When a child with fever and vomiting can’t drink: how to use oral rehydration solution and when to see a doctor

Hello. I am Shunichi Gamo, MD, PhD, a board-certified pulmonologist and the director of Sendai International Airport North Clinic.

When your child has a fever and keeps vomiting, they may not be able to take even water or tea. You may worry about dehydration (when the body does not have enough water and salt). Oral rehydration solution, or ORS, is a drink made to replace lost water and salt by mouth. How to give it, and whether an IV drip (giving fluids directly into a vein) is needed, can be hard to decide at home.

This article is for parents of children from infancy through about the elementary-school years. It explains how to give fluids at home and the signs that mean you should seek care quickly. It is based on clinical trials and review articles (papers that summarize the research on a topic) about acute gastroenteritis in children. Acute gastroenteritis is an illness that starts suddenly, mainly with diarrhea, and may come with nausea, vomiting, fever or stomach pain. For the practical steps at home, it also draws on a UK guideline for children under 5 (NICE CG84). This information may not apply in the same way to adults.

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Can you spot dehydration at home when a child with fever and vomiting can’t drink?

You cannot accurately judge at home how dehydrated your child is; a doctor needs to examine them. A US review article (on acute gastroenteritis in children) states that a physical exam is the best way to assess how dehydrated a child is. [1] Exam findings have been reported to predict dehydration better in combination than on their own. [2]

Dehydration scales (scoring charts that rate how severe dehydration is based on what is seen during the exam) are also used in exams, but not every scale works equally well. In one study, two of the scoring charts used in exams were “fair” at predicting dehydration. The WHO scoring chart and the doctor’s overall impression could not be shown to help predict dehydration. [3] Parents do not need to give a score. What matters is noticing how your child differs from usual and telling the medical staff.

The UK NICE guideline (for children under 5) lists the following as signs of dehydration. For home care: NICE (UK)

• Looks unwell and seems to be getting worse
• Responds differently from usual, for example, is irritable or limp and listless
• Is passing less urine
• Looks pale or blotchy, or has cold hands and feet

What to watch	Example notes to share at the visit
How much they drank	What, at what time, and how much they were able to drink
Vomiting	How many times, and whether they vomited right after drinking
Urine	How often and how much compared with usual, and the time they last peed
General condition	Mood, how they respond, skin color, whether hands and feet are cold

Before a visit or a phone consultation, write these four items down with the times. If you can, also note the time your child last passed urine.

How do you give a child oral rehydration solution? Will water or juice do instead?

When you use ORS, give small amounts often. A US review article (on children) says that giving fluids by mouth is the main treatment for mild dehydration, and recommends ORS for moderate dehydration. [1] The UK NICE guideline (for children under 5) also advises giving ORS to dehydrated children in small amounts, often, and preparing it exactly as the package directions say.

There are different types of ORS. The ones used today are low-osmolarity products, with lower levels of salt and sugar. A systematic review (a study that gathers several studies on the same topic and combines their results statistically) looked at acute diarrhea in children. It found that low-osmolarity ORS led to fewer switches to an IV drip and less vomiting than the older standard WHO solution. [4] This compared one ORS with another; it did not compare ORS with water or juice.

For diluted apple juice, one trial studied children aged 6 to 60 months who had mild gastroenteritis with little or no dehydration. Children given diluted apple juice and their preferred drinks had fewer treatment failures within 7 days, and fewer IV drips, than children given an electrolyte drink (a rehydration drink containing electrolytes, similar to ORS). [5] However, this trial included only children with little or no dehydration. It does not mean juice is fine for moderate or severe dehydration. The NICE guideline advises against fruit juice and carbonated drinks when preventing or treating dehydration.

Your child’s condition	Approach to drinks
Mild gastroenteritis with little or no dehydration (trial in children aged 6 to 60 months)	The group given diluted apple juice, followed by their preferred drinks, had fewer treatment failures [5]
Children with dehydration (US review article, UK NICE)	The US review article says fluids by mouth are the main treatment for mild dehydration, and recommends ORS for moderate dehydration [1]. ORS should be given in small amounts, often (UK NICE guideline, for children under 5)
Children who refuse ORS (UK NICE, under 5)	If there are no warning signs, consider also giving their usual drinks (breast milk, formula or water). Avoid juice and carbonated drinks (UK NICE guideline, for children under 5)

How much to give each time, and how often, depends on your child’s age and weight. Ask your regular doctor for specific amounts ahead of time.

Giving oral rehydration solution to a vomiting child: is it OK to continue breast milk, formula and food?

Even when you use ORS for a vomiting child, keep breastfeeding. The UK NICE guideline (for children under 5) advises that children without dehydration should continue breast milk or formula and be encouraged to drink fluids. During treatment for dehydration, it says to keep breastfeeding while also giving ORS.

