Heatwave Advice


The main risks posed by a heatwave are:

  • dehydration (not having enough water)
  • overheating
  • heat exhaustion
  • heatstroke

 Who is most at risk?

A heatwave can affect anyone, but those with long term (chronic) conditions are amongst the most vulnerable people in extreme heat, plus:

  • older people, especially those over 75
  • babies and young children
  • people with mobility problems
  • people with serious mental health problems
  • people on certain medications, including those that affect sweating and temperature control
  • people who are physically active, for example labourers or those doing sports

Diabetes insipidus patients

People lose more water though sweating than they think; this can be a problem for patients with diabetes insipidus (DI). You should ALWAYS obey your thirst and drink if you are thirsty.

A few patients on DDAVP don't sense thirst very well/ have no thirst mechanism, and will need (or need parents to) rely on keeping an eye on their fluid balance (water intake / urine output). They need to be aware that they will be losing more fluid (salt and water) through their skin than usual, when it is very hot – again, these patients should be advised to avoid prolonged exposure to the midday sun, and avoid extreme exercise / intense physical labour when it is hot. Children in this situation are probably particularly vulnerable, and parents should consult their peadiatric endocrine team if they are concerned about their child (or peadiatric A&E if out-of-hours).

If any patients also happen to have diabetes mellitus, and on insulin treatment, their blood sugars may be affected - partly because the insulin will be absorbed more quickly from hot skin and they should probably check blood sugars more regularly than usual and avoid dehydration.

For patients taking hydrocortisone – follow ‘sick day rules’ as usual

If you feel unwell, with a fever or infection, double your usual dose for duration of fever and see your GP if still unwell after 48 hours.

If you vomit more than once, and cannot keep an extra 10mg -20mg of tablets down, an emergency injection of 100mg hydrocortisone is needed. Phone your GP (if unwell in practice hours) or go to A&E. This also applies to severe diarrhea or illness.

Please see our Hydrocortisone advice leaflet for patients for further information

Medication storage

Medicines that must be stored in a fridge may deteriorate in a heatwave if the fridge does not keep the medication cool enough. Most fridge-storage medicines need to be kept between 2 and 8 degrees Celsius, so the temperature control in a patient’s fridge may need to be adjusted during a heatwave to meet this requirement.

For medicines that are not normally stored in a fridge, manufacturers generally guarantee that they remain stable if stored below 25 degrees Celsius. In a heatwave, ambient temperatures may rise above this. To protect these medicines, store them somewhere cool and out of direct sunlight (but not in the fridge). Avoid places that get very hot – such as in cars, or on sunny windowsills etc. It is important to store them out of the sight and reach of children.

Tips for coping in hot weather

The following advice applies to everybody when it comes to keeping cool and comfortable and reducing health risks:

  • Shut windows and pull down the shades when it is hotter outside. If it’s safe, open windows for ventilation when it is cooler.
  • Avoid the heat: stay out of the sun and don’t go out between 11am and 3pm (the hottest part of the day) if you’re vulnerable to the effects of heat.
  • Keep rooms cool by using shades or reflective material outside the windows. If this isn't possible, use light-coloured curtains and keep them closed (metallic blinds and dark curtains can make the room hotter).
  • Have cool baths or showers, and splash yourself with cool water.
  • Drink cold drinks regularly, such as water and fruit juice.
  • Plan ahead to make sure you have enough supplies, such as food, water and any medications you need.
  • Identify the coolest room in the house so you know where to go to keep cool.
  • Wear loose, cool clothing and a hat if you go outdoors.

How do I know if I, or someone I care for, needs help?

If you or someone you care for, feels unwell, find somewhere cool (out of the sun) to rest. Give plenty of fluids to drink.

If symptoms such as breathlessness, chest pain, confusion, weakness, dizziness or cramps get worse or don’t go away, seek urgent medical help.