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This guide to heat exhaustion and heat stroke was medically reviewed by Dr. Kiyan Rad, DO — Medical Director, Sanova Urgent Care, Tucson, AZ
It starts as a headache on the back nine, or a wave of nausea unloading the car at 2pm. You feel wrung out, a little dizzy, maybe cramping. In Tucson, that is not "a bit of sun." It is the body telling you it is losing the fight with the heat — and the next stage, heat stroke, kills.
This guide to heat exhaustion vs. heat stroke gives you the line between the two, what to do in the first 30 minutes, and when to walk in for IV fluids rather than keep sipping water.
Open Monday–Saturday, 7:00 AM – 7:00 PM · Closed Sunday
15883 N Oracle Rd, Suite 101, Tucson, AZ 85739
Medically reviewed by Dr. Kiyan Rad, DO, board-certified internal medicine physician and Medical Director, Sanova Urgent Care
The National Weather Service's Tucson climate normals put the average daily high at 101.2°F in June and 100.2°F in July — and those are averages, not the bad days. The record is 117°F.
What makes the desert different from humid heat is that sweat evaporates almost instantly. You don't feel drenched, so you don't register how much fluid you are losing. By the time thirst catches up, you may already be two or three pounds of water down. That is the mechanism behind most of the heat exhaustion we see: not one dramatic exposure, but a hot afternoon of doing normal things without drinking enough.
It adds up locally. Pima County's own heat health indicator reports heat-related emergency room visits at 35.7 per 100,000 residents and notes heat-related hospitalizations and deaths have risen over the last decade.
The distinction is drawn from CDC/NIOSH and National Weather Service guidance. Heat exhaustion is a warning. Heat stroke is a 911 call.
| Heat exhaustion | Heat stroke | |
|---|---|---|
| Mental state | Alert, but weak, dizzy, headachy | Confused, slurred, agitated, passing out, or seizing |
| Skin | Heavy sweating; cool, pale, clammy | Hot and red — may be dry or still sweating |
| Pulse | Fast, weak | Fast, strong |
| Other signs | Nausea, vomiting, muscle cramps, thirst, less urine | Very high body temperature, throbbing headache |
| What to do | Cool down, sip water, get evaluated | Call 911. Cool aggressively. Do NOT give fluids. |
| Where | Urgent care | Emergency room, by ambulance |
The single most useful question: is the person thinking clearly? Confusion means heat stroke until proven otherwise.
These are the National Weather Service's first-aid steps, in order.
Get out of the heat. Air conditioning beats shade. A car with the AC on full counts.
Loosen or remove clothing and lie down with legs slightly raised.
Cool the skin. Cool wet cloths on the neck, armpits and groin; a cool (not ice-cold) shower if they can stand safely.
Sip water or an electrolyte drink — sips, not chugging, which brings on vomiting. Skip alcohol and energy drinks.
Watch the clock and the head. If symptoms aren't clearly improving within an hour, if vomiting stops fluids going down, or if the person becomes confused at any point — that is the moment to act.
Improving after an hour of this is the expected course. Not improving is the reason to be seen.
Oral rehydration works when the gut cooperates. It doesn't when someone is vomiting, too nauseated to drink, light-headed every time they stand, or simply so far behind that sipping won't catch up before the next day's heat. That is what IV fluids are for.
At Sanova we can give IV hydration on site the same visit, add anti-nausea medication so you can keep fluids down afterwards, and run blood work here to check electrolytes and kidney function — the two things heat and dehydration hit first. Most patients leave in a couple of hours feeling human again. There's more on how a walk-in IV visit works in our IV therapy guide.
Symptoms last more than an hour despite cooling and fluids · you can't keep liquids down · you feel faint standing up · you're barely urinating, or it's dark · you have heart or kidney disease, or take diuretics or blood-pressure medication · it's a child or an older adult.
CDC/NIOSH is blunt: heat stroke is fatal if treatment is delayed. Call 911 for any of these, then start cooling while you wait:
While waiting: move them to shade or AC, strip outer clothing, soak them with cool water and fan them, and put ice or cold packs on the neck, armpits and groin. Do not give fluids to someone who is confused or drowsy — they can choke. An ambulance can cool and treat on the way; a car cannot.
