What to eat during gastroenteritis: what science really says
More than 21 million cases of acute gastroenteritis occur each year in France, according to Eurosurveillance data. Yet, when faced with nausea and diarrhea, most people don't know exactly what to eat — or what to avoid — to truly speed up their recovery. Some common reflexes are even counterproductive: for instance, the use of activated charcoal against nausea is regulatory prohibited as a digestive health claim in this context under European regulations — a reality that few pharmacies clearly display.
Gastroenteritis nutrition remains one of the most misunderstood topics by the general public, and it's precisely this gap between inherited reflexes and current data that this article aims to correct. This article is for informational purposes and does not replace the advice of a healthcare professional.
The good news: three pillars now have solid scientific support. First, strategic rehydration — not just drinking water, but precisely replenishing lost electrolytes. Next, targeted and progressive food reintroduction, far from the myth of total diet restriction. Finally, restoration of the intestinal microbiome, what we call the intestinal flora — the ecosystem of billions of bacteria that line your intestine and that gastroenteritis can profoundly disrupt. These are the three approaches, based on clinical studies and expert recommendations, that the following sections will detail.
The essentials about gastroenteritis
- In France, gastroenteritis affects approximately 21 million people each year, with a typical recovery period of 1 to 7 days for most healthy adults (Harvard Health).
- Rehydration with oral rehydration solutions (ORS) constitutes the fundamental pillar of healing: ORS have reduced diarrhea mortality by 93% worldwide (Child Health Task Force / IJE).
- Norovirus, the most common causative agent, requires only 10 to 100 viral particles to cause infection — one of the lowest infectious thresholds known in virology.
- According to a meta-analysis published in BMJ Open (2021), probiotics can reduce the duration of diarrheal episodes, although the magnitude of the effect varies depending on strains and populations studied.
- A study published in the World Journal of Gastroenterology showed that humic acid supplementation leads to an increase of more than 30% in colonic microbiota concentration in human subjects.
Gastroenteritis: when 100 invisible particles are enough to trigger everything
Gastroenteritis is an acute inflammation of the stomach and intestines — brutal, sudden, and in the vast majority of cases viral in origin. Norovirus is the main culprit, followed by rotavirus, especially feared in young children. The symptoms arrive together and without warning: diarrhea, vomiting, cramping abdominal pain, sometimes fever.
What makes norovirus particularly difficult to contain is its infectious threshold: according to data from the European Centre for Disease Prevention and Control (ECDC), between 10 and 100 viral particles are sufficient to infect a human being. To put this number in perspective: a sick person can excrete several billion particles per gram of stool. Proper hygiene reduces the risk but doesn't eliminate it — which explains why epidemics spread so easily in daycare centers, nursing homes, and hospitals.
Some populations need to be extra vigilant: infants, elderly people, and pregnant women are more exposed to complications, particularly severe dehydration.
For a healthy adult, recovery is spontaneous within 1 to 7 days. But the absence of active treatment is not without risk: repeated fluid losses quickly lead to dehydration, which remains the leading cause of complications. And the end of symptoms does not mean the end of contagiousness — according to CDC data, a recovered person can continue to transmit norovirus for up to two weeks after the clinical disappearance of symptoms. That's why a well-managed recovery — not just "waiting it out" — makes a real difference.
This article is for informational purposes. Consult a healthcare professional for personalized advice.
BMJ Open
Probiotics for the prevention of antibiotic-associated diarrhoea: a systematic review and meta-analysis
A study published in BMJ Open (2021) showed that probiotics significantly reduced the incidence of antibiotic-associated diarrhea in adults — suggesting a potential role in modulating the disrupted intestinal microbiota, a mechanism common to infectious diarrhea and acute gastroenteritis.
PubMed →Gastroenteritis rehydration: the first pillar, before everything else
When gastroenteritis strikes, the body loses water and minerals at a rate that is almost always underestimated. Each episode of diarrhea or vomiting carries away sodium, potassium, and chloride — these electrolytes that allow your cells to maintain their internal tension, like air in a tire. Without them, cells deflate and stop functioning normally. This is what doctors call dehydration, and in severe forms, it can become deadly within hours.
