A heat wave is a prolonged period of extreme heat that stresses the body’s cooling system. It causes heat exhaustion (heavy sweating, dizziness, cramps) and heat stroke (no sweating, body temp above 40°C, confusion). Heat stroke is a medical emergency. Prevent both by staying hydrated, avoiding outdoor exposure between 12 PM and 4 PM, and wearing loose cotton clothing.
India is in the grip of an unusually intense heat wave this April. Cities across Maharashtra, Delhi, Hyderabad, Odisha, West Bengal, Navi Mumbai, and Goa are seeing temperatures cross 40°C, with Akola recording above 44°C. The IMD has issued red and moderate heatwave warnings across multiple states, and heat-related illness cases are already rising.
Below is a practical breakdown of causes, symptoms, treatment, and precautions.
What is a heat wave?
A heat wave is a period of abnormally high temperatures lasting at least two consecutive days, significantly above the normal range for that region. In India, the IMD defines a heat wave as temperatures reaching 40°C or more in plains and 30°C or more in hilly areas.
What causes heat waves in India?
Heat waves form when several weather conditions stack on top of each other at once:
- No western disturbances bringing rain or cloud cover
- Intense solar radiation heating large land areas fast
- Dry, hot winds blowing in from inland regions
- A “heat dome” effect, where warm air gets trapped near the surface
- Delayed pre-monsoon rains that would normally cool temperatures down
- Urban heat island effect, which makes cities like Delhi and Mumbai significantly hotter than surrounding areas
- Climate change, making extreme weather events more frequent and severe across India
This is why April is delivering temperatures that usually belong in May or June.
What is heat exhaustion?
Heat exhaustion is a heat-related illness where the body struggles to cool itself after prolonged exposure to high temperatures. It’s serious but manageable if caught early. Left untreated, it can progress to heat stroke.
Symptoms of heat exhaustion:
- Heavy sweating
- Weakness and fatigue
- Dizziness or lightheadedness
- Nausea or vomiting
- Muscle cramps (heat cramps), especially in the legs
- Cool, pale, clammy skin
- Rapid but weak pulse
- Headache
- Fainting (heat syncope)
- Dark urine and constant thirst, both early signs of dehydration
The first signs of heat exhaustion are usually dizziness and excessive sweating together. Don’t ignore either.
What is heat stroke (sunstroke)?
Heat stroke, also called sunstroke, is a medical emergency where the body’s temperature regulation fails and core temperature rises above 40°C. The body stops sweating and can’t cool down on its own. Without immediate treatment, heat stroke can cause organ failure.
Symptoms of heat stroke:
- Body temperature above 40°C
- Hot, red, dry skin with no sweating
- Rapid, forceful pulse
- Confusion, slurred speech, or loss of consciousness
- Seizures
- Severe headache and nausea
- Overheating with no ability to cool down
The one sign that separates heat stroke from heat exhaustion: sweating has stopped entirely.
Heat stroke vs heat exhaustion: what’s the difference?
| Heat Exhaustion | Heat Stroke | |
| Sweating | Heavy sweating | No sweating |
| Skin | Cool, pale, clammy | Hot, red, dry |
| Body temp | Below 40°C | Above 40°C |
| Consciousness | Alert, may feel faint | Confused or unconscious |
| Pulse | Rapid, weak | Rapid, forceful |
| Treatment | Cool down at home | Emergency care immediately |
| Urgency | Serious | Life-threatening |
With heat exhaustion, the body is still working to cool itself. With heat stroke, that mechanism has failed. That difference determines whether you manage it at home or call emergency services.
What is hyperthermia?
Hyperthermia is an abnormally high body temperature caused by the body’s inability to regulate heat, usually from external heat exposure. It’s not the same as a fever. A fever is a deliberate immune response to infection. Hyperthermia is uncontrolled. Heat stroke is its most severe form.
Hyperthermia symptoms include hot dry skin, rapid pulse, confusion, and body temperature above 40°C.
also read – https://clinikk.com/blog-understanding-the-importance-of-preventive-healthcare-how-regular-check-ups-can-save-your-life/
What are the precautions during a heat wave?
