Summer Heat, Drugs and Alcohol

Ah summertime! Sunshine, blue skies, what more could you ask for? A breeze maybe?

It is a very enjoyable time for many people, but there are some things to keep in mind to avoid heat problems and serious illness, especially if the thermometer has been high for several days in a row.

In the summer, the combination of high heat, high humidity and smog can be very dangerous [See Humidity Index at the bottom of the page]. Some people need to be extra careful during this time to make sure they don't run into heat related problems. This may include you. For example, you need to be extra careful if you:

-       Drink heavily

-      Take medications for mental health problems

-      Are older [especially if you are 75 or older with health problems]

-    Are overweight,

-    Are  "bedridden" or have difficulty getting around, or

-      Have heart or lung problems.


Why the Concern?

In the summertime, extreme and prolonged exposure to heat can disturb the way your body uses water and minerals, as well as the way your body regulates heat. 

This loss of fluids can pose a serious health threat both to older adults living in the city and to older adults in rural areas (particularly those working outside such as farmers, gardeners, boaters).  This can lead to heat exhaustion and heat stroke.

Older adults living in the upper storeys of high apartments can be particularly affected, as can people who don't have access to air conditioning, or who don't have trees around their home to provide shade and reduce the heat.

Medical conditions  such as diabetes and heart-related diseases as well as some drugs increase the risk for developing heat stroke. But most of the time the problems can be avoided by taking proper precautions and pacing yourself.



There are many types of medication that may increase a person's risk of heat-related illness. Many of these are commonly prescribed to older adults for health problems. These include anti-parkinson drugs, antidepressants, antihistamines, anti-diarrhea pills, some diuretics, and psychiatric drugs. Click here to find out more about heat and these medications.

If you are taking any medication regularly, ask your doctor or pharmacist if you need to be extra careful during hot weather.

Alcohol, Colas and Coffee

Alcohol, cola and coffee all can leave you dehydrated quickly. If at all possible, try to reduce the amount of these favourite beverages, especially during hot weather. Plain or flavoured water is a good substitute. 

Most teas have caffeine too (often as much as coffee), and surprisingly, your glass of iced tea may have more caffeine than hot tea. Click here for some caffeine amounts.

Alcohol inhibits a hormone called anti-diuretic hormone (ADH) in your body that controls urination. With ADH inhibited,  you'll increase the urge to "relieve yourself". Going more often, in turn leaches out crucial electrolytes like calcium, magnesium, zinc and phosphorus. The more alcohol that you drink, the more likely you are of becoming dehydrated.

Also, alcohol affects people's judgment. The more alcohol you drink, the harder it becomes for you to tell if the heat is getting to you and to tell if you may have a heat related illness. Also, those around you may not recognize the difference between a person who has had "a few too many" and who looks tired and dizzy,  and a person with  heat exhaustion.

People who have had long time drinking problems are more likely to be in poor health, or have medical problems or be on medications. All of these means they are at greater risk of developing heat stress.



An Ounce of Prevention


Toronto Public Health offers these suggestions for other things you can do to keep from becoming ill during hot periods:

-      Drink lots of water and juice, even if you don’t feel thirsty. Try to stay out of the sun, especially in the middle of the day. If you have to be outside, stay in the shade as much as possible.

-      If you can get a hat, wear it.

-      Wear loose fitting, light clothing.

-      Try to take it easy, and rest as much as possible.

-      If you have to walk a long way, try to do it in the early morning or evening.

-      Try to spend time in cool places with air conditioning like drop-ins and community centres.

-      Take a cool shower from time to time. Some drop-ins and recreation centres have public showers.

-      Try to spend some time near the lake or waterfront where it is cooler.

-      If you sleep outside during the day, try to sleep in the shade. Remember the sun moves, so try to sleep in a spot that will be shady for a few hours.


Some cautions and more suggestions from other health authorities:

-      Warning: If your doctor generally limits the amount of fluid you drink or has you on water pills (diuretics), ask her or him how much you should drink while the weather is hot.

-    A sports beverage can replace the salt and minerals you lose in sweat, but if you are on a low-salt diet, talk with your doctor before drinking a sports beverage.    

-      Stay indoors and, if at all possible, stay in an air-conditioned place. If your home does not have air conditioning, go to the shopping mall or public library–even a few hours spent in air conditioning can help your body stay cooler when you go back into the heat.

What else works? Find good ways of keeping the heat out of your house or apartment.  Some people find that closing the blinds of their home in the daytime to keep out the sun helps, and then opening up the blinds at night to let out the heat that builds up during he day.


Can electric fans prevent heat-related illness? 
Electric fans can help you feel more comfortable if the temperature is in the 70s or 80s (Fahrenheit) [ that is 21.1 to 26.6 degrees Celsius]. But when the temperature is in the high 90s (e.g. over 36 degrees Celsius), fans will not prevent heat-related illness.

