Extreme heat is not just a passing annoyance: it can trigger heat stroke, a rapidly progressing medical emergency and can be fatal if not treated immediately. High temperatures, high humidity, and lack of hydration are the perfect breeding ground for the body to lose its ability to cool itself.
In this guide you will find a clear explanation of the symptoms, causes, risk groups, what to do (and what not to do) in the event of heat stroke, and how to prevent it with proper hydration and smart habits. Key recommendations on medication and drug storage during the warmer months are also included, as well as references to public heat wave warning plans.
What is heat stroke?
Heat stroke is the most severe form of heat injury: body temperature rises to ≥40°C and the body stops regulating itself. It can occur after prolonged exposure to hot and humid environments, or due to intense physical exertion in the heat, with particular risk if there is no adaptation or sufficient hydration.
This is a real medical emergency, with potential for brain damage, multi-organ complications, and even death if treatment is delayed. Although it is more common in summer, it can occur at any time of year if heat, humidity, and dehydration occur.
Symptoms and warning signs
Detecting the signs early makes all the difference: The sooner the person cools down and receives assistance, the better the prognosis.
- Very high temperature (≥40 °C; persistent fever difficult to control).
- neurological alterations: confusion, irritability, disorientation, drowsiness, difficulty speaking, delirium, seizures, or coma.
- Hot, reddened skin and with little or no sweating (sometimes abundant sweating if it was due to intense exercise).
- Headache intense or throbbing.
- Nausea and vomiting, general malaise.
- Fast breathing and superficial.
- Accelerated pulse (marked tachycardia).
- Fainting or loss of consciousness.
In the early stages, muscle cramps and a feeling of suffocation may appear., especially if there was physical activity in conditions of high heat and dehydration.
When to seek urgent help and first aid
If you suspect heat stroke, call 112 (or your local emergency number) without delay. Every minute counts to prevent damage to the brain, heart, kidneys and muscles.
While help arrives, act: Move the person to a cool or shady place, remove excess clothing and encourage cooling.
- Active coolingCool showers, cold washcloths, and a mist fan. Apply cold compresses to your neck, armpits, and groin.
- Bath or immersion: Some health sources recommend cold water immersion as an effective method in controlled environments; Others warn to avoid sharp contrasts Outside of professional facilities due to a potential risk to circulation. If trained personnel are unavailable, prioritize gradual cooling.
- Oral hydration: Only if the person is conscious and can swallow small amounts of water or electrolyte drinks, without alcohol or caffeine.
- If there is no breathing or pulse, start CPR if you know how.
What not to do: Do not administer antipyretics (paracetamol, ibuprofen) to “lower the fever” of heat stroke and do not rub with alcohol due to the risk of cutaneous and systemic toxicity.
Causes and triggers
There are two main routes: classic heat stroke (hot and humid environment, prolonged exposure) and exertional heat stroke (intense physical activity in the heat).
- Hot environment: indoors or outdoors with high temperatures and humidity maintained, especially in older people or those with chronic illnesses.
- Strenuous effort: training, physical work or sports in the heat without acclimatization.
Factors that precipitate or aggravate: thick or very tight clothing that prevents evaporation of sweat, alcohol consumption (reduces thermoregulation), and dehydration due to insufficient fluid intake compared to losses through sweating.
Factors riesgo
Although anyone can suffer from it, some profiles are more vulnerable: Extreme caution should be taken during heat waves and during acclimatization.
- Age: young children (immature CNS) and people over 65 years of age (lower adaptability and lower thirst sensation).
- Activity in heat: military, athletes (football, marathon), outdoor workers.
- Sudden exposure to heat: first waves of summer or trips to warm climates; the body takes several weeks to fully adapt.
- Lack of air conditioning: Fans provide relief, but air conditioning is more effective at lowering temperature and humidity.
- Medication: Vasoconstrictors, beta-blockers, diuretics, antidepressants/antipsychotics and stimulants (including cocaine) increase the risk.
- Chronic diseases and conditions: heart disease, lung disease, obesity, physical inactivity, and history of heat-related events.
Possible complications
The longer the body temperature remains elevated, the greater the damage: Rapid cooling saves organs and lives.
- Damage to vital organs: cerebral edema or involvement of other organs with permanent sequelae.
- Risk of death if intervention is not carried out promptly and appropriately.
Prevention and key habits
Heat stroke prevention is entirely possible if you plan hot days well and adjust your activity and hydration.
- Hydrate before you get thirstyWater is the base; if you sweat a lot, add electrolyte solutions.
- Avoid central hours (12:00–17:00): Look for shade or cool interior.
- Light and loose clothing cotton, linen, silk, or hemp; light colors and breathable fabrics.
- Photoprotection: wide-brimmed hat, glasses, and broad-spectrum sunscreen (SPF ≥15), reapplying every 2 hours (or sooner if you swim or sweat).
- Progressive acclimatization: Gradually increase the duration and intensity of your warm-up effort over several days/weeks.
- Avoid alcohol and limit caffeine, which promote dehydration.
- Don't leave anyone in a parked car, not even in the shade or with open windows.
- Plan breaks and rests If you can't postpone work or training, find cool places to recover.
If you take drugs that increase the risk, redouble precautions and consult your healthcare professional about specific measures during heat waves.
Hydration, medication and kidney health
Some medications alter hydration, blood pressure, or thermoregulation., which makes you more susceptible to heat.
- Diuretics: increase the loss of fluids and electrolytes.
- Antihypertensives and beta-blockers: They can lower blood pressure too much in the heat; avoid sudden changes in posture and monitor blood pressure.
- Antidepressants, anxiolytics and antipsychotics: interfere with thermal regulation and sweating.
- Anti-inflammatories: in dehydration, can damage the kidneyDon't self-medicate and drink enough water.
