Heat Related Health Problems

Overview

Heat-related health problems happen when your body gets too hot and cannot cool itself down properly. Your body normally cools itself by sweating and by sending more blood to the skin. When it is very hot, humid, or you are working hard in the heat, this cooling system can struggle. Problems range from mild ones like heat rash, swollen ankles and muscle cramps, to heat exhaustion (feeling very unwell from the heat), and in the most serious cases heatstroke. Heatstroke is a medical emergency and needs help straight away.

Yes. Heat-related illness is very common during hot spells and heatwaves. Most cases are mild and get better with simple cooling and fluids, but the number of people needing medical help rises quickly whenever the weather turns very hot.

Anyone can be affected, especially people who work or exercise outdoors, or who live in flats that get very hot. Some people are at much higher risk: babies and children under 5, adults over 65 (especially those living alone), people with heart, lung, kidney or circulation problems, people with diabetes, people with dementia or limited mobility, people who are pregnant, people who are homeless, and people taking some types of medicine that affect sweating or fluid balance.

Symptoms

Common symptoms

• Heavy sweating and feeling very thirsty
• Skin that feels cold, clammy or pale, sometimes with goosebumps
• Muscle cramps, often in the legs, arms or tummy
• Feeling dizzy or light-headed, especially when standing up
• Headache and feeling sick or actually being sick
• Feeling weak, tired or lacking energy
• A fast heartbeat and quick, shallow breathing
• A prickly, itchy red rash in skin creases (heat rash)
• Swollen ankles, feet or hands (heat swelling)
• Feeling faint or actually fainting

Symptoms in children

• Being unusually sleepy, floppy or hard to wake
• Fussiness, crying more than usual, or irritability
• Fewer wet nappies or weeing much less than usual
• Refusing feeds or drinks, or being sick
• Hot, red skin, or sunburn
• Fast breathing or a racing heartbeat
• Dry mouth, sunken eyes, or no tears when crying

Symptoms in older adults

• Confusion or new forgetfulness — this can be the first sign
• Not feeling thirsty even when the body needs fluid
• Feeling weak, unsteady on the feet, or falling
• Dizziness when getting up from a chair or bed
• Sweating much less than you would expect
• Dry mouth, dark urine, or passing much less urine
• Worsening of existing heart or breathing problems

Causes

Main causes

• Being in very hot weather, especially during a heatwave
• High humidity, which stops sweat evaporating and cooling you down
• Physical activity or heavy work in the heat, such as exercise, gardening or building work
• Not drinking enough, so the body has less fluid to make sweat
• Sitting in direct sun, or being in a hot, stuffy room or car with no airflow
• Wearing too many clothes or heavy protective clothing in the heat
• Being in a parked car or a room with closed windows on a hot day

Risk factors

• Being a baby or young child — young bodies heat up faster and cool down more slowly
• Being over 65, especially if you live alone or have limited mobility
• Heart, lung, kidney or circulation conditions, and diabetes
• Dementia, confusion or memory problems — you may not notice the heat or remember to drink
• Being pregnant
• Being overweight, or having a high body temperature from a fever or infection
• Some medicines, such as water tablets (diuretics), some antidepressants, some antihistamines and some blood pressure medicines — ask your pharmacist whether yours affect how you handle heat
• Drinking too much alcohol, which dehydrates you
• Working outdoors, doing sport, or being homeless and living outside
• Living in a top-floor flat or a home that is hard to keep cool
• Having had heat illness before

When to see a doctor

See a doctor urgently if:

• Heat exhaustion that is not getting better after 30 minutes of cooling down and sipping fluids
• Vomiting, or being unable to keep fluids down
• Confusion, drowsiness or odd behaviour in a hot person — get emergency help first, then follow up
• Chest pain, severe breathlessness, or a very fast or irregular heartbeat
• Any baby or young child who is hot, sleepy, feeding poorly or has fewer wet nappies

Book a routine appointment if:

• You keep getting heat rash, swelling or cramps whenever it is warm
• You want to check whether any of your medicines make you more sensitive to heat
• You have a long-term health condition and want advice on staying safe in hot weather
• You care for someone older or unwell and want a plan for heatwaves

Diagnosis

For most mild heat problems, no tests are needed. A doctor or nurse will usually work out what is going on by talking to you about the heat, your symptoms, your medicines and your health history, then checking your temperature, pulse, blood pressure and breathing. They will also check how hydrated you are, for example by looking at your mouth, skin and urine.

Tests that may be done

• Temperature, pulse, blood pressure and breathing rate
• A urine test to check how well hydrated you are
• Blood tests to check salt levels and kidney function — usually only in more serious cases
• An ECG (heart tracing) if your heartbeat is fast or irregular
• Checks for other causes of your symptoms, such as an infection

What to expect at your appointment

In most cases the appointment is quick and simple, and you can go home once you feel better. If you are more unwell, or if you are a baby or an older adult, you may be watched for a while to make sure your temperature comes down and you are drinking normally. If heatstroke is suspected, you will be taken to hospital straight away for cooling and monitoring.