Take a cool shower or bath or go to an air-conditioned place for the afternoon. It is a much better way to cool off. Air conditioning is the strongest protective factor against heat-related illness. Exposure to air conditioning for even a few hours a day will reduce the risk for heat-related illness. Consider visiting a shopping mall or public.



 Reduce the Harm


Cutting out or cutting down on alcohol in the summertime are probably the safest bet. Here are some other alternatives that may reduce the risk of heat related illness when drinking in the heat.


Really enjoy your summertime beers?

-      If you decide to have beer or other alcoholic beverages, drink lots of water before, during and after.

-      Try a lower alcohol or a non-alcohol version of beer. The quality of the non-alcohol beers has really improved over the past 5 years. Some of the brewing companies [especially the imported European] have developed very good tasting non-alcohol (<.05 % alcohol) beers which you can often pick up at your grocery store. Find a variety that you like.

-    Or consider the English approach: beer mixed with ginger beer. This also works with the non-alcoholic beers.


Like your wine?

-      If you decide to have  wine, why not try adding soda water, a little sugar, sliced fruit and ice cubes to it in a tall glass.  This is refreshing, increases the amount of fluids you are getting, takes longer to drink, and will have less alcohol in it.

-      Or alternate your alcoholic drink with a drink without alcohol in it. Try to limit or avoid the colas though, because the caffeine in them will also tend to dehydrate you.

-    There are non-sodium soda waters available in some grocery stores.


Are coolers better?

Well, coolers contain alcohol, so the general caution about the "more you drink, the greater the chance of dehydration and confusion" will still be the same.

Be careful with your home made versions of coolers. A "slip of the hand", and they can easily end up with more alcohol in them.  Coolers have double the calories of beer (280 calories vs. 150), and some may have a lot of sugar which affects your body's ability to regulate heat.

No alcohol cocktails ("mocktails") can be a good non-alcoholic alternative for you and your guests who choose not to drink.



Like your colas or iced coffee?

If your favourite summer beverage is a soda pop that has caffeine in it [only colas in Canada have caffeine], or an iced coffee or iced tea, be sure to also drink plenty of water. Like alcohol, caffeine is a diuretic which can lead to dehydration and loss of electrolytes.



Consumer Medicine Information, LOMOTIL. Online at: (e)/lomotil/lomotilcln.pdf

Evans, B. (May 1, 2003) A silent killer strikes the fireground. Online at:

Hett, H. A. & Brechtelsbauer, D.A. (June 1998). "Heat-related illness". Vol. 103 (6), Postgraduate Medicine. Online at:

Kilbourne, E. M., Choi, K., Jones, T.S. & Thacker, T.B. (1982). Risk factors for heatstroke: A case-control study. Journal of the American Medical Association (JAMA), 247 (24): 3332-36. Online at :

Warning: Heat Exhaustion & Allergy Sufferers. Online at:

Toronto Public Health. Medications and Heat-Related Illness. Online at :

Toronto Pubic Health. Summer Safety: Heat, Drugs and Alcohol. Online at:

Yale New Haven Health. Medications that increase the risk for a heat-related illness. Online at:

York, K. (August, 2000) "Consumers: Take care in the heat." Interface. Online at:

Zoghby, J.C. (Jul. 22, 1995). Medications can magnify heat dangers: Special warnings given for older people. Mobile Register, Section: 1B, 6B Online at :



Temperature in Celsius

Relative Humidity

25% 30% 40% 50% 60% 70% 80% 90% 100%
38 42 43 47 54 57 * * * *
37 40 42 45 49 54 55 58 * *
36 39 40 43 47 51 56 57 58 *
35 37 38 42 45 48 51 54 57 *
34 36 37 41 43 47 49 52 55 58
33 34 36 38 42 44 47 50 52 55
32 33 34 37 39 42 45 47 50 52
31 31 33 35 38 40 43 45 48 50
30 31 31 34 36 38 41 43 46 48
29 29 30 32 34 37 38 41 44 46
28 28 29 31 33 35 37 39 41 45
27 27 28 29 31 33 35 37 39 41
26 26 27 28 29 31 33 35 37 39
25 25 26 27 28 30 32 33 35 37
24 24 25 26 27 28 30 32 33 35
23 23 23 24 25 27 28 30 32 33
* = Beyond the Earth atmosphere's ability to hold water vapor.


Humidex - General Heat Stress Index
Danger Category Humidex

Heat Syndrome

Extreme Danger > 55 Heatstroke imminent with continued exposure.
Danger 40 - 54 Great discomfort. Avoid exertion. Seek a cool shady location. Heat cramps or heat exhaustion likely. Heat stroke possible with continued exposure and / or physical activity.
Extreme Caution 30 - 39 Some discomfort. Heatstroke, heat exhaustion and heat cramps possible with prolonged exposure and / or physical activity.
Caution < 29 Little discomfort. Fatigue possible with prolonged exposure and / or physical activity.


NOTE: Degree of heat stress may vary with age, health and body characteristics





Page last updated: July 28, 2003

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