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When temperatures rise, staying hydrated becomes an important part of protecting your health. Your body relies on water to regulate temperature, support circulation, aid digestion, and keep organs and muscles functioning properly.
Hot weather, physical activity, illness, and spending long periods outdoors can all increase fluid loss. Without enough replacement fluids, dehydration can develop and make it more difficult for your body to manage the heat.
The good news is that dehydration and many heat-related illnesses are preventable. By recognizing the early signs and building simple hydration habits into your routine, you can stay safer, healthier, and more comfortable throughout the summer.
Dehydration occurs when your body loses more fluid than it takes in. This can happen when you do not drink enough, but it can also result from sweating, fever, vomiting, diarrhea, or certain medications.
During hot weather, your body produces sweat to help release heat and maintain a safe internal temperature. As you sweat, you lose both water and electrolytes. If these fluids are not replaced, dehydration can gradually develop.
Anyone can become dehydrated, but the risk may be higher for:
Older adults may be particularly vulnerable because chronic health conditions, medications, social isolation, and changes in the body’s response to heat can increase their risk during extreme temperatures.
Dehydration does not always begin with severe symptoms. In many cases, the first signs can be easy to overlook or mistaken for ordinary fatigue.
Common signs may include:
Health Canada identifies extreme thirst, dry mouth, unusually dark urine, decreased urination, headache, nausea, dizziness, and a rapid heartbeat as possible signs of heat exhaustion and dehydration during hot weather.
Urine colour can offer a useful general clue about hydration. Pale yellow urine commonly suggests that you are drinking enough, while darker urine may indicate that you need more fluids. However, medications, supplements, and certain health conditions can also affect urine colour.
Thirst is an important signal, but it may not always tell you early enough that your body needs fluids. Health Canada advises drinking water before you feel thirsty during extreme heat because thirst is not always a reliable indicator of dehydration.
This can be especially important for older adults, whose sensation of thirst may become less noticeable with age.
Rather than waiting until you feel very thirsty, try drinking fluids regularly throughout the day. You may need additional fluids when you are:
Individual fluid needs vary depending on age, body size, activity level, health conditions, medication use, and temperature. People who have been advised to limit fluids because of kidney, heart, or another medical condition should follow the guidance of their healthcare provider rather than increasing their intake independently.
Hydration does not have to involve complicated schedules or special products. A few consistent habits can make drinking enough fluids easier.
Have a glass of water after waking up or with breakfast. Beginning the day hydrated can make it easier to maintain your fluid intake later.
Carry a reusable water bottle when you leave home and keep water visible at your desk, in the kitchen, or beside your usual chair. Seeing it can serve as a reminder to drink.
Drink before, during, and after exercise, yard work, walking, or other outdoor activities. Take breaks in shaded or air-conditioned areas, particularly during the hottest part of the day.
People who are physically active can develop heat-related illness even when they are generally healthy, especially when activity involves prolonged heat exposure or overexertion.
Water is often the simplest choice for everyday hydration. To add variety, try including lemon, lime, cucumber, berries, mint, or other fruit and herbs.
Milk, unsweetened fortified plant-based beverages, and some caffeine-free drinks can also contribute to overall fluid intake.
Fluids do not come only from beverages. Fruits and vegetables such as watermelon, oranges, berries, cucumber, tomatoes, lettuce, and celery contain water and can support hydration as part of a balanced diet.
Health Canada recommends drinking plenty of water and eating more fruits and vegetables during extreme heat.
If you frequently forget to drink, use phone reminders, calendar notifications, or regular daily activities as prompts. For example, take a few sips every time you eat, take medication, finish a meeting, or return from a break.
Alcohol can affect judgment and make it more difficult to notice early signs of dehydration or heat illness. When drinking alcohol, alternate with water and avoid prolonged heat exposure.
For most people completing routine daily activities, water and balanced meals are usually enough to support hydration.
Electrolyte replacement may be helpful after prolonged or intense exercise, heavy sweating, or fluid loss caused by vomiting or diarrhea. Oral rehydration solutions are specifically formulated to replace water and electrolytes and may be recommended in certain situations.
Sports drinks can contain significant amounts of added sugar and sodium, so they are not always necessary for casual activity. Anyone with diabetes, high blood pressure, kidney disease, or another condition affected by sugar, sodium, or fluid intake should speak with a healthcare professional before regularly using electrolyte products.
Dehydration and heat-related illness can occur together, but they are not identical.
Dehydration refers to insufficient fluid in the body. Heat exhaustion occurs when the body has difficulty managing heat and may include:
When these symptoms appear, move to a cool or shaded location, loosen unnecessary clothing, rest, and drink water if the person is awake and able to swallow. Health Canada recommends moving to a cool place and drinking liquids immediately when symptoms of heat exhaustion develop.
Severe dehydration and heat stroke require urgent medical attention.
Call 9-1-1 if someone:
Heat stroke is a medical emergency. While waiting for help, move the person to a cool place and begin cooling them with wet cloths, cool water, or other available methods. Do not force fluids if the person is confused, unconscious, vomiting, or unable to swallow safely.
Hydration and heat safety are also community responsibilities. During heat warnings, check on family members, friends, neighbours, and colleagues who may be at greater risk.
Someone may need additional support if they:
Encourage regular fluid intake, help them access a cooler environment, and pay attention to changes in behaviour, alertness, or physical condition.
Staying hydrated is not about drinking a large amount all at once. It is about replacing fluids consistently and adjusting your routine when temperatures, activity levels, or health needs change.
Keep water nearby, drink before you feel very thirsty, include water-rich foods, and reduce strenuous activity during the hottest hours of the day. Most importantly, pay attention to how you and those around you are feeling.
Recognizing dehydration early can help prevent symptoms from progressing and make it easier to enjoy the summer safely.
If you are experiencing persistent symptoms, have questions about medication and hydration, or are concerned about how a health condition may affect your response to heat, speak with a healthcare professional.
MembersHealth members can connect with the Care Team for medical guidance, support navigating symptoms, and help determining appropriate next steps. If symptoms are severe or suggest heat stroke, call 9-1-1 immediately.