Heat Exhaustion Signs and Symptoms: What to Do in the First 10 Minutes

Heat exhaustion gives you a short window to act. Here are the signs to check, a ten-minute cooling sequence in order, and the specific signals that mean heat stroke and a 911 call. Written for Phoenix summers, and reviewed by Dr. Patricia Sullivan, MD, MPH.

If someone near you is showing heat exhaustion signs and symptoms, get them out of the heat and into air conditioning before anything else. The next ten minutes decide whether this stays a bad afternoon or becomes an emergency. Below: the steps in order, the signals that mean you stop and call 911, and where IV hydration in the Phoenix heat fits afterward.

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What do I do in the first 10 minutes of heat exhaustion?

Move the person into air conditioning. Lay them flat and raise their legs. Loosen or remove extra clothing. Put cool wet cloths on the neck, armpits and groin, and keep air moving over wet skin. If they are fully awake and alert, give small sips of cool water. Reassess at ten minutes.

In this guide

The signs you are actually looking for
The first 10 minutes, minute by minute
When to call 911 instead of anyone else
When an in-home IV is and is not the right next step
Common questions about heat exhaustion
Get an IV in the Phoenix Valley
Service area

The Signs You Are Actually Looking For

Heat exhaustion and heat stroke call for two different responses, and telling them apart takes about thirty seconds. Maricopa County confirmed 427 heat-related deaths in 2025, down from 608 the year before (Maricopa County Department of Public Health). Our nurses see these calls cluster on the hottest afternoons, often from people who got caught out by a mid-day errand. The same rules apply to staying hydrated on Phoenix trails.

Early Signs of Heat Exhaustion

Someone with heat exhaustion is usually still sweating heavily, and their skin feels cool and damp rather than hot.

Heavy sweating with pale, cool, moist skin
A fast, weak pulse
Headache, dizziness or feeling faint
Nausea, muscle cramps, weakness or heavy fatigue
Strong thirst and passing less urine than usual

Those signs come from Maricopa County Public Health and CDC and NIOSH. If that is what you are seeing, start cooling now.

Signs That Mean This Is No Longer Heat Exhaustion

Any one of the following means heat stroke, and heat stroke is a 911 call, not a home-care decision.

Confusion, agitation, slurred speech or any change in how the person is thinking
Fainting, or being difficult to wake
Hot, dry, red skin where the sweating has stopped
A body temperature above 103°F
A seizure
Repeated vomiting, or refusing water

The sweating stopping is the signal people miss most often. It looks like relief. It is the opposite.

The First 10 Minutes, Minute by Minute

Get them out of the heat

Indoors, into air conditioning. A shaded patio is not a cool space at 112°F, and Phoenix averages 21 days a year at 110°F or hotter (National Weather Service Phoenix). A car with the air conditioning running works. Stop here and call 911 if they are confused or cannot be woken.

0 to 2 minutes

Lay them flat and start cooling

Flat on their back, legs raised slightly. Loosen or remove extra clothing, shoes and socks. Put cool wet cloths on the neck, armpits and groin, then get air moving across the wet skin. Wet skin plus moving air cools faster than either one alone.

2 to 5 minutes

Fluids, then reassess

Only if they are fully awake and alert, give small sips of cool water or an electrolyte drink. Nothing with alcohol or caffeine, and nothing by mouth for someone confused or vomiting. At ten minutes, check again: steadier and clearer means keep cooling and resting, any reversal sign means call 911 now.

5 to 10 minutes

When to Call 911 Instead of Anyone Else

Any one of the reversal signs above means call 911 now. Also call if there is no clear improvement after about an hour of cooling and rest. The American Red Cross and Mayo Clinic both draw the line at agitation, confusion, vomiting or loss of consciousness.

Keep cooling while you wait for the ambulance. Maricopa County guidance is to keep cooling until the body temperature comes down to roughly 101 to 102°F.

Why Driving Them Yourself Is the Wrong Call

Cooling continues in an ambulance and stops in a back seat. If someone is confused enough that you are weighing whether to drive them, that is already the answer: call 911.

