Last updated: 02.03.23

Treating Heat Exhaustion or Heat Stroke - Signs & Symptoms

Please note that this information does not qualify you as an official first aider, and Virtual College advise calling 999 in the first instance at the scene of an emergency.

This material and any associated assessments do not constitute a qualification or accreditation as an official first aider. All content provided is for general information only.

Heat exhaustion and heat stroke are both conditions caused by a person becoming too hot and suffering from the symptoms that are related to this. Both conditions are serious, but prolonged heat stroke can be life-threatening, so it is important to know how to prevent and treat it. 

Whether you’re a trained first aider or not, you may find yourself having to deal with someone that has heat exhaustion or heat stroke, especially when the weather is warm. In this article, we’re going to explain the signs of heat exhaustion, how to help heat stroke and heat exhaustion, and how to prevent them in the first place.

What are Heat Exhaustion and Heat Stroke?

Heat stroke and heat exhaustion are both conditions that arise from becoming too hot and can be serious in nature. There are a variety of things that can cause them, but the most common is simply not taking the correct precautions during hot weather or a heatwave.

Heat exhaustion is generally the first stage of the two, and occurs when a person becomes hot to the point that they begin to lose excess water and/or salt from their body through sweating, causing a variety of symptoms. It’s usually caused by being in a hot environment for an extended amount of time, especially if you’re not used to high temperatures.

Heat stroke is a more dangerous condition, which often develops after heat exhaustion, and is where the body is no longer able to regulate its temperature properly and cannot cool down. It can also be caused by having a very high fever or taking recreational drugs like ecstasy.

Sunstroke is a term commonly used to describe this condition, which simply refers to heat stroke caused by excessive exposure to the sun.

Heat exhaustion can develop into heat stroke if it’s not recognised in time and treated, and heat stroke can lead to serious medical complications including unconsciousness and death. Therefore, understanding the signs of heat exhaustion and proper treatment for heat stroke is incredibly important, especially in the summer months.

What are the Symptoms of Heat Stroke?

Heat exhaustion and heat stroke can cause a variety of different symptoms. Not all of these will occur in all people, and not all of them are easy to identify. 

However, the most commonly encountered signs of heat exhaustion are the following:

  • Hot and flushed skin
  • Tiredness, weakness or feeling faint and dizzy
  • Heavy sweating
  • Irritability
  • Signs of dehydration such as thirst or decreased urination
  • A loss of appetite
  • Feeling sick or vomiting
  • A heat rash
  • Muscle cramps 
  • Headaches
  • Low blood pressure or a faster pulse

Heat stroke has many of the same symptoms as heat exhaustion, as it tends to follow if heat exhaustion isn’t treated. The key thing to notice is that a person with heat stroke cannot regulate their body temperature and cool down, so may still be experiencing the above symptoms after 30 minutes.

As well as these symptoms, a person with heat stroke may also experience:

  • Confusion and disorientation
  • A body temperature above 40°C
  • Lack of responsiveness
  • Loss of consciousness
  • Seizures

How to Treat Heat Stroke and Heat Exhaustion

If you suspect that someone is suffering from heat exhaustion or heat stroke, then there are a variety of steps you can take to alleviate their symptoms. 

Treatment for heat exhaustion includes the following:

  • Move the person to a cooler location, particularly one inside if they have been outdoors, and have them lie down.
  • Have them drink plenty of fluids, preferably water, but sports drinks and juices are good alternatives.
  • Cool them down through whatever means available. This can include using a wet cloth on the back of the neck, removing some of their clothes, and fanning them.
  • After their symptoms have improved, continue to monitor the person for the next few hours and keep them cool and hydrated

The above steps should help most people to recover from heat exhaustion, but if the symptoms do not alleviate within around 30 mins, then you should seek emergency help by calling 999. If any of the symptoms are particularly severe, such as seizures or unconsciousness, then you should call the emergency services immediately.

Whilst you are waiting for the emergency services to arrive, the best treatment for heatstroke is to wrap the person in a cool, wet sheet and pour cold water over the sheet until their temperature starts to fall. You should continue this until their temperature is at least 37.5°C and then replace the wet sheet with a dry one.

