling system fails. Without prompt treatment, heat stroke can cause damage to the brain, heart, kidneys, and muscles, and can be fatal.

Signs to look out for:

• High body temperature
• Hot, dry skin — or skin that is red and damp
• Rapid, strong pulse
• Confusion, disorientation, or unusual behaviour
• Slurred speech
• Loss of consciousness
• Seizures

How to treat it: Heat stroke requires immediate action. Call 999 straight away. While waiting for emergency services:

• Move the person to a cool, shaded area immediately
• Remove excess clothing
• Cool them down as quickly as possible — use cold, wet cloths, a fan, or ice packs wrapped in cloth applied to the neck, armpits, and groin
• Do not give them anything to eat or drink if they are confused or unconscious
• Monitor their breathing and be prepared to perform CPR if needed
• Stay with them until help arrives

Prevention:

• Stay hydrated throughout the day — don't wait until you feel thirsty
• Avoid strenuous activity during the hottest part of the day (usually 11am–3pm)
• Wear lightweight, breathable, light-coloured clothing
• Take regular breaks in cool or shaded areas
• Never leave anyone — including children, elderly people, or pets — in a parked car in warm weather

2. Dehydration

What is it? Dehydration occurs when the body loses more fluid than it takes in. In hot weather, we lose fluid rapidly through sweat — often without realising how much. Mild dehydration is very common and easy to overlook, but left untreated it can escalate quickly, particularly in children, older adults, and those with underlying health conditions.

Signs to look out for:

• Thirst — though by the time you feel thirsty, you are already mildly dehydrated
• Dark yellow or strong-smelling urine
• Dry mouth, lips, and eyes
• Headache and dizziness
• Fatigue and difficulty concentrating
• In severe cases — rapid heartbeat, rapid breathing, confusion, fainting

How to treat it:

• Encourage the person to drink water or an oral rehydration solution (available from pharmacies) in small, regular sips
• Move them to a cool environment and encourage rest
• Isotonic sports drinks can help replace lost salts and minerals after heavy sweating
• If the person is severely dehydrated, confused, or unable to keep fluids down, seek medical help immediately or call 999

Prevention:

• Drink regularly throughout the day — the NHS recommends 6–8 glasses of fluid daily, and more in hot weather or during physical activity
• Carry water with you and make it easily accessible
• Eat foods with high water content — fruit, salads, and vegetables all contribute to hydration
• Limit alcohol and caffeine, both of which increase fluid loss
• Check on children, elderly relatives, and vulnerable individuals regularly in hot weather — they may not recognise or communicate thirst

3. Heat Cramps

What is it? Heat cramps are painful muscle spasms that occur during or after physical activity in the heat. They are caused by the loss of salt and fluids through sweating, which disrupts the balance of electrolytes in the body. Although heat cramps are not usually dangerous on their own, they can be a warning sign that the body is struggling with the heat and may be on the way to heat exhaustion if not addressed.

Signs to look out for:

• Sudden, painful muscle spasms — most commonly in the legs, arms, or abdomen
• Heavy sweating
• Firm, hard muscles to the touch during the cramp

How to treat it:

• Stop activity and move to a cool place to rest
• Gently stretch and massage the affected muscle
• Drink water or an isotonic drink to replace lost fluids and electrolytes
• Eat a small salty snack if available — this helps restore the sodium lost through sweat
• Do not return to strenuous activity until the cramps have fully resolved and the person feels well
• Seek medical advice if cramps are severe, last longer than an hour, or the person has heart problems or is on a low-sodium diet

Prevention:

• Stay well hydrated before, during, and after physical activity
• Replace electrolytes lost through sweat — isotonic drinks, salty snacks, or oral rehydration sachets can all help
• Avoid vigorous exercise during the hottest parts of the day
• Build up gradually to physical activity in the heat — the body needs time to acclimatise

4. Sunburn

What is it? Sunburn is damage to the skin caused by overexposure to ultraviolet (UV) radiation from the sun. It can happen faster than most people realise — particularly on overcast days when UV levels remain high despite cloud cover, and it is not limited to holiday destinations. The UK summer sun is more than capable of causing significant burns, especially for those working outdoors for extended periods.

