You are on the kitchen floor by the back door because it was the coolest thing within reach. Your head hurts, you feel sick, and the part that does not fit is how little you sweated for a walk that hard. You take a water pill, you have not eaten or drunk much all week, and the working theory on the way home was that you are simply unfit. Two agencies publish sign lists that separate the heat illness you cool down from the one that is a call for help, and one item on the emergency side is the thing you noticed. Read both lists and you can tell which side of them this evening belongs on.
Which list barely sweating is on
Barely sweating belongs to the heat stroke list rather than the heat exhaustion one, and heat stroke is a medical emergency. NIA describes it as a medical emergency in which the body's temperature rises above 104°F, with signs of fainting; confusion or acting strangely; not sweating even when it's hot; dry, flushed skin; strong, rapid pulse; or a slow, weak pulse. CDC's version allows either hot dry skin or profuse sweating, so sweat alone settles nothing. NIA's heat exhaustion entry goes the other way on that one point — you may sweat a lot — with the rest reading thirsty, dizzy, weak, uncoordinated and nauseated, skin that may feel cold and clammy, and a body temperature that may stay normal.
One sign is not a verdict, and this sign least of all. CDC's occupational page gives heat stroke symptoms as confusion, altered mental status or slurred speech; loss of consciousness; hot, dry skin or profuse sweating; seizures; and very high body temperature. Hot dry skin or profuse sweating: heavy sweating does not rule heat stroke out there, and light sweating does not rule it in. What separates the lists is the head rather than the skin — confusion, altered speech, fainting and loss of consciousness sit on one side and not the other.
The two lists, and what each one says to do
The instruction column is where these lists really part, and it is the column worth reading first.
| Heat exhaustion | Heat stroke | |
|---|---|---|
| Signs, as NIA gives them | You might feel thirsty, dizzy, weak, uncoordinated and nauseated; you may sweat a lot; body temperature may stay normal; skin may feel cold and clammy; some people have a rapid pulse | Fainting; confusion or acting strangely; not sweating even when it is hot; dry, flushed skin; strong, rapid pulse; or a slow, weak pulse |
| What NIA says to do | Rest in a cool place and get plenty of fluids. If you do not feel better soon, get medical care | Seek medical help right away and immediately move to a cooler place, such as under shade or indoors; lower body temperature with cool clothes, a cool bath or shower, and fans |
| What CDC's page for workers says to do | Take the person to a clinic or emergency room for medical evaluation and treatment; call 911 if medical care is unavailable; have someone stay with them; move them out of the heat and give liquids; remove unnecessary clothing; cool with cold compresses or washing head, face and neck with cold water; encourage frequent sips of cool water | Call 911 for emergency medical care; stay with the person until help arrives; move to shade and remove outer clothing; cool rapidly with a cold water or ice bath if possible, wet the skin, cold wet cloths, circulate air |
The rows come from NIA's hot weather page and CDC's page on heat-related illnesses, the second written for workplaces, which is why its instructions address somebody standing next to you. NIA supplies the sentence joining the columns: heat exhaustion can progress to heat stroke, which is why its own instruction does not stop at rest and fluids.
A shorter NIA sentence reaches your evening directly. Headache, confusion, dizziness, or nausea could be a sign of a heat-related illness, it says, and go to the doctor or to an emergency room to find out if you need treatment. Two of those four are what you walked in with. MedlinePlus puts the general version under its heat stroke signs: if you see any of these signs, get medical help right away.
Why a water pill and a thin week are on the same list
A water pill and a week of eating and drinking less both appear on NIA's risk list, alongside seven other things, rather than standing as rival explanations for the afternoon. The list is written about older adults and says so — factors that put older adults at greater risk may include health problems such as cardiovascular, lung, or kidney disease; changes in skin caused by normal aging; any illness that causes weakness or results in a fever; taking drugs such as diuretics, sedatives, tranquilizers, and some heart and high blood pressure medicines that may make it harder for the body to cool itself; being on several prescription drugs at the same time; having obesity, overweight, or underweight; drinking alcoholic beverages; living in places without air conditioning or fans; and becoming dehydrated.
That population qualifier is NIA's and it stays. Where a page speaks to everyone it says less: MedlinePlus has older adults, young children, and those who are sick or overweight are most at risk, and adds that taking certain medicines or drinking alcohol can also raise your risk, without naming which medicines. CDC compresses it to many medicines can make you dehydrated or overheated on hot days, then adds: don't stop or change your medicines until you talk to your doctor.
Two of NIA's nine entries land on what you told yourself on the way home. A water pill is a diuretic, and becoming dehydrated is what a week of not eating or drinking much tends to produce. That is not a diagnosis and not a reason to change anything you take on your own, but it does make the weather at least as good a candidate as being unfit.
Questions for whoever prescribes the water pill
NIA has already written these as questions, which spares you composing one. The first: ask your doctor if any of your medications make you more likely to become overheated or sunburned. The second is for anyone told to go easy on fluids — if your doctor has told you to limit your liquids, ask what you should do when it is very hot.
That second one matters more than its length suggests. Every cooling instruction on every page above ends in fluids, and a person with a fluid limit already holds an instruction that outranks all of them, given by someone with their chart open. Fluids that will not stay down at all are a different emergency with a different list. The question is not whether to keep the limit. It is what the limit becomes on a very hot day, and one person can answer that.
Where the next walk goes
- Tonight: NIA's instruction for heat exhaustion is to rest in a cool place and get plenty of fluids, unless you have been told to limit them. Its cooling steps — cool cloths, a cool bath or shower, fans — belong to its heat stroke entry, where they come after seeking medical help right away.
- Go to a doctor or an emergency room for the headache or the nausea, and for any confusion or dizziness. NIA says those four could be a sign of a heat-related illness and to go find out if you need treatment; the trigger is NIA's, not a threshold invented here.
- Call 911 for confusion, slurred speech, fainting or loss of consciousness in heat, and stay with anyone showing them until help arrives.
- Move the walk out of the afternoon. NIA's tip is to avoid outdoor exercise and other physical activity when it is very hot, and find somewhere to be active while staying cool indoors.
- Check the heat index in addition to the thermometer. NIA describes it as considering both air temperature and humidity to say what the temperature actually feels like.
- Put the two questions above to the prescriber at the next contact, and put them before the next stretch of hot weather rather than after it.
A walk in the heat is not a fitness test you failed. It was an afternoon with three things stacked on it — the weather, the water pill and a week of not much food or drink — and which of the two illnesses this was is not something the lists settle, since they overlap. Of the three, the afternoon is the one that moves.