Everyone can overheat. For these groups, the gap in heat exhaustion vs. heat stroke closes faster, and with less warning.
The body's heat response weakens with age, thirst is blunted, and common medications get in the way. CDC advises asking your provider how your medications affect you on hot days — we can do that at the visit.
Working through the afternoon peak with the wrong fluids. Heat cramps in the calves and abdomen are the early warning. If your employer needs a work-injury visit, we do occupational medicine here.
Children heat up faster than adults and don't always say so. Watch for a kid who goes quiet, flushed and clumsy at practice.
The classic Tucson case: a 9am start that becomes a 1pm finish. Carry more water than seems reasonable and turn around at half of it.
These blunt sweating, thirst, or the heart's response to heat. Bring your medication list.
Higher fluid needs and less tolerance for overheating. Err on the side of being seen.
We're at 15883 N Oracle Rd, Suite 101 — the walk-in clinic on the Oracle Road corridor with IV fluids and labs in the building, serving Oro Valley, Rancho Vistoso, Catalina, SaddleBrooke, Sun City Oro Valley and Marana.
$140 self-pay visit; IV hydration from $90. Medicare, AHCCCS, Tricare and major plans accepted. Costs and insurance.
Dr. Kiyan Rad, Beth Brown FNP, and Kim Wall FNP. Meet the team.
| Day | Hours |
|---|---|
| Monday–Saturday | 7:00 AM – 7:00 PM |
| Sunday | Closed |
With cooling and fluids, most people feel noticeably better within an hour and normal within a day, though fatigue can linger. Symptoms that don't improve within an hour, or get worse, need evaluation.
Yes. Untreated heat exhaustion can progress to heat stroke, which is life-threatening. The warning sign of that transition is a change in mental state - confusion, slurred speech, agitation or passing out. Call 911 at that point.
If you can keep fluids down and improve within an hour, oral rehydration is usually enough. If you're vomiting, faint on standing, barely urinating, or not improving, IV fluids replace what you've lost far faster and we can give them on site.
Heat exhaustion: heavy sweating, weakness, dizziness, nausea, cramps - but thinking clearly. Heat stroke: hot skin, very high body temperature and confusion, collapse or seizure. Heat exhaustion is urgent care; heat stroke is 911.
Yes. Sanova Urgent Care at 15883 N Oracle Rd, Suite 101 is minutes from SaddleBrooke, Sun City Oro Valley and Catalina, with IV fluids and lab testing on site. No appointment needed, Monday to Saturday 7am to 7pm.
No. The National Weather Service and CDC both advise not giving fluids to someone with heat stroke - a confused or drowsy person can choke. Call 911 and cool them with water on the skin, fanning, and ice packs to the neck, armpits and groin.
Yes. Diuretics, some blood-pressure drugs, beta blockers and antihistamines can reduce sweating, blunt thirst or limit the heart's response to heat. Bring your medication list so we can review it with you.
Heat exhaustion vs. heat stroke can come down to minutes. If an hour of cooling and sipping hasn't fixed it, walk in. IV fluids, anti-nausea medication and blood work on site.
Sanova Urgent Care · 15883 N Oracle Rd, Suite 101, Tucson, AZ 85739 · Get directions
This article is for general information and does not replace an evaluation by a licensed provider. In an emergency, call 911.
Dr. Kiyan Rad, DO, is a board-certified internal medicine and obesity medicine physician and Medical Director of Sanova Urgent Care in Catalina, AZ, serving Oro Valley, SaddleBrooke and north Tucson. He is an Assistant Clinical Professor of Medicine at the University of Arizona College of Medicine – Tucson, President of the Medical Executive Committee at Encompass Health Rehabilitation Hospital of Northwest Tucson, and former Chief of Medicine at Carondelet St. Joseph’s Hospital. He earned his DO from Michigan State University College of Osteopathic Medicine. On this blog, he shares practical guidance on urgent care, chronic disease, metabolic health and recovery after a hospital stay.