Signs to look out for:

• Red, hot, and painful skin — appearing within a few hours of sun exposure
• Skin that feels tight or begins to peel after 24–48 hours
• Blistering in more severe cases
• In serious cases — fever, chills, nausea, and fatigue (sometimes called sun poisoning)

How to treat it:

• Get out of the sun immediately and move to a cool, shaded area
• Cool the skin with cool (not cold) running water for at least 10–20 minutes
• Apply a gentle, fragrance-free after-sun lotion or aloe vera gel to soothe the skin — avoid butter, oils, or toothpaste, which trap heat and can worsen damage
• Drink plenty of water to rehydrate
• Take over-the-counter pain relief such as ibuprofen or paracetamol if needed
• Do not burst blisters — this increases the risk of infection
• If blisters are widespread, the person has a high temperature, or feels unwell beyond the skin, seek medical advice

Prevention:

• Apply broad-spectrum sunscreen of at least SPF 30 — and reapply every two hours, or more frequently if sweating or after contact with water
• Wear protective clothing — long sleeves, wide-brimmed hats, and UV-protective sunglasses
• Seek shade during peak UV hours (11am–3pm)
• Remember that UV rays reflect off water, sand, and concrete — shade alone is not always sufficient
• Check the UV index daily — even mild UV levels can cause damage with prolonged exposure

5. Aggravated Medical Conditions

What is it? Heat doesn't just create new medical emergencies — it significantly worsens existing ones. For people living with chronic or underlying health conditions, a heatwave can tip a well-managed condition into a crisis. This is one of the most overlooked heat risks, particularly in workplaces where colleagues may not be aware of each other's health backgrounds.

Conditions most commonly aggravated by heat include:

Heart conditions — Heat causes the heart to work harder to pump blood to the skin for cooling. For anyone with a pre-existing heart condition, this additional strain can trigger chest pain, palpitations, or cardiac events. Know where your nearest defibrillator is and ensure those around you know how to use it.

Respiratory conditions — Asthma and COPD can both worsen in hot, humid air. Hot air can irritate airways and trigger attacks. Ensure anyone with a respiratory condition has their inhaler or medication accessible at all times.

Diabetes — Heat affects blood sugar levels and can interfere with insulin absorption. Dehydration, which is more common in heat, can also cause dangerous spikes in blood sugar. People with diabetes should monitor their levels more frequently in hot weather and keep medication stored correctly — many insulins must not be left in direct sunlight or high temperatures.

Epilepsy — Overheating, dehydration, and disturbed sleep — all common in a heatwave — are known triggers for seizures. Those with epilepsy should take extra care to stay cool, hydrated, and rested.

Mental health conditions — Some psychiatric medications affect the body's ability to regulate temperature or increase sensitivity to heat. The psychological impact of sustained heat — disrupted sleep, discomfort, and reduced ability to cope — can also worsen anxiety, low mood, and other conditions.

How to help:

• If someone with a known condition appears unwell in the heat, take it seriously and act early — do not wait for symptoms to worsen
• Encourage them to follow their own medical guidance and contact their GP or specialist if they are unsure
• Call 999 if symptoms are severe, the person loses consciousness, or you are in any doubt
• As a First Aider, be aware of the medications and conditions of those around you where possible — this information can be critical in an emergency

Prevention:

• Encourage anyone with an underlying condition to speak to their GP before a heatwave about how to manage their health in the heat
• Ensure medications are stored correctly and not left in hot cars, direct sunlight, or warm rooms
• Check in regularly with vulnerable colleagues, friends, and family during periods of prolonged heat
• Know your colleagues — a brief, compassionate conversation about how someone is coping can make all the difference

A Final Word

Heat related emergencies are largely preventable — and when they do happen, a calm and informed response can save lives.

If you are a First Aider at Work, you already have the skills to make a real difference. Share what you know. Speak up when you notice someone struggling. And encourage the people around you to prepare before the heat becomes a problem.

Not yet trained? At Experience Medical Training we offer First Aid at Work courses across Nottinghamshire and the East Midlands — practical, engaging training delivered by an instructor with real frontline ambulance and fire service experience. We also offer Mental Health First Aid and Wellbeing at Work programmes for employers who want to look after the whole person, not just the physical.

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Written by Experience Medical Training | Nottinghamshire First Aid at Work | Mental Health First Aid | Wellbeing at Work