Protecting your clients from extreme heat

Updated on December 7, 2023 (Originally posted on May 15, 2023) The Tablet
It's hot in B.C.

By Amy Lubik, PhD 
Climate Change and Planetary Health Lead, Fraser Health

Many people who are more vulnerable to extreme heat may not know that they are at risk, so may not take precautions. Older people are often at risk because their body’s ability to sense and regulate heat diminishes. People with cardiovascular disease, obesity, renal disease, respiratory illness, or mental health disorders such as addictions and schizophrenia, are particularly vulnerable (more information is available through the BCCDC). Those most disproportionately impacted during the 2021 heat dome had pre-existing medical conditions and were living in the community (i.e. not in supported living or other care facilities). Many were socially isolated and not well connected to the medical system.

Pharmacists can identify at-risk patients by medical history and current prescriptions. As trusted medical professionals, pharmacists are well-placed to provide brief counselling if they identify people whose conditions or medications may put them at risk, especially for people who may be socially isolated.

Drugs and heat

Medications that can put people at risk

Medications that impair the body’s ability to cool itself include: 

  • Beta blockers
  • Antihistamines 
  • Medications with anticholinergic effects (e.g. oxybutynin or benztropine)
  • Some antidepressants (e.g. amitriptyline or nortriptyline)

Medications that cause low blood pressure that can be worsened by hot temperatures include:

  • Medications for heart disease (e.g. nitroglycerin and calcium channel blockers)
  • Medications for high blood pressure (e.g. ACE inhibitors)

Medication that can increase body temperature include:

  • Antipsychotic medications (e.g. risperidone, olanzapine, or quetiapine)
  • Stimulation medications for attention disorders, such as amphetamines (e.g. Dexedrine® or Adderall®)

Medications that can cause dehydration or are affected by dehydration include:

  • Diuretics 
  • Laxatives
  • Some diabetes medications (e.g. canagliflozin or empagliflozin)
  • Some antidepressants (e.g. fluoxetine or venlafaxine)
  • Lithium
  • Some antiepileptics (e.g. phenytoin)
  • Warfarin
  • Digoxin

The relationship between taking medication and negative health impacts during hot weather is not straightforward. Heat illness may occur in anyone, not only those taking these medications. Heat illness can be fatal and urgent medical attention may be needed. For more information about extreme heat illness or other extreme weather hazards, please visit your regional health authority website or

Preparing for extreme heat

At the beginning of the heat season, prepare your staff to recognize patients who may be at risk and instruct them to provide brief counseling, such as:

  • Asking if the patient is aware of how their condition may make them more at risk to heat;
  • Asking them if they have air conditioning, or if not, if they have ways to monitor the temperature in their home;
  • Advising them to have a plan to keep their home cool or a plan to go somewhere, such as staying with friends or family or going to a municipal cooling shelter (or even a mall or air conditioned business);
  • Advising them to drink more water even if they are not thirsty, provided that they do not have conditions with fluid restrictions;
  • Instructing patients not to stop taking their medications unless instructed by healthcare providers;
  • Most significantly, advising patients or their caregivers to have a neighbour or loved one check in on them if there is a heat event, such as heat alert or heat emergency.

Pharmacists may also choose to post heat and smoke health posters on office walls or screens. Patient education materials on heat preparedness may be found on your local health authority website. Heat Posters, Summer Heat Safety for Seniors and People living with Medical Conditions, and Be Prepared for Summer Heat Wallet Cards are available for ordering (in multiple languages) through Fraser Health Authority Patient Education if you are located in that Health Region (please contact

Ministry of Health heat preparedness materials can be found on Information on Heat-related Illness and how to Beat the Heat are available in multiple languages as well as information on Medications and Heat. 



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