As for solid food, the same guideline says not to give it during rehydration treatment, and to go back to the usual diet once rehydration is complete. After rehydration, it says to restart formula right away without diluting it, and to avoid fruit juice and carbonated drinks until the diarrhea stops. These are UK recommendations. Medical facilities in Japan may give different advice.

If you are unsure when to restart food or how to move forward with baby food, ask your regular doctor at the visit.

If your child vomits up oral rehydration solution, do they need an IV drip?

Vomiting does not always mean your child will need an IV drip right away. A US review article (on children) says the anti-nausea medicine ondansetron may be prescribed when needed, to prevent vomiting and make ORS easier to drink. [1] Anti-nausea medicine is prescribed when a doctor decides after an exam that it is needed. Do not give medicine you have at home on your own judgment. If you have already given any medicine, tell the doctor its name.

An IV drip is recommended for children who do not improve with fluids by mouth and anti-nausea medicine, and for children with severe dehydration. Severe dehydration means there are signs of shock, or the child has lost fluid equal to more than 10% of their body weight. (Shock is a dangerous state in which blood circulation cannot be maintained and not enough blood reaches the whole body.) [1]

One trial compared fluids by mouth with an IV drip in infants and young children (aged 8 weeks to 3 years) with moderate dehydration. Under medical supervision, fluids by mouth were no less effective than an IV drip. [6] A review of 17 trials (on dehydration from gastroenteritis in children) also found that fluids by mouth had slightly more treatment failures. Still, there was no large clinical difference from an IV drip, and hospital stays tended to be shorter with fluids by mouth. [7] However, these results are for children who could drink. They do not mean that an IV drip is unnecessary when a child keeps vomiting and cannot drink.

What you see at home	What to discuss at the visit
Vomits ORS even when given in small amounts	Whether anti-nausea medicine should be considered
Rehydration is not working even with anti-nausea medicine (the US review article is on children)	Hospital admission and an IV drip are recommended for children who do not improve with fluids by mouth and anti-nausea medicine (US review article) [1]. Ask the doctor whether this is needed
Passing less urine, and it has been a while since they last peed	Have the doctor check whether dehydration is getting worse

Write down when your child vomited and what and how much they drank just before, and tell the doctor in order at the visit.

How long do vomiting and diarrhea last in children, and what are the signs of getting worse?

According to the UK NICE guideline (for children under 5), vomiting from gastroenteritis usually lasts 1 to 2 days and in most cases stops within 3 days. Diarrhea usually lasts 5 to 7 days and in most cases stops within 2 weeks. If symptoms go on longer than this, the guideline advises getting medical advice.

A study in the Netherlands followed 359 children for 7 days after they were seen at out-of-hours primary care. In most children, symptoms eased within 5 days. However, 31 children got worse and needed referral or hospital admission. [8] The children who got worse tended to vomit more often, both at the visit and later on. The study states that how often a child vomits matters more than how long the vomiting lasts in predicting who will get worse. [8]

The UK NICE guideline lists signs of dehydration that mean parents should contact a health professional. These signs are looking more and more unwell, a change in how the child responds, passing less urine, pale or blotchy skin, and cold hands and feet. It also advises contacting them if the child refuses ORS or keeps vomiting.

If your child seems confused or drowsy, looks pale with cold hands and feet, or anything else makes you very worried, do not hesitate to go to the emergency department, even at night.

Fever and vomiting in a child: could it be an illness other than gastroenteritis?

The UK NICE guideline (for children under 5) lists signs that suggest an illness other than gastroenteritis. These include blood or mucus in the stool, green vomit, severe stomach pain or pain in one spot, and a swollen belly. A stiff neck, a rash that does not fade, or fast breathing also suggest a different illness.

In particular, when there is stomach pain, appendicitis (inflammation of the appendix) also needs to be considered. In preschool children it is especially common for appendicitis not to show its typical signs, so it cannot be ruled out just because the child has no pain in the lower right belly. [9]

Make a note of where it hurts, whether the painful spot has moved, whether there is blood in the stool, and whether the vomit is green, and tell the doctor.

Seeing a doctor for a child’s fever and vomiting: what should you tell them?

When you see a doctor for your child’s fever and vomiting, it helps the exam go smoothly if you share six points, with times or numbers of days. The six points are how much they drank, urine, vomiting, stool and fever, stomach pain, and any ongoing conditions and medicines. How much they drank, their urine and their vomiting help the doctor judge how dehydrated they are. [1] It also helps to tell the doctor whether there is blood in the stool and how many days the fever has lasted.

What to tell the doctor	Example notes
How much they drank	ORS by the teaspoon, several times; half a cup in total since noon
Urine	Last peed at 7 a.m.; less than usual
Vomiting	4 times since noon; vomits right after drinking
Stool and fever	Watery diarrhea 3 times, no blood; fever on day 2
Stomach pain	Pain around the belly button; the spot has not moved
Ongoing conditions and medicines	None, or yes (name of the condition and the medicines)

At the end of the visit, check two things: “Is it OK to keep giving fluids by mouth?” and “What should we do next if they can’t drink well?”

