Written by Dr Zamiel Hussain, Lead GP and Founder of AccessGP

Hot weather can feel enjoyable at first, especially after a long winter. But when temperatures rise, the body has to work harder to keep cool.

For most people, a warm day means drinking more, staying in the shade and taking things a little easier. But for some, heat can quickly become uncomfortable or even dangerous. Headaches, dizziness, tiredness, nausea, muscle cramps and feeling faint can all be signs that the body is struggling to cope.

Heat exhaustion is usually preventable and often improves if you cool down quickly. But if it is not recognised and treated, it can progress to heatstroke, which is a medical emergency.

This guide explains how to manage safely in hot weather, who is more at risk, how to recognise heat exhaustion, and when to seek urgent help.

Why hot weather can affect your health

Your body works hard to keep its temperature stable. In hot weather, it loses heat through sweating and changes in blood flow. This is normal, but it can leave you feeling drained, especially if you are not replacing enough fluid.

Heat can also affect sleep, appetite, energy levels, concentration and exercise tolerance. It can worsen headaches, dizziness, palpitations, fatigue and general “off” feelings.

For some people, the issue is straightforward dehydration. For others, the heat is only part of the story. Symptoms may also relate to blood pressure, medication, anaemia, thyroid problems, infection, anxiety, alcohol, caffeine, or an existing medical condition.

That is why a GP review can be useful when symptoms are persistent, unusual for you, or difficult to explain.

Common symptoms people notice in hot weather

Heat-related symptoms can vary. Some people feel mildly sluggish. Others feel suddenly quite unwell.

You may notice:

tiredness or weakness
dizziness or feeling faint
headache
nausea or reduced appetite
muscle cramps
heavy sweating
feeling very thirsty
a fast heartbeat
poor sleep
reduced concentration
darker urine or passing urine less often

These can fit with dehydration or heat exhaustion, but they are not always caused by heat alone.

The NHS lists tiredness, dizziness, headache, nausea, sweating, cramps, fast breathing or heartbeat, high temperature, thirst and weakness as possible signs of heat exhaustion.

Heat exhaustion: what to do first

If you think you or someone else may have heat exhaustion, the first step is to cool down.

Move to a cooler place. Stop activity. Remove unnecessary layers. Drink cool fluids if you can. Use cool water on the skin, damp cloths, a fan, or cold packs wrapped in a cloth.

Most heat exhaustion should improve with prompt cooling and fluids. UKHSA guidance explains that heat exhaustion does not usually need emergency medical attention if someone cools down within 30 minutes, but it can progress to heatstroke if action is not taken.

Do not return to exercise, heavy work or direct sun straight away. Give your body time to recover.

When it is not safe to “wait and see”

Hot weather can make people dismiss symptoms that actually need urgent help.

You should seek urgent medical advice if symptoms are severe, worsening, or not improving after cooling and fluids.

Call 999 or go to A&E if there is:

confusion
collapse or fainting
seizure
loss of consciousness
severe breathlessness
chest pain
symptoms of a stroke
a very high temperature with worsening illness
symptoms that do not improve after 30 minutes of cooling

Heatstroke is different from heat exhaustion. It is a medical emergency.

When a GP appointment may help

A GP appointment is not for emergencies, but it can be helpful when symptoms are not severe enough for urgent care yet still feel concerning.

For example, you may want to speak to a GP if:

dizziness keeps recurring
headaches are new or more frequent
you feel unusually tired despite resting
you are worried about dehydration
you have palpitations or feel your heart racing
hot weather has worsened an existing condition
you are taking medication and are unsure if the heat affects it
you have urinary symptoms, reduced urination or dark urine
you are not sure whether symptoms are heat-related
you need advice before travelling, exercising or returning to work

This is where private GP care can be useful. You do not always need hospital care, but you may still want a doctor to review the pattern, check for red flags and decide whether anything else needs investigating.

Medication and hot weather

Some medicines can make hot weather harder to manage.

This does not mean you should stop regular medication without advice. But it may be worth discussing medication with a GP or pharmacist if you are feeling light-headed, dehydrated, unusually weak, or more unwell than expected in the heat.

