Preventing heat stroke comes down to managing three things: your hydration, your exposure, and your body’s ability to cool itself. Heat stroke occurs when your core temperature reaches 104°F (40°C) or higher, and it’s a medical emergency that can cause confusion, seizures, organ damage, and death. The good news is that it’s almost entirely preventable with the right habits.
Know the Warning Signs Before They Escalate
Heat stroke doesn’t usually strike out of nowhere. It typically follows a progression from heat exhaustion, giving you a window to intervene. Heat exhaustion shows up as heavy sweating, nausea, dizziness, a rapid pulse, and cool or clammy skin. At this stage, your body is still trying to cool itself and mostly succeeding.
Heat stroke is different. The hallmark is a change in mental state: confusion, agitation, slurred speech, irritability, or in severe cases, seizures and coma. Sweating may stop entirely. If you or someone near you starts acting disoriented in the heat, that’s a red flag that the body’s cooling system has failed. Recognizing heat exhaustion early and acting on it is one of the most effective ways to prevent heat stroke from ever happening.
How Much Water You Actually Need
Thirst is a lagging indicator. By the time you feel thirsty, you’re already mildly dehydrated, and dehydration directly impairs your body’s ability to sweat and regulate temperature. OSHA recommends drinking at least one cup (8 ounces) of water every 20 minutes while working or exercising in the heat, not just when you’re thirsty. That works out to about 24 ounces per hour as a baseline.
If you’re doing intense physical work or exercise, you may need more, and you’ll also want to replace electrolytes lost through sweat. Sports drinks, electrolyte tablets, or even lightly salted water can help. Avoid alcohol and heavily caffeinated drinks on extremely hot days, as both can accelerate fluid loss. Start hydrating before you go outside. Playing catch-up in the heat is harder than staying ahead of it.
Plan Around the Heat, Not Through It
The simplest prevention strategy is reducing your exposure during peak heat. The hottest part of the day in most regions falls between 10 a.m. and 4 p.m. If you have flexibility in your schedule, shift outdoor exercise, yard work, or errands to early morning or evening hours.
When you can’t avoid midday heat, build in rest breaks. Spend 10 to 15 minutes in shade or air conditioning for every 45 to 60 minutes of heat exposure. This gives your core temperature a chance to drop before it climbs into dangerous territory. If you work outdoors, OSHA has proposed a federal heat standard that would require employers to provide a heat safety plan including access to shade and water. Even without a formal rule in place, those principles apply to anyone spending extended time in the heat.
What to Wear in Extreme Heat
Your clothing choices have a measurable impact on how efficiently your body sheds heat. The goal is to maximize airflow against your skin and allow sweat to evaporate, which is your body’s primary cooling mechanism. Tight, heavy, or dark-colored clothing works against both of those goals.
Lightweight, loose-fitting, light-colored clothing is the standard advice, but the fabric matters too. Linen, with its open weave and natural fibers, is one of the most breathable options. Chambray (a lightweight plain-weave cotton) and seersucker (which has a raised texture that creates air pockets) also promote strong airflow. For athletic or work settings, moisture-wicking synthetic blends pull sweat away from your skin to the fabric’s outer surface, where it evaporates faster. Fabrics like Tencel and bamboo offer both breathability and strong moisture-wicking properties. A wide-brimmed hat protects your head and face, where blood vessels sit close to the surface and absorb heat quickly.
Give Your Body Time to Adjust
Acclimatization is one of the most underappreciated tools for heat stroke prevention. Your body adapts to heat over roughly 7 to 14 days of gradual exposure, becoming more efficient at sweating, maintaining blood volume, and regulating core temperature. People who jump straight into intense heat exposure without this adjustment period, whether they’re starting a new outdoor job, traveling to a hotter climate, or resuming exercise after time off, are at significantly higher risk.
If you’re heading into a period of heat exposure, ramp up gradually. Start with shorter, less intense sessions and increase duration and effort over one to two weeks. This applies to athletes, outdoor workers, and anyone moving to a hotter region. The first few days of a heat wave are particularly dangerous because most people haven’t had time to acclimatize.
Medications That Impair Your Cooling System
A wide range of common medications interfere with your body’s ability to regulate temperature, and many people taking them have no idea they’re at increased risk. According to the CDC, the major categories include diuretics (water pills), beta blockers, and other blood pressure medications. These can reduce blood flow to the skin or deplete fluids your body needs for sweating.
Psychiatric medications also carry significant risk. Antipsychotics, SSRIs, SNRIs, tricyclic antidepressants, lithium, and ADHD stimulants can all impair thermoregulation through different mechanisms. Some reduce sweating, others increase heat production, and certain combinations amplify the danger. Taking a blood pressure medication like an ACE inhibitor alongside a diuretic, for example, can significantly increase the risk of heat-related harm beyond what either drug would cause alone.
Antihistamines with anticholinergic effects (like diphenhydramine, the active ingredient in Benadryl), anti-seizure medications, thyroid replacement hormones, and even over-the-counter pain relievers like NSAIDs and acetaminophen are on the list. If you take any of these, you don’t need to stop your medication, but you do need to take extra precautions in the heat: more water, more shade, more rest breaks, and a lower threshold for heading indoors.
Cooling Strategies That Work Best
If you or someone else is overheating, the speed of cooling matters enormously. Cold water immersion, essentially getting into a tub of cold water, is the gold standard. Studies of heat stroke patients at road races found cooling rates averaging about 0.4°F per minute with cold water immersion, which is fast enough to prevent organ damage in most cases. Other methods like dousing with cold water and using fans, or applying ice towels, do work but cool the body at a slower rate.
For everyday prevention rather than emergency treatment, practical cooling tactics include draping a cold, wet towel around your neck, using a spray bottle with a fan, taking cool showers, and spending time in air-conditioned spaces. If your home doesn’t have air conditioning, public libraries, malls, and community cooling centers can serve as heat refuges during the worst hours of the day.
Pre-cooling before exercise or outdoor work can also help. Drinking an ice slurry or cold water before heading out lowers your starting core temperature, giving you more thermal headroom before you reach dangerous levels. While the performance benefits for athletes are debated, the basic physics hold: starting cooler means it takes longer to overheat.
Who Faces the Highest Risk
Certain groups are more vulnerable to heat stroke and need more aggressive prevention. Adults over 65 have a diminished ability to sense and respond to temperature changes, and they often take multiple medications that compound the risk. Young children, especially infants, have immature thermoregulation systems and can’t tell you when they’re overheating.
People with chronic conditions like heart disease, diabetes, and obesity are also at elevated risk because their cardiovascular systems are already working harder to maintain normal function. Athletes and outdoor workers face high risk simply because of prolonged exertion in heat. And people who are socially isolated, living alone without air conditioning or regular check-ins, account for a disproportionate share of heat-related deaths during heat waves. If you know someone in these categories, checking on them during extreme heat is a simple act that can prevent a tragedy.