Summary

• A doctor assesses how dehydrated a child is during an exam. At home, write down how much they drank, their urine, vomiting and general condition, with the times.
• Give ORS in small amounts, often (UK NICE guideline, for children under 5). Keep breastfeeding.
• If vomiting keeps rehydration from working, ask a doctor whether anti-nausea medicine or an IV drip is needed.
• If your child is limp and listless, is passing less urine, or looks pale with cold hands and feet, see a doctor soon.

Frequently asked questions

When should I start using oral rehydration solution?

A US review article recommends ORS for children with acute gastroenteritis who have moderate dehydration. [1] A doctor assesses how dehydrated your child is during an exam. Note down how much they drank and any change in their urine, take your child to see a doctor, and ask whether it is time to switch to ORS.

What should I do if my child refuses to drink ORS?

The UK NICE guideline (for children under 5) advises talking to a health professional if a child refuses to drink or keeps vomiting. If there are no warning signs, also giving their usual drinks may be an option. Check at the visit which approach suits your child.

If vomiting continues, might my child need an IV drip?

A US review article recommends hospital admission and an IV drip for children who do not improve with fluids by mouth and anti-nausea medicine, and for children with severe dehydration. [1] If your child keeps vomiting so that rehydration is not working even with small sips, or is clearly passing less urine, see a doctor soon. Tell the doctor how many times they vomited and when they last passed urine.

If my child has a fever and stomach pain, can I assume it is gastroenteritis?

When a child has a fever and stomach pain, appendicitis also needs to be considered. In preschool children it is especially common for appendicitis not to show its typical signs, and it cannot be ruled out even if the child has no pain in the lower right belly. [9] Tell the doctor where it hurts, how that has changed, and whether your child has an appetite, along with how rehydration is going.

Disclaimer

This article provides general medical information. It does not replace an examination, diagnosis or treatment by a doctor. The content is based on medical knowledge at the time of publication, but the right approach differs with each patient’s condition and background.

If you are worried about your symptoms, please talk to your regular doctor or a specialist medical facility.

References

1. Hartman S, Brown E, Loomis E, Russell HA. “Gastroenteritis in Children.” Am Fam Physician, 2019 Feb 01; 99(3): 159-165. PMID: 30702253
2. Steiner MJ, DeWalt DA, Byerley JS. “Is this child dehydrated?.” JAMA, 2004 Jun 09; 291(22): 2746-54. DOI: 10.1001/jama.291.22.2746 PMID: 15187057
3. Jauregui J, Nelson D, Choo E, Stearns B, Levine AC, Liebmann O, et al. “External validation and comparison of three pediatric clinical dehydration scales.” PLoS One, 2014; 9(5): e95739. DOI: 10.1371/journal.pone.0095739 PMID: 24788134
4. Hahn S, Kim S, Garner P. “Reduced osmolarity oral rehydration solution for treating dehydration caused by acute diarrhoea in children.” Cochrane Database Syst Rev, 2002(1): CD002847. DOI: 10.1002/14651858.CD002847 PMID: 11869639
5. Freedman SB, Willan AR, Boutis K, Schuh S. “Effect of Dilute Apple Juice and Preferred Fluids vs Electrolyte Maintenance Solution on Treatment Failure Among Children With Mild Gastroenteritis: A Randomized Clinical Trial.” JAMA, 2016 May 10; 315(18): 1966-74. DOI: 10.1001/jama.2016.5352 PMID: 27131100
6. Spandorfer PR, Alessandrini EA, Joffe MD, Localio R, Shaw KN. “Oral versus intravenous rehydration of moderately dehydrated children: a randomized, controlled trial.” Pediatrics, 2005 Feb; 115(2): 295-301. DOI: 10.1542/peds.2004-0245 PMID: 15687435
7. Hartling L, Bellemare S, Wiebe N, Russell K, Klassen TP, Craig W. “Oral versus intravenous rehydration for treating dehydration due to gastroenteritis in children.” Cochrane Database Syst Rev, 2006 Jul 19; 2006(3): CD004390. DOI: 10.1002/14651858.CD004390.pub2 PMID: 16856044
8. Weghorst AAH, Bonvanie IJ, Holtman GA, de Boer MR, Berger MY. “Course of uncomplicated acute gastroenteritis in children presenting to out-of-hours primary care.” BMC Prim Care, 2022 May 24; 23(1): 125. DOI: 10.1186/s12875-022-01739-2 PMID: 35606695
9. Stringer MD. “Acute appendicitis.” J Paediatr Child Health, 2017 Nov; 53(11): 1071-1076. DOI: 10.1111/jpc.13737 PMID: 29044790