When an In-Home IV Is and Is Not the Right Next Step

An in-home IV is not emergency care and is not a substitute for it. If any of the signs above are present, call 911. Nothing on this page changes that.

Where a mobile IV does fit is afterward: someone alert and oriented, through the acute episode, still depleted the next morning, whose stomach is not letting them catch up on fluids by mouth. It puts fluid and electrolytes into the bloodstream directly and bypasses digestion entirely. Individual results vary, and many clients report feeling better within 30 to 60 minutes.

Two treatments are relevant. A 1000ml IV fluids treatment is $150 and runs about 35 minutes, which is straight rehydration with nothing added. A Hydration IV is $175 for about 45 minutes and adds vitamin C, a B-complex blend and B12. Add-ons are $25 each, and service between 8:00 PM and 7:00 AM carries a $99 after-hours fee.

Every IV is started in your home by a licensed nurse or REMT, under the medical direction of Dr. Christopher Seitz, MD, a board-certified emergency physician.

Most people improve within 30 to 60 minutes of active cooling and fluids. Fatigue can linger for a day or two. No improvement after about an hour is the line at which this becomes an emergency-care question rather than a home-care one.

Heavy sweating with cool, moist skin points to heat exhaustion. Confusion, hot dry skin where sweating has stopped, and a body temperature above 103°F point to heat stroke, which is a 911 call.

Either works. Cool water or an electrolyte drink without caffeine or alcohol, in small sips, and only if the person is fully awake and alert. Never give fluids by mouth to someone confused or vomiting. More on how electrolytes actually work.

When someone is alert and past the acute episode but still cannot keep up with fluids by mouth. A 1000ml IV fluids treatment is $150 for about 35 minutes, started by a licensed nurse at your home. An IV is supportive care and is not a substitute for emergency care.

Sources and References

Maricopa County Department of Public Health. "Public Health Shares 2026 Heat Plan as Heat-Related Deaths Decline for Second Year" (March 2026), the source of the 2025 and 2024 heat-related death counts. maricopa.gov
Maricopa County Department of Public Health. "Signs of Heat-Related Illness," the source of the symptom lists, the 103°F heat stroke threshold, and the 101 to 102°F cooling target. maricopa.gov
CDC and NIOSH. "Heat-Related Illnesses," symptoms and first aid for heat exhaustion and heat stroke. cdc.gov
American Red Cross. "Heat Exhaustion: Symptoms, Causes, and Treatment," the source of the guidance to call 911 if the person refuses water, vomits, or loses consciousness. redcross.org
Mayo Clinic. "Heat exhaustion: First aid," the source of the guidance to seek emergency help if the person becomes agitated or confused. mayoclinic.org
National Weather Service Phoenix. Extreme temperature records and climate normals, the source of the average number of days a year at 110°F or hotter. weather.gov/psr
Phoenix Mobile IV Therapy public booking menu, the source of every price and session length on this page. janeapp.com

Get an IV in the Phoenix Valley

Once the acute episode has passed and you are still not catching up on fluids, call (480) 908-9266 or schedule online. A nurse can typically come to you the same day across the Phoenix metro, 24 hours a day. If symptoms are severe or worsening, or you suspect heat stroke, call 911 first.

Still depleted after the heat has passed?

Call for the fastest response, or schedule online. Same-day across the Phoenix metro, 24 hours a day.

Call (480) 908-9266

Or book online

Service Area

Phoenix Mobile IV Therapy comes to you across the Phoenix metro and the wider Valley. See the full Arizona service area for every city we cover.

Medically reviewed by Dr. Patricia Sullivan, MD, MPH

This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. IV therapy is administered by licensed nurses and REMTs under the medical direction of Dr. Christopher Seitz, MD, and is intended for supportive hydration, not as a treatment or cure for any condition. These statements have not been evaluated by the FDA. This service is not intended to diagnose, treat, cure, or prevent any disease. Individual results vary. Mobile IV therapy is supportive care, not emergency care. If you are pregnant, have severe or worsening symptoms, or suspect heat stroke, seek emergency care or call 911.