Timing and environment:
- Stay indoors between 12 PM and 4 PM when heat peaks
- Use fans, coolers, or AC; if unavailable, find a community cooling space
- Keep curtains closed on sun-facing windows to reduce indoor temperature
- Cool, wet cloths on the neck and wrists bring body temperature down faster than most people expect
Hydration:
- Drink water consistently through the day, not just when thirsty
- Use ORS solutions, coconut water, or lemon water with a pinch of salt to replace electrolytes
- Sports drinks work in a pinch, but watch the sugar content
- Avoid alcohol and excess caffeine; both speed up dehydration
Clothing and outdoor exposure:
- Wear loose, light-colored cotton clothing and a wide-brimmed hat outdoors
- Apply sunscreen before stepping out
- Skip strenuous physical activity during peak afternoon hours
Monitor vulnerable people:
- Elderly family members, young children, pregnant women, and people with diabetes, hypertension, or heart disease face higher risk
- These groups lose heat tolerance faster and may not recognize symptoms in themselves
- Check on them regularly on extreme heat days
How do you treat heat exhaustion?
Heat exhaustion can be managed at home if caught early:
- Move the person to a cool, shaded space immediately
- Lay them down and elevate their legs slightly
- Give water or an electrolyte drink in small, steady sips
- Apply cool, wet cloths to the skin
- Use a fan to improve airflow
- Monitor closely; symptoms should improve within 30 to 60 minutes
Most people recover fully within a few hours. Some fatigue may linger for 24 to 48 hours. If symptoms worsen or don’t improve, get a medical evaluation.
How do you treat heat stroke?
Heat stroke requires emergency medical care. Call emergency services first. While waiting:
- Move the person out of the heat into shade or indoors
- Apply ice packs or cold water to the neck, armpits, and groin
- Fan the person continuously
- Don’t give liquids if the person is unconscious or confused
- Stay with them until help arrives
Don’t try to manage heat stroke at home. The faster the body temperature drops, the better the outcome.
When should you see a doctor for heat illness?
Seek medical help if:
- Symptoms don’t improve after an hour of cooling and hydration
- The person is confused, disoriented, or behaving unusually
- Body temperature is above 39°C
- Fainting doesn’t resolve within a few minutes
- The person has diabetes, hypertension, or a heart condition
Clinikk offers telemedicine consultations. You can get assessed without going outside in the heat.
Frequently Asked Questions
What are the first signs of heat exhaustion?
Dizziness and excessive sweating together are usually the earliest warning. Nausea, muscle cramps, and a weak pulse tend to follow. Move to a cool area and start hydrating as soon as either appears.
What are the symptoms of heat stroke?
Heat stroke symptoms include body temperature above 40°C, hot dry skin with no sweating, a rapid forceful pulse, confusion or loss of consciousness, and seizures. It requires immediate hospital care.
What are the symptoms of sunstroke?
Sunstroke symptoms are identical to heat stroke: high body temperature, no sweating, red dry skin, confusion, rapid pulse, and sometimes seizures. The two terms refer to the same condition.
What is hyperthermia and how is it different from fever?
Hyperthermia is an uncontrolled rise in body temperature caused by heat exposure. A fever is the immune system deliberately raising temperature to fight infection. They look similar but have different causes and need different responses.
How long does heat exhaustion last?
With prompt cooling and hydration, most cases resolve within a few hours. Some tiredness may persist for 24 to 48 hours. If symptoms aren’t improving by then, get a medical evaluation.
What is heat syncope?
Heat syncope is fainting from heat exposure, caused by reduced blood flow to the brain. It’s an early warning sign of heat illness. Lay the person down, elevate their legs, move them somewhere cool, and give water.
What are heat cramps?
Heat cramps are painful muscle spasms, most often in the legs or abdomen, caused by fluid and electrolyte loss during heat exposure. They’re a symptom of heat exhaustion. Rest, hydrate, and replace electrolytes with ORS or coconut water.
What is heat stress?
Heat stress is the physical strain the body experiences when it can’t maintain a safe internal temperature in hot conditions. Prolonged heat stress leads to heat exhaustion and, without treatment, heat stroke.
What are the side effects of dehydration?
Dark urine, headache, nausea, fatigue, dizziness, confusion, and a rapid heartbeat are all common. In severe cases, dehydration can also cause fever and organ strain.
What is the treatment for sunstroke? Sunstroke needs emergency care. While waiting for help, move the person out of the heat and apply ice or cold water to the neck, armpits, and groin. Fan them actively. Don’t give fluids if they’re unconscious.
