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Common Child Emergencies: Fever, Croup, Dehydration, and When to Call for Help
The numbers that actually change the decision, from the 100.4 rule for newborns to the moment stridor means 911.
Logan Pierce
August 21, 2026
Key points
Under 3 months old, a rectal temperature of 100.4 F (38 C) means call the pediatrician immediately, even with no other symptoms.
In older kids the number matters less than how the child looks, acts, and breathes.
Stridor at rest, blue lips, or drooling with croup is a 911 call, not a wait-and-see.
Fewer than 6 wet diapers a day is the dehydration marker most parents miss.
For any suspected poisoning, call Poison Control at 1-800-222-1222. Do not induce vomiting.
Most nights with a sick kid, the hard part is not the treatment. It is the decision. Do you call, do you drive, or do you wait until morning.
The common child emergencies are a short list, and the real decision thresholds are published, specific, and free to look up. This is that list, with the numbers the American Academy of Pediatrics actually uses and the moments that mean call 911 now.
One thing first, plainly. I write this newsletter under the name Logan Pierce. I am not a doctor, a nurse, or an EMT. What follows is decision support so you can make a faster, calmer call. It is not a substitute for care, and it does not replace your pediatrician or a 911 dispatcher.
What are the most common child emergencies parents actually face?
Six things account for most of the frightening nights: fever, croup, dehydration from vomiting or diarrhea, allergic reactions, head bumps, and swallowed poisons. Choking and burns round out the list, and I covered those separately. The exact numbers for those are in the guide to first aid for common household injuries.
What these 6 have in common is that each one has a threshold. Below it, you manage at home and call in the morning. Above it, you call now. Knowing where the line sits is most of the job. Here is the part most guides skip: your own read on the child is a legitimate data point. Every one of the sources below eventually says a version of "if your child looks or acts very ill, call." That is not a hedge. Parents notice changes a chart cannot.
When is a fever in a child an emergency?
It depends almost entirely on age, and the youngest kids have the strictest rule. According to the American Academy of Pediatrics, a rectal temperature of 100.4 F (38 C) or higher counts as a fever, and the thresholds run like this:
3 months or younger: 100.4 F (38 C) rectal. Call your pediatrician immediately, "even if your baby shows no other signs or symptoms." This one is not negotiable and not a wait-until-morning call.
3 to 6 months: notify the doctor at 101 F (38.3 C) or greater.
Older than 6 months: notify the doctor at 103 F (39.4 C) or higher.
Rectal readings are the most reliable and accurate in infants, and the AAP advises against ear thermometers in babies under 6 months because the ear canal is too small. Use a digital rectal thermometer for the under-3-months group. That is the number the pediatrician will ask for.
Call 911 for a seizure with fever that lasts beyond 15 minutes or comes with difficulty breathing. Febrile seizures happen most often between 6 months and 5 years, and short ones are frightening but usually not dangerous.
Why does how the child looks matter more than the number on the thermometer?
Because past infancy, the height of the fever tracks poorly with how sick the child actually is. A cheerful 4-year-old at 103 F is usually in better shape than a limp one at 101 F. The AAP's own guidance is that "not every fever needs to be treated," and that you should call the doctor if your child "looks very ill, is unusually drowsy or is very fussy," or still "acts sick" once the fever comes down.
Watch these instead of the digits: how they breathe, whether they are drinking, whether they respond to you normally, whether the skin is mottled or the lips are dry, and whether they perk up at all when the fever drops.
Two things the AAP says to stop doing. Alcohol baths, ice packs, and sponging "are no longer recommended" and "can actually have adverse effects." And for children under 2, get the acetaminophen or ibuprofen dose from your pediatrician or pharmacist rather than guessing from the box. Pediatric dosing is weight-based, which is one more reason to keep a current one-page emergency medical sheet for each child with their weight written on it.
With croup, judge by the breathing, not by whether the steam seemed to help.
What is croup, and when does stridor mean you should call 911?
Croup is swelling of the voice box and windpipe that narrows a child's airway, and stridor while the child is resting is an emergency. The AAP describes croup as "a swelling of the voice box (larynx) and windpipe (trachea)" that most often hits children between 3 months and 5 years, peaking in fall and winter.
You will know it by sound. The cough is harsh and barking, like a seal. The voice goes hoarse. Stridor is "a coarse musical sound each time they breathe in," and it is the one that matters.