- Antihistamines and other psychiatric medications: can aggravate heat intolerance.
Practical keys to hydration: Don't wait until you're thirsty, spread your intake throughout the day, and if you experience vomiting or diarrhea, use oral rehydration fluids (not just water).
Correct storage of medicines and heat
Heat and humidity degrade drugs and excipients, reducing effectiveness and safety; caring for them is part of your health.
- places to avoid: parked cars (can exceed 60°C), bathrooms (humidity in showers), kitchens (heat sources) and windows/balconies (direct sunlight).
- Ideal place: a cool, dry cupboard, away from heat and light; guideline temperature 15–25 °C (always refer to the package leaflet) and keep in its original packaging.
Drugs that require refrigeration (2–8 °C): insulin (vials in use can be kept <30°C for 4–6 weeks), some liquid antibiotics and biologics (e.g., certain arthritis or cancer treatments). At home, best stored on the middle shelves of the refrigerator. never at the door due to thermal instability.
Extra tips: : for traveling, use a portable refrigerator with accumulators (not direct ice) and do not freeze medications (crystallization damages proteins such as insulin).
Drugs that increase risk and heat-sensitive medications
In addition to those that affect thermoregulation, there are sensitive presentations that lose properties >25–30 °C.
- nitroglycerin (angina), thyroid hormones, some antiretrovirals.
- Suppositories and ovules: they melt and alter the dose.
If you take antibiotics or other photosensitizing drugsProtect your skin with strict sun protection and limit sun exposure; store the containers in a cool place and seek medical attention if vomiting or diarrhea occurs.
How to detect spoiled medicines and transportation in summer
Check for signs of deterioration before consuming any drug that has been exposed to heat.
- Tablets/capsules: cracks, stickiness, changes in color or odor.
- Syrups/suspensions: phase separation, lumps or crystallization.
- Creams/ovules: too liquid or oily consistency.
- Injectables: turbidity or particles.
What to do: Do not use them; consult your pharmacist and check the package leaflet (some presentations include visual indicators, e.g., color in insulin).
Safe transportation: If you need to move sensitive medication, use a cooler with a thermometer (keep 2–8 °C in refrigerated containers), avoid the trunk and use an air-conditioned vehicle. For insulin, do not prolong exposure to >30°C for more than 1–2 hours.
Heat stroke vs. heat exhaustion
Distinguishing both situations guides the appropriate response: Heat exhaustion is milder and treatable with rest and hydration, while heat stroke requires urgent attention.
| Symptom | heat exhaustion | Heatstroke |
|---|---|---|
| Body temperature | Up to 39 °C | ≥40°C |
| Welder | Abundant | Scarce or absent |
| State of mind | Fatigue, dizziness | Confusion, loss of consciousness |
| Skin | Cold and wet | Hot, dry, reddened |
| Treatment | Rest + hydration | Medical emergency |
In case of heat exhaustion: Move to a cool area, undress, take a warm shower/bath or wet the body, rest, and consult a doctor if there is no improvement. For children, increase breastfeeding if they are breastfeeding and offer frequent, small sips of fluids.
Children and the elderly: specific care
KidsTheir thermoregulatory system is immature and they dehydrate quickly; they must be closely monitored in hot environments.
- Warning signs: irritability, crying without tears, very hot skin, drowsiness or weakness.
- Prevention: more frequent breastfeeding, safe water and natural juices (avoid caffeinated and sugary drinks), light clothing and frequent baths.
- What not to do: Do not expose them to direct sunlight between 10:00 and 16:00, never before 1 year; do not leave them in closed cars.
- Performance If you suspect heat stroke: emergency or call 112, cool quickly with fresh water, remove clothing and offer water only if conscious.
Greater: They may perceive heat less well and sweat less; their thirst sensation is lessened, and they often take medications that increase their risk.
- Care: Keep the home cool and ventilated, increase hydration even if you are not thirsty, and monitor your temperature if you feel unwell.
- Avoid: alcohol and excessive caffeine; intense exertion during hot weather.
Heat wave alerts and public plans
Public surveillance systems issue alerts in advance to facilitate information and protection measures for the vulnerable population.
Example: Community of Madrid. It defines risk thresholds by isoclimatic zones: Sierra de Madrid ≈ 34,1 °C; Metropolitana and Henares ≈ 35,9 °C; Sur, Vegas and Oeste ≈ 35,3 °C, with a provincial maximum temperature threshold with a health impact of ≈ 35,6 °C.
- Level 0 (Normality): usual summer situation.
- Level 1 (Caution): risk for the most vulnerable population.
- Level 2 (High risk): risk for the entire population, especially vulnerable people.
Activations and deactivations are communicated to health centers, allowing for targeted interventions (elderly, infants <12 months, chronically ill, dependent persons, and those requiring specific medication). Technical documents help a safe use of medications in heat waves. Consult official materials such as the preventive advice guide: recommendations for the heat.
FAQ
Can heat stroke occur without direct sunlight? Yes: even in hot, poorly ventilated interiors, in closed vehicles, or when exercising in hot, humid environments.
Who does it affect the most? Young children, the elderly, patients with chronic illnesses, overweight people, and those taking certain medications; as well as outdoor workers and athletes.
It can be avoided? With constant hydration, appropriate clothing, rest during peak hours, ventilated or air-conditioned spaces, and gradual acclimatization.
What health bulletins exist? Many healthcare institutions offer free newsletters with previews and tips; personal data management is governed by their privacy policies, and you can unsubscribe at any time.
Protecting yourself from the heat requires foresight, strategic hydration, common sense when exposed to the elements, and a clear plan for responding to symptoms. Following these guidelines reduces serious complications and makes a difference for children, the elderly, and people with medical conditions or sensitive medications.