Treatment

The first and most important treatment for any heat-related problem is the same: get out of the heat, cool the body down, and replace lost fluids. Everything else — whether at home or in hospital — supports that. The faster someone is cooled, the better the outcome, especially if heatstroke is possible.

Self-care at home

• Move to a cool, shaded or air-conditioned place as soon as you feel unwell, and lie down with your feet slightly raised
• Loosen or remove unnecessary clothing
• Sip water, or a rehydration (oral rehydration) drink from a pharmacy — take small, frequent sips rather than large gulps
• Cool your skin with a cool shower or bath, a sponge or flannel with cool water, or a spray bottle of water
• Use a fan and open windows to get air moving, and put cool packs or damp cloths on the neck, armpits and groin where blood vessels are close to the skin
• Rest and avoid any strenuous activity for the rest of the day
• Keep checking how you feel — if you are not clearly better within about 30 minutes, get medical advice
• For heat rash, keep the skin cool and dry, wear loose cotton clothing, and avoid thick creams that block the skin
• For swollen ankles, sit with your feet raised and avoid standing for long periods
• Ask someone to stay with you and keep an eye on you until you feel fully well

Medical treatments

In mild cases, treatment is simply the cooling and fluids described above, with advice about avoiding heat. If you are more unwell, a healthcare team may give fluids through a drip (intravenously) to rehydrate you quickly, monitor your temperature, heart rate and blood pressure, and use active cooling methods such as cool air, water sprays and cooling blankets. Blood tests may be repeated to check your salt levels and kidney function. Anyone with suspected heatstroke needs hospital care and rapid cooling — this is the treatment that matters most. Your care team will also review your regular medicines, as some may need adjusting during hot weather.

When is surgery considered?

Surgery is not used to treat heat-related health problems. In rare cases where heatstroke has caused damage to an organ, other specialist teams may become involved, but this is not part of usual care.

Living with this condition

During hot weather, adjust your routine rather than pushing through. Plan the jobs that need effort — shopping, cleaning, gardening — for the coolest parts of the day, and keep the hottest rooms shaded and ventilated. Keep water where you can see it and sip it regularly, even before you feel thirsty. If you know you cope badly in the heat, tell family, friends or neighbours so they can check on you.

Lifestyle tips

• Keep windows shaded with curtains or blinds during the day, and open windows at night when it is cooler
• Have cool showers or baths, and use a damp cloth on the back of your neck
• Wear loose, light-coloured, breathable clothing and a wide-brimmed hat when outside
• Avoid alcohol and drinks with a lot of caffeine in very hot weather, as they can make dehydration worse
• Avoid going out in the strongest sun, usually between 11am and 3pm
• Never leave anyone — especially a baby, a child, an older person or a pet — in a parked car, even for a minute
• Check on neighbours, relatives and friends who live alone or are unwell
• Keep a bottle of water with you when travelling or exercising

Diet and exercise

Eat light, regular meals and include foods with a high water content, such as fruit, salad and vegetables. Drink regularly throughout the day — water is best, and rehydration drinks can help if you have been sweating a lot. If you exercise, do it in the early morning or evening, drink before, during and after, and stop straight away if you feel dizzy, sick or unusually tired. Build up slowly if you are not used to exercising in the heat.

Mental health and emotional wellbeing

Hot weather can affect mood and sleep. Being too hot at night makes it harder to rest, which can leave you irritable, anxious or low the next day. Some mental health conditions and some medicines can also change how your body handles heat. If you feel overwhelmed, tell someone you trust and speak to your GP or pharmacist — and if your mental health feels at crisis point, contact your local crisis line or emergency services straight away.

Prevention

Yes, mostly. Heat-related illness is largely preventable by planning ahead, drinking regularly, keeping your home and body cool, and knowing the warning signs. The key habit is to act early — cool down and drink at the first hint of feeling too hot, rather than waiting to see if it passes.

Vaccines

There is no vaccine for heat-related health problems. Staying cool, hydrated and informed is the protection.

Screening programmes

There is no screening test for heat illness. However, it is worth asking your GP or pharmacist to review your medicines before summer, especially water tablets, blood pressure medicines and medicines that affect sweating, as the dose may need adjusting in hot weather. Never change your medicines yourself — always ask first.

Complications

If left untreated

• Heat exhaustion getting worse and progressing to heatstroke
• Heatstroke, which can cause damage to the brain, heart, kidneys and muscles
• Dangerous dehydration, with low blood pressure and fainting
• Kidney injury from dehydration and muscle breakdown
• Falls and injuries, especially in older adults who become dizzy
• Worsening of existing heart or lung conditions
• In the most serious, untreated cases, heatstroke can be life-threatening

Long-term outlook

The outlook is good for most people. Heat cramps, heat rash and mild heat exhaustion usually settle within hours to a day with rest, cooling and fluids, and leave no lasting effects. Heatstroke is serious, but with quick cooling and medical care most people recover — and knowing the signs means you or someone else can act fast. If you have had heat illness before, take extra care next time, as you may be more sensitive to heat.

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