Call 911 or go to the emergency department if the child has any of these:
Stridor while resting, not just while crying or coughing
A whistling sound that gets louder with each breath
Struggling visibly to catch their breath
Bluish lips or fingernails
Cannot speak or make sounds because of the effort of breathing
Drooling, or extreme difficulty swallowing saliva
Here is the honest limit that surprises people. The steam-in-the-bathroom trick and the cool-night-air trick are both traditions, not treatments. The AAP notes that while "some parents may find that this helps improve breathing, there are no studies to prove that inhaling steam in a bathroom is effective," and says the same about cool night air. Keep the child calm and upright, treat the fever, keep fluids going, and judge by the breathing rather than by whether the steam seemed to help.
Small amounts every few minutes beat a full cup that comes straight back up.
How can you tell if a child is dehydrated, and what should you give them?
Count wet diapers or trips to the bathroom first, because output drops before anything else looks wrong. The AAP lists these as the early warning signs, and says to notify the pediatrician immediately if any of them develop:
Plays less than usual
Urinates less often, and for infants, fewer than 6 wet diapers a day
Parched, dry mouth
Fewer tears when crying
Sunken soft spot on the head of an infant or toddler
Severe dehydration adds sunken eyes, wrinkled skin, cool or discolored hands and feet, a child who is either very fussy or excessively sleepy, and urination down to only 1 or 2 times a day. That combination is an emergency department trip, not a phone call.
On what to give, the AAP's rehydration guidance splits by age:
6 months to 1 year: undiluted breast milk or formula. If that is not staying down, use a commercial oral rehydration solution. Do not use plain water.
1 year and older: commercial oral rehydration solutions, including the popsicle form, or apple juice or a sports drink cut 50/50 with water.
Give it in small amounts every few minutes rather than in cupfuls, aiming for at least 1 ounce (30 ml) per hour, and limit solid food for the first 24 hours or so. If the child will not sip, use a medicine cup, an oral syringe, or a teaspoon.
The mistake I see most often is plain water for a vomiting infant, or full-strength juice or sports drink for a toddler. Water alone lacks the salts an infant needs. Undiluted juice and sports drinks carry enough sugar to make diarrhea worse. Dilute or use a proper rehydration solution.
What is the difference between an allergic reaction and anaphylaxis in a child?
Anaphylaxis involves breathing, circulation, or two or more body systems at once, and it is a 911 emergency. The AAP calls it "a rapid and severe allergic reaction" that can start "within minutes or several hours after exposure to an allergy trigger."
Hives alone on one arm after a new food is usually a mild reaction. Any of the following is anaphylaxis until proven otherwise:
Shortness of breath, wheezing, coughing, or chest tightness
Trouble breathing or swallowing
Swelling of the lips or tongue
Widespread hives, redness, or pale or bluish skin
Weak pulse, dizziness, or fainting
Vomiting or diarrhea, if severe or combined with the above
A feeling of "doom," confusion, drowsiness, or agitation
In infants, watch for irritability, sudden drooling, and unusual sleepiness.
The action is the same every time. Give epinephrine immediately into the muscle of the outer thigh, note the time it was given, and call 911. The AAP is blunt on the point people get wrong: "never use other medicine in place of epinephrine." An antihistamine does not treat anaphylaxis. It treats the itching while the reaction keeps going. Children at risk should carry at least 2 doses at all times, because one is sometimes not enough. That second dose is one of the things worth building into an emergency kit a child can carry and open on their own.
When does a child's head bump need a CT scan or an ER visit?
Call 911 if the child loses consciousness. Short of that, the AAP lists these as the signs that need medical attention right away:
A constant headache, especially one that is getting worse
Slurred speech or confusion
Vomiting more than 2 or 3 times
Dizziness that keeps happening or will not go away
Extreme irritability or other abnormal behavior
Stumbling or difficulty walking, weakness in an arm or leg
Blood or watery fluid from the nose or ears
Difficulty waking up or excessive sleepiness
Unequal pupil size, double vision, or blurry vision
Seizures
CDC's HEADS UP program adds a matching danger list for concussion, including a child who cannot recognize people or places, repeated nausea or vomiting, and increasing confusion, restlessness, or agitation.
Not every bump needs imaging, and this is where the numbers help. The AAP notes that "about half of children in emergency rooms with head injuries get CT scans. But one in three of the CT scans aren't necessary." CT uses radiation, and children carry more risk from it because their brains are still developing. The mechanisms that do raise concern are falls from 3 feet or more, falls down 5 or more stairs, bike crashes without a helmet, and motor vehicle accidents.
For a minor bump with none of the danger signs, the AAP says a responsible adult should stay with the child for the first 24 hours and check every 2 to 3 hours that they move normally, wake normally, and respond normally. And to settle the oldest myth in parenting: "It is okay for your child to go to sleep." Use acetaminophen for pain unless your pediatrician says otherwise.
What should you do if a child swallows something poisonous?