One figure alone summarizes the stakes: the introduction of oral rehydration solutions (ORS) worldwide has reduced diarrhea mortality in children by 93% — according to an epidemiological analysis published in the International Journal of Epidemiology (Child Health Task Force, 2010). Not a drug. Not an antibiotic. Water, salt, and sugar, in the right proportions.
The key to this effectiveness lies in a very precise mechanism: the intestine has transporters capable of absorbing sodium and glucose simultaneously — and water follows this movement, as if sucked by a pump. This is the principle of sodium-glucose co-transport, and ORS are formulated to exploit it to the maximum. Reduced-osmolarity ORS — the formula recommended by WHO since 2003 — reduce the duration of diarrhea by 22% compared to the old standard formula, according to a review published in PMC on WHO recommendations for acute gastroenteritis.
If you don't have ORS on hand, several natural options rich in electrolytes can complement hydration: unsweetened coconut water (rich in natural electrolytes), clear broths (minerals), and chamomile or mint teas, recognized for their soothing effect on the digestive system while contributing to fluid intake.
The rule is simple: before thinking about eating, before taking anything else, drink. In small sips, every five to ten minutes, to avoid triggering new vomiting. Rehydration is not a detail — it's the foundation on which all the rest of the recovery rests. This article is for informational purposes. Consult a healthcare professional for personalized advice.
Frontiers in Immunology
Probiotics fortify intestinal barrier function: a systematic review and meta-analysis of randomized trials
This meta-analysis of randomized trials published in Frontiers in Immunology (2023) showed that probiotics improved intestinal barrier function, inflammatory markers, and microbiota composition — mechanisms directly relevant to post-gastroenteritis recovery, during which tight junctions and mucosal integrity are compromised by viral infection.
PubMed →World Journal of Gastroenterology
Impact of humic acids on the colonic microbiome in healthy volunteers
A study published in the World Journal of Gastroenterology (2016) showed that orally administered humic acids increased the overall concentration of the colonic microbiota by more than 30% in healthy volunteers (p < 0.001), by stimulating the growth of 24 of the 35 bacterial groups studied. These results suggest that humic acids could act as a natural microbial fertilizer, distinct from classic probiotics, by supporting the diversity and density of the intestinal microbiome.
PubMed →Three recovery levers: mechanisms and comparative evidence
| Main mechanism | Level of evidence | Recommended timing | For whom? | |
|---|---|---|---|---|
| Rehydration (ORS) | Sodium-glucose co-transport, compensation for electrolyte losses | High — WHO recommendation, documented mortality reduction | From the first symptoms | All — absolute priority, no exception |
| Probiotics | Microbiota restoration, strengthening of the intestinal barrier | Moderate-high — meta-analyses BMJ Open 2021 and Frontiers in Immunology 2023 | During and after the acute episode | Adults, children (validated strains), post-antibiotic subjects |
| Humic acids | Stimulation of colonic microbiota growth (suggests +30% in WJG 2016 study) | Preliminary — unique human study, indicates a microbiota benefit to be confirmed | In the microbiota recovery phase, after the acute episode | Adults, mainly post-intense diarrhea |
What to eat during gastroenteritis: the choice of each food has a reason
When your digestive tract is in crisis, every bite counts double. The five foods that follow are not chosen by tradition — each has a precise physiological justification.
Bananas
Bananas are rich in potassium, a mineral that contributes to normal muscle function and normal functioning of the nervous system — two functions directly compromised by electrolyte losses related to vomiting and diarrhea. Potassium also contributes to the maintenance of normal blood pressure, which makes sense when dehydration causes blood volume to drop.
White rice
White rice is a refined starch with rapid digestion: it provides easily assimilated energy without stressing an already irritated intestine. Its low fiber content helps slow transit and make stools more consistent — exactly what an intestine in hypermotility needs.