Medicines that may need extra care in hot weather include some blood pressure tablets, diuretics, antidepressants, antipsychotics, diabetes medication, antihistamines, and medicines that affect kidney function or fluid balance.

A GP can review your medication in context: your symptoms, medical history, blood pressure, fluid intake, kidney risk, and whether blood tests or follow-up may be appropriate.

Hydration: simple but easy to get wrong

Drinking more in hot weather sounds obvious, but people often underestimate how much fluid they are losing through sweat.

Signs you may not be drinking enough include thirst, dry mouth, tiredness, headache, dizziness, dark urine, or passing urine less often.

The NHS advises drinking more when there is a higher risk of dehydration, such as during hot weather or exercise, and using urine colour as a rough guide, aiming for pale urine.

Water is usually enough for most people. If you have been sweating heavily, vomiting, having diarrhoea, or struggling to eat and drink normally, oral rehydration solutions can sometimes help replace salts as well as fluid.

Alcohol can worsen dehydration and affect judgement. Caffeine may also contribute to feeling jittery, anxious or more aware of palpitations in some people.

Existing conditions can feel worse in the heat

Heat can put extra strain on the body. This may matter more if you already have a long-term health condition.

People with heart disease, high blood pressure, kidney disease, diabetes, asthma, COPD, neurological conditions, mental health conditions or mobility problems may be more vulnerable during hot weather.

Older adults, young children, pregnant women and people who live alone or in very warm homes are also at higher risk.

UKHSA advises that some groups are more vulnerable during hot weather, including older adults, young children and people with underlying health conditions.

If you are in one of these groups and feel unusually unwell in the heat, it is reasonable to seek medical advice earlier.

Practical ways to stay well in the heat

The aim is not to stop life every time the temperature rises. It is to reduce avoidable strain on your body.

Try to keep out of direct sun during the hottest part of the day. In the UK, this is often between 11am and 3pm. If you go outside, use shade, sunscreen, a hat and loose clothing.

Keep your home cooler where possible by closing curtains or blinds on sun-facing windows and opening windows when the air outside is cooler. Cool showers, cool drinks, damp cloths and lighter meals can help.

The NHS advises staying out of the heat where possible, staying in the shade between 11am and 3pm, wearing sunscreen, a hat and light clothes, and avoiding activity that makes you hotter.

If you exercise, adjust your expectations. Move exercise to early morning or evening, reduce intensity, take breaks, and stop if you feel dizzy, faint, nauseous, unusually weak or confused.

Looking after someone else

Heat-related illness can develop quickly in people who are vulnerable, especially if they live alone or struggle to communicate symptoms.

Check in on older relatives, neighbours, people with dementia, people with severe mental health problems, and anyone with mobility or long-term health issues.

Ask simple questions:

Are they drinking?
Are they passing urine normally?
Is the room too hot?
Do they feel dizzy or confused?
Have they eaten?
Do they need help moving somewhere cooler?

If someone seems confused, very drowsy, faint, severely weak or is not improving after cooling, seek urgent help.

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How AccessGP can help

At AccessGP, we provide online private GP appointments for adults.

We can help if you feel unwell in the heat and are unsure what to do next. A GP can assess your symptoms, consider whether they fit with dehydration or heat exhaustion, review medication, discuss existing conditions, and advise whether blood tests, blood pressure checks, in-person assessment or urgent care may be needed.

We can also help with related concerns such as headaches, dizziness, fatigue, palpitations, urinary symptoms, travel worries, medication reviews and heat-related flare-ups of existing conditions.

AccessGP is not an emergency service. If symptoms suggest heatstroke, collapse, chest pain, severe breathlessness, confusion or serious illness, you should seek urgent help immediately.

The bottom line

Hot weather can make you feel tired, dizzy, headachy, nauseous, dehydrated or generally unwell. Often, the answer is to cool down, rest and drink regularly.

But if symptoms are persistent, unusual, recurrent or affecting an existing condition, it may be worth speaking to a GP.

A private GP appointment can help you work out whether this is likely to be heat-related, whether medication or an underlying condition may be contributing, and what the safest next step should be.hreat your body is carrying and build a more stable routine around recovery.