Call Poison Control at 1-800-222-1222 right away, and do not make the child vomit. Poison Control is explicit: "Do not induce vomiting. Ipecac syrup is no longer recommended." The line is free, confidential, and staffed 24 hours a day, and most cases are handled at home over the phone.
Call 911 first instead if the child has collapsed, is having a seizure, is having trouble breathing, or is unresponsive.
The first aid depends on the route:
Swallowed: call Poison Control. Give small amounts of water or milk only if the substance is caustic and the child is awake and able to swallow.
In the eye: act immediately. Remove contact lenses, then irrigate with lots of room temperature water for at least 15 to 20 minutes. For a child, let water from a faucet run across the eye rather than pouring it directly. Poison Control warns that "every second matters and a delay could result in loss of sight."
On the skin: remove contaminated clothing first, then rinse with lots of room temperature running water for at least 15 minutes.
Inhaled: move to fresh air immediately, and stay out of the fumes yourself.
Why the vomiting advice reversed: a 2004 expert panel found "no evidence from clinical studies that ipecac improves the outcome of poisoned patients," and the American Academy of Pediatrics issued a policy in 2003 recommending against routine home use. Ipecac could also make things worse with caustic chemicals, and a vomiting child cannot keep down the medicine that actually treats the poisoning. It is no longer manufactured. If you still have a bottle in an old first aid kit, throw it out.
Save 1-800-222-1222 in every phone in the house tonight. It takes 20 seconds and it is the single highest-value thing in this article.
When to get professional help
Everything above is decision support, not medical care, and I am not a medical professional. Your pediatrician's after-hours line exists for exactly these questions, and using it is not an imposition.
Call 911 immediately for any of these:
The child is not breathing, is struggling to breathe, or has blue or gray lips
Stridor at rest, or the child cannot speak or swallow their own saliva
Signs of anaphylaxis. Give epinephrine first, then call
Loss of consciousness after a head injury
A seizure lasting beyond 15 minutes, or any seizure with difficulty breathing
The child is unresponsive, limp, or will not wake up
Poisoning with collapse, seizure, or trouble breathing
Call the pediatrician now, not in the morning, for: any fever of 100.4 F (38 C) in a baby 3 months or younger, dehydration warning signs, vomiting more than 2 or 3 times after a head bump, a fever that comes back after several days, or a child who still acts sick after the fever has come down.
Call Poison Control at 1-800-222-1222 for any suspected poisoning, medication mix-up, or overdose, at any hour, before you do anything else.
Frequently asked questions
What temperature is an emergency for a baby?
A rectal temperature of 100.4 F (38 C) or higher in a baby 3 months or younger. The AAP says to call the pediatrician immediately at that number even if the baby has no other symptoms, because young infants can be seriously ill without looking it. For 3 to 6 months the threshold is 101 F, and for over 6 months it is 103 F.
How do I know if my child's cough is croup?
Croup sounds like a seal barking, and the voice goes hoarse with it. It usually starts like a cold and worsens at night, mostly in children between 3 months and 5 years. The cough itself is not the emergency. Stridor at rest, blue lips, drooling, or visible struggle to breathe are, and those mean 911.
How long can a child go without peeing before I should worry?
For infants, fewer than 6 wet diapers in a day is the AAP's warning threshold, and 1 to 2 wet diapers a day signals severe dehydration. For older children, no urination in 8 hours combined with a dry mouth, no tears, and unusual sleepiness warrants a same-day call. Output drops before the other signs show up.
Do I need to keep my child awake after a head injury?
No. The AAP states that "it is okay for your child to go to sleep" after a minor head injury. What matters is that a responsible adult stays with them for 24 hours and checks every 2 to 3 hours that they wake, move, and respond normally. Anything abnormal on those checks means call the doctor.
Should I make my child throw up if they swallow something poisonous?
No. Poison Control states plainly that you should not induce vomiting and that ipecac syrup is no longer recommended. Call 1-800-222-1222 immediately instead. Vomiting can cause more damage on the way back up with caustic substances, and it can prevent the child from keeping down the treatment they actually need.
Can I give an antihistamine instead of an epinephrine auto-injector?
No. The AAP's instruction is to "never use other medicine in place of epinephrine." Antihistamines can ease itching and hives but do nothing for the airway swelling or the drop in blood pressure that make anaphylaxis dangerous. Give epinephrine into the outer thigh, note the time, then call 911.
Print it, put it on the fridge, and save the Poison Control number in every phone.
Print the thresholds, put Poison Control in every phone, and know where the epinephrine lives if your household needs it. None of this makes a bad night easy. It just means the decision is already made before you have to make it at 3 a.m.
You never know, but you can always be ready.