Heat-related illnesses: preparing for periods of high temperatures

With climate change making periods of high temperatures more likely, pharmacists need to engage in early preparation and provide effective support for heat-vulnerable individuals.
Hand opening hot blinds and peering through window.

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With increasing global temperatures and the associated increased likelihood of hot days, long-term planning and strategic management of heatwaves is critical to prevent excess mortality​[1–3]​. It is a national and global priority to minimise future global warming through reduced emissions, protect people’s health through public health campaigns and heat-warning systems, and adapt to climate change (e.g. through urban planning and housing design)​[1,3]​. Healthcare professionals have a vital role to play by suitably organising their services and in disseminating information to the general public, particularly to individuals vulnerable to heat. This article is the second in a two-part series and focuses on preparing for periods of high temperatures. Information on the physiological impact of heat and the symptoms associated with heat-related illnesses can be found in ‘Heat-related illnesses: physiology, symptoms and management’.

Staying well during a heatwave

Heat-related illness and mortality increases within one to two days of high temperatures​[3]​. Heat-related morbidity and mortality is largely preventable; therefore, preparation for heatwaves and prevention of heat-related illness is essential. This is particularly important for heat-vulnerable individuals (see Box).

Box: Individuals who are vulnerable in hot conditions

  • People with poor cognition, owing to a mental health condition or disability;
  • Children;
  • Older people;
  • People with pre-existing medical conditions (e.g. diabetes, renal disease, heart failure);
  • People who are overweight or obese;
  • People with unconventional lifestyles, such as those who are homeless, abuse alcohol or use illicit drugs;
  • People who work outdoors, such as gardeners and farmers.

Early detection of upcoming heatwaves and keeping informed of developments allows healthcare professionals to prepare for and reduce risk during heatwaves. The UK Health Security Agency operates a five-tier heat-health alert system between June and September each year to warn the public of upcoming high temperatures (see Table 1).

Early level 2–4 heatwave weather warnings are issued by the Met Office for UK regions and are regularly updated throughout heat periods​[2,3]​. Local health organisations and news platforms also provide information and updates at these times​[2,3]​. Healthcare professionals can provide support by cascading information to the public — particularly to high-risk individuals. Emergency government response guidance is available online to provide support and manage and reduce risk​[3]​.

Public health and patient education is vital. Healthcare professionals should particularly discuss heat-related risks with vulnerable individuals so that they are aware of how any of their conditions and medications might be affected by hot weather​[4]​. This advice can be given at routine reviews and ahead of or during hot weather, including specific guidance for medicines that reduce heat tolerance (see Table 1). People can also be signposted to specific patient resources and guidance for long-term health conditions. For example, online resources are available for those with diabetes, kidney, lung and heart conditions​[5–10]​. Patients should be advised to keep medicines in a cool, dark place or at recommended temperatures as per their individual specifications. A summary of general hot weather advice is detailed in Table 2. 

Impact of heat on the workplace

Employers have a legal duty to ensure workplaces are maintained at a reasonable temperature and the working environment is safe. There is no legal maximum temperature for workplaces, as this will vary according to the work environment; however, employers must be aware of the UK heat-health alert system and have in place an appropriate heatwave plan to keep staff safe and well in hot weather. More information is available on the Health and Safety Executive website​[11]​.

Medicines storage and temperature monitoring during heatwaves

Periods of extreme heat also affect the delivery of services but there are practical things that pharmacy professionals can do to prepare for heatwaves.

Correct storage of medication is important to ensure longevity and prevent early degradation. Most medication should ideally be stored at ambient temperatures (below 25oC), which is usually specified on the packaging. Cold-chain products require a stricter temperature control of 2–8oC (e.g. insulins and certain aseptically prepared products within the hospital setting).

Clinical environments are at risk of temperature excursions during a heatwave. Act on any temperature excursions quickly, and raise any concerns with the governance team, ensuring adherence to local policies and guidelines where appropriate.

During a heatwave, take care when delivering medications to patients or receiving deliveries from manufacturers, paying close attention to cold-chain products (these must be stored quickly in the fridge to prevent exposure to heat). In the event of a heatwave, it is good practice to monitor stock levels, keeping numbers low and ensuring effective stock rotation​[12]​. It is also a good idea to check that the temperature monitoring systems in place are working. Advise patients who use cold-chain medicines to invest in a fridge thermometer and ensure they check their appliances regularly in a heatwave. In cases of ambient temperature excursions, or where fridges may have malfunctioned, the summary of product characteristics for individual products should be consulted for advice. The Specialist Pharmacy Service website also has information on reducing expiry dates for medicines that have been exposed to environmental temperature breaches​[12]​. To manage a temperature excursion of a work appliance, see Table 3 and refer to local standard operating procedures where appropriate.


  • Further increases in hot days and heatwaves are expected owing to climate change;
  • Extreme heat can have direct and indirect negative consequences on health, particularly in heat-vulnerable individuals; 
  • Public health and individual patient education is needed to reduce heat-related risk; 
  • Temperature excursions must be processed according to local policy, and medicines requiring cold storage must be handled with extra care during a heatwave.
  1. 1
    Heat and health. World Health Organization. 2018.https://www.who.int/news-room/fact-sheets/detail/climate-change-heat-and-health (accessed May 2023).
  2. 2
  3. 3
    Hot weather and health: guidance and advice. UK Health Security Agency. 2023.https://www.gov.uk/government/collections/hot-weather-and-health-guidance-and-advice (accessed May 2023).
  4. 4
    Alied M, Huy NT. A reminder to keep an eye on older people during heatwaves. The Lancet Healthy Longevity. 2022;3:e647–8. doi:10.1016/s2666-7568(22)00198-2
  5. 5
    Advice for kidney patients during a heatwave. Kidney Care UK. 2022.https://www.kidneycareuk.org/news-and-campaigns/news/advice-risk-kidney-patients-during-heatwave/ (accessed May 2023).
  6. 6
    Diabetes and hot weather. Diabetes UK. 2023.https://www.diabetes.org.uk/guide-to-diabetes/managing-your-diabetes/hot-weather (accessed May 2023).
  7. 7
    Hot weather and diabetes — staying safe in the heat. Diabetes.co.uk. 2023.https://www.diabetes.co.uk/diabetes-and-hot-weather.html (accessed May 2023).
  8. 8
    Looking after your lungs in hot weather. Asthma and Lung UK. 2021.https://www.diabetes.co.uk/diabetes-and-hot-weather.html (accessed May 2023).
  9. 9
    Hot weather and your heart. British Heart Foundation. 2021.https://www.bhf.org.uk/informationsupport/support/practical-support/weather-and-your-heart (accessed May 2023).
  10. 10
    It’s summertime, beware of heat illness. National Kidney Foundation. 2023.https://www.kidney.org/news/monthly/Its_Summertime_Beware_of_Heat_Illness (accessed May 2023).
  11. 11
    Temperature in the workplace. Health and Safety Executive. 2023.https://www.hse.gov.uk/temperature/index.htm (accessed May 2023).
  12. 12
    Understanding why temperature management is important for medicines storage. Specialist Pharmacy Service. 2023.https://www.sps.nhs.uk/articles/understanding-why-temperature-management-is-important-for-medicines-storage/ (accessed May 2023).
Last updated
The Pharmaceutical Journal, PJ, May 2023, Vol 310, No 7973;310(7973)::DOI:10.1211/PJ.2023.1.185985

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