If you don’t have access to a sheet, you can continually sponge the person with cold water to keep them cool.

The above steps should be continued until medical help arrives. You should continue to monitor the person’s temperature and level of responsiveness during this time and stay with them whilst you wait for the emergency services.

If the person with heat stroke falls unconscious, they should be placed into the recovery position. If they stop breathing, you should prepare to give them CPR until an ambulance arrives.

How to Avoid Heat Stroke and Heat Exhaustion

While both heat exhaustion and heat stroke are serious, they are entirely avoidable if you take precautions in hot weather or in hot environments.

Staying hydrated is also very important, and as a result, you should drink plenty of fluids, while avoiding excessive consumption of alcohol and caffeine. Cool drinks will also help you to keep your temperature down.

Keep an eye on the weather in order to be prepared. If you know it’s hot outside, then try to stay out of the sun during the midday peak, stay in the shade where possible, wear appropriate clothing, and don’t over-exert yourself physically. If you feel yourself starting to get dehydrated or overheated, move inside, rehydrate and try to stay out of the sun until it cools down.

If you’re with other people, particularly those susceptible to heat-related conditions, then look out for them too. Try to keep babies, children and elderly people indoors and cool with air conditioning, drinks and minimal activity.

In general, take all the precautions you can to keep your temperature down, and help others do the same.

Who is Most at Risk?

As with a great many conditions, certain people are more likely to be at risk of either heat exhaustion or heat stroke. These are people either who are physically more susceptible to the symptoms, or who are more likely to be in a situation that causes a heat-related condition.

Babies, young children and the elderly are particularly at risk from these conditions, so the focus of prevention must be on them. In addition, people with generally poor health, or who are already suffering from long-term issues are less likely to be able to control their body temperature well. Their condition may also exacerbate the symptoms of heat exhaustion or heat stroke.

Healthy adults are still at risk from both of these conditions if they undertake a lot of physical activity in hot environments. Members of the military, manual workers and people exercising are such examples. 

Heat exhaustion and heat stroke are also more likely to happen to people visiting or living in very hot countries, especially if they’re not used to persistent high temperatures. The majority of people may be at risk of heat stroke or heat exhaustion at some point in their lives, so it’s important for everyone to be aware of the risks.


What are the signs of heat stroke in a child?

The signs of heat stroke and heat exhaustion in children are pretty similar to the symptoms in adults, including excessive sweating, dizziness and tiredness, a headache, muscle cramps, reduction in urination and feeling sick or vomiting. Babies and younger children may not be able to describe the symptoms they’re experiencing, which makes it important to know and be able to spot heatstroke symptoms so you can treat them quickly. 

What's the difference between heat stroke and heat exhaustion?

Heat exhaustion often comes before heat stroke, and occurs when a person becomes so hot that they lose a lot of water and salt through excessive sweating, causing a range of symptoms. Heat stroke happens when someone’s body can no longer regulate their temperature and they can’t cool down, which can lead to serious complications and even death if it’s not treated quickly.

How long do symptoms of heat exhaustion last?

For the majority of people, the symptoms of heat exhaustion will start to improve within 30 minutes. Whilst you may still feel unwell for the rest of the day, drinking lots of fluids and staying cool will help manage these symptoms and get you back to normal.

If the symptoms of heat exhaustion last for longer than 30 minutes then heat exhaustion may have developed into heat stroke. If you cannot improve these symptoms then urgent medical treatment is needed and you should call 999.


Whilst the complications of heat exhaustion can be severe, it is a condition that is very easy to prevent with the appropriate measures. Since the UK isn’t a particularly hot country, many people are unaware of early heatstroke symptoms and how to treat them, which can lead to more serious medical emergencies when someone does become unwell because of the temperature. But as long as you recognise the signs and know how to avoid heat exhaustion, you can keep yourself and the people around you safe. 

If you’re looking for first aid training that can help you to identify and manage conditions like treating heat exhaustion, our ‘First Aid at Work’ course focuses on the Primary Survey and can help people learn how to respond in a first aid situation like heat exhaustion and heat stroke.