Unsweetened applesauce
Applesauce provides soluble fibers — notably pectin — which act as a gel in the intestine, capturing excess water in the colon and gradually normalizing transit. Without added sugar, it avoids the osmotic effect that would worsen diarrhea.
White bread / toast
Toasted white bread offers a neutral and non-irritating energy substrate. Its partially retrograded starch — transformed by cooking and then cooling — is slightly more resistant to rapid digestion, which stabilizes blood sugar without causing an insulin spike that could increase fatigue.
Clear broths
A clear vegetable or chicken broth serves two functions simultaneously: it rehydrates and provides sodium, an essential electrolyte for intestinal cells to efficiently reabsorb water. It's the natural complement to the oral rehydration protocol described earlier in this article.
This article is for informational purposes. Consult a healthcare professional for personalized advice.
Some foods worsen symptoms by irritating the intestinal mucosa or increasing water loss — avoid them until symptoms completely resolve:
- Fatty and fried foods: slow gastric emptying and promote nausea.
- Dairy products (lactose): infection temporarily reduces intestinal lactase, making lactose poorly digested and diarrheogenic.
- Spicy foods: directly irritate the already fragile digestive mucosa.
- Caffeine and alcohol: diuretic and pro-inflammatory effects that increase dehydration.
- Foods very rich in fiber and raw vegetables: accelerate transit and stress an intestine unable to process them effectively in the acute phase.
- Very sweet drinks and foods: cause osmotic diarrhea — excess sugar attracts water into the intestine, increasing stool volume and worsening fluid loss.
How to recover from gastroenteritis: phase-by-phase protocol
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Prioritize rehydration during the first 24 hours
During the acute phase, the sole objective is to compensate for fluid losses caused by vomiting and diarrhea. All solid food should be suspended until vomiting subsides. Prioritize oral rehydration solutions (ORS), which contain a precise mixture of mineral salts and glucose designed to optimize water absorption by the intestine — a mechanism validated by WHO, responsible for a 93% reduction in dehydration mortality in documented clinical contexts. Alternately, clear lightly salted broths and still water consumed in frequent small sips (50–100 ml every 15 minutes) help maintain fluid intake without stressing a weakened digestive system.
Individual results may vary depending on the degree of dehydration and the causative pathogen.
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Gradually reintroduce solid foods (D2–D3)
As soon as vomiting becomes less frequent and digestive tolerance improves — usually from the second day — reintroduce solid foods in very small portions, distributed over 5 to 6 daily intakes. Opt for low-residue and easily digestible foods: white rice cooked in water, unbuttered toast, unsweetened applesauce, and bananas. Bananas are rich in potassium and help restore electrolytes lost due to vomiting and diarrhea. Avoid fatty foods, dairy products (due to the transient decrease in post-infectious lactase activity), and any spicy or acidic food likely to further irritate the intestinal mucosa.
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Gradually diversify diet (D3–D7)
From the third day, in the absence of new episodes of vomiting or intense diarrhea, reintroduce light proteins prepared by gentle methods: boiled or poached chicken, steamed or low-temperature baked fish. Gradually add cooked vegetables (carrots, zucchini, potatoes) that provide soluble fiber without overloading transit. Maintain the exclusion of lactose-rich dairy products, fried or very fatty foods, spices, and alcohol until complete normalization of stools. This diversification schedule corresponds to clinical recommendations for post-gastroenteritis dietary resumption and aims to protect a mucosa still in the healing process.
This dietary supplement does not replace a balanced and varied diet.
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Support intestinal microbiota restoration
Gastroenteritis profoundly disrupts the balance of intestinal flora. The meta-analysis published in Frontiers in Immunology (2023) demonstrated that probiotics help strengthen the intestinal barrier and restore post-infection microbial diversity. Introduce clinically validated probiotic strains (notably Lactobacillus rhamnosus GG or Saccharomyces boulardii) as soon as food tolerance allows, ideally from D2–D3. Fermented foods like kefir or plain yogurt (cautiously reintroduced in the diversification phase) can complement this intake. Moreover, preliminary studies published in the World Journal of Gastroenterology suggest that humic acids could promote the growth of good bacteria and help restore intestinal flora balance — particularly after a period of intense diarrhea. However, their use should be considered on medical advice, as clinical data remains to be consolidated.
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Identify warning signs requiring medical consultation
The vast majority of gastroenteritis resolves spontaneously within 3 to 5 days with appropriate management. Consult a doctor without delay if you observe any of the following signs:
- Persistent fever above 38.5°C for more than 48 hours
- Presence of blood in stools or vomit
- Signs of severe dehydration: no urine for more than 8 hours, very dry mouth, confusion or abnormal drowsiness
- No improvement after 3 to 5 days of appropriate management
- Symptoms in an infant, elderly person, pregnant woman, or immunocompromised patient — populations for which the consultation threshold should be lowered
These signals may indicate a complication or underlying pathology requiring urgent clinical evaluation.
Dr. Megan Rossi, Research Fellow in nutrition and gut health — King's College London — author of more than 50 scientific publications in peer-reviewed journals, specialized in the effects of probiotics, prebiotics and dietary regimens on the human microbiome. More than £3 million in dedicated gut health research funding.Dr. Megan Rossi: "Rehydration is not enough — the microbiome needs targeted support"
Dr. Megan Rossi, Research Fellow in nutrition and gut health at King's College London and author of more than 50 scientific publications in peer-reviewed journals, devotes most of her work to understanding how diet, probiotics, and prebiotics influence the human microbiome. Her research — supported by more than £3 million in dedicated funding — consistently shows that the balance of intestinal flora is not a passive state: it results from dynamic interactions between diet, microorganisms present in the colon, and the integrity of the intestinal barrier.
In the context of acute gastroenteritis, the position that her work defends is clear: rehydration, while remaining the absolute priority in the first hours, does not by itself restore the microbial ecosystem disrupted by repeated episodes of diarrhea. Her research on the effects of dietary regimens and probiotic interventions on the microbiome emphasizes that colonic bacterial diversity can be significantly reduced after a gastrointestinal infection, and that this reduction is not automatically corrected by simply returning to a normal diet. Targeted nutritional support — including documented probiotic strains and progressive food reintroduction — is necessary to support the recovery phase.
Dr. Rossi's entire research program converges toward a central recommendation: after a period of intense diarrhea, probiotics can help restore and maintain the balance of intestinal flora, which is crucial for rapid recovery. This perspective directly articulates with French epidemiological data — 21 million cases of acute gastroenteritis per year — and with recent meta-analyses that document the clinical benefit of probiotics on the duration of diarrheal episodes. For Dr. Rossi, post-infection dietary diversity, combined with an intake of beneficial microorganisms, represents an underutilized lever in current public recommendations.
Her work also reminds us of the importance of the overall dietary context in restoring the microbiome: foods like bananas, recognized for their potassium content and for which it is established that potassium contributes to the normal functioning of the nervous system and muscles, are part of a multi-dimensional recovery logic that goes beyond mere hydration compensation. For Dr. Rossi, this integrated vision — hydration, targeted nutrition, microbiome support — constitutes the foundation of optimal recovery after gastroenteritis.
Not all probiotic strains are created equal: for gastroenteritis, the most studied in clinical trials are Lactobacillus rhamnosus GG and Saccharomyces boulardii. Specific strains have shown in clinical trials a reduction in the duration of diarrheal episodes — evidence varies depending on the strain.
On the label, check three key points: the exact strain (genus, species and alphanumeric code), the number of colony-forming units (CFU) — usually expressed in billions (10⁹) — and the storage conditions (refrigeration required or thermostable formulation), which condition the viability of bacteria until the expiration date.
Activated charcoal and gastroenteritis: what science and regulations really say
Type "activated charcoal gastroenteritis" into a search engine and you'll find dozens of tips recommending you swallow it at the first symptoms. The problem: no clinical data supports this use, and European regulations don't allow it.
In Europe, the only regulated use of activated charcoal concerns the reduction of excessive flatulence after meals — and not the treatment of gastroenteritis symptoms (Regulation EC No. 432/2012). Outside of this specific indication, no health claim is authorized for this compound.
Where activated charcoal has genuine clinical anchoring is in a radically different context: emergency and toxicology services. Think of it as a single-use molecular sponge — effective only if applied directly to the spill, within minutes. A systematic review published in Clinical Toxicology (Hoegberg et al., 2021, PMID 34424785) confirmed that activated charcoal remains a relevant decontamination tool in cases of acute oral poisoning, provided it is administered quickly after ingestion of the toxin — in a supervised medical setting. This property is not yet recognized by European regulations as a public health claim, but the data from this review are among the most solid available on this subject.
Gastroenteritis is not an acute poisoning to neutralize: it's an infectious response in which the virus — norovirus or rotavirus — has already integrated into the cells of the intestinal wall. Activated charcoal has no documented mechanism of action against these pathogens, and no clinical study demonstrates that it reduces the duration or severity of a viral gastroenteritis episode.
What the evidence supports for gastroenteritis is simpler, and more effective: rehydration with oral rehydration salts, progressive reintroduction of an adapted diet, and microbiome support through targeted probiotics — three pillars developed in the previous sections of this article.
Clinical Toxicology (Phila)
Systematic review on the use of activated charcoal for gastrointestinal decontamination following acute oral overdose
This systematic review covering 296 human studies confirms that activated charcoal is studied exclusively in the context of gastrointestinal decontamination following acute drug overdose — including acetaminophen, phenobarbital, carbamazepine, and cardiac glycosides. No data from this review supports a benefit of activated charcoal in treating viral gastroenteritis symptoms.
PubMed →What science really says about digestive recovery
- Rehydration with oral rehydration solutions (ORS) remains the absolute priority for recovery: epidemiological data cited in the article report a 93% reduction in diarrhea mortality associated with their systematic use.
- The bland diet — potassium-rich bananas, white rice, applesauce, toast, and broths — is scientifically based to reduce intestinal irritation and provide the energy needed for healing.
- Probiotics with validated strains show, in several meta-analyses (BMJ Open 2021, Frontiers in Immunology 2023), encouraging results on reducing the duration of diarrheal symptoms and strengthening the intestinal barrier — data classified as orange, confirmed by peer reviews but still requiring additional studies.
- Humic acids have demonstrated stimulation of the colonic microbiota by more than 30% in a human study published in the World Journal of Gastroenterology (2016), although research remains preliminary at this stage.
- Activated charcoal has no validated clinical evidence for viral gastroenteritis and is not the holder of any authorized health claim for this use in Europe — its recognized medical use is limited to emergency decontamination in cases of acute oral poisoning.
At-risk populations: when gastroenteritis becomes an emergency
The previous article touched on this crucial point: some profiles tolerate gastroenteritis much less well than healthy adults. Here's what standard recommendations don't specify enough.
Infants and young children
An infant under 6 months can become dehydrated in just a few hours — their body contains proportionally much more water than an adult's, and each vomiting or liquid stool represents a much more significant relative loss. Pediatric oral rehydration solutions (ORS), formulated with a precise mixture of salts and glucose to optimize intestinal absorption, are the only validated response. No antidiarrheal is suitable for this age. Any symptom in an infant under 6 months requires immediate medical consultation, without waiting.
Elderly people
After age 65, the sensation of thirst diminishes — the body sends the alarm too late. Dehydration can silently set in, without the person feeling particularly thirsty. Yet, potassium contributes to normal muscle function — and electrolyte losses due to diarrhea and vomiting directly affect this function, potentially causing muscle weakness and confusion in seniors. Active hydration, even in the absence of thirst, is imperative.
Pregnant women and immunocompromised people
During pregnancy, even moderate dehydration can trigger premature contractions and affect nutrient supply to the fetus. Medical consultation should occur at the first symptoms, without delay. In immunocompromised people — transplant recipients, patients undergoing chemotherapy, people living with HIV — ordinary gastroenteritis can progress to a serious secondary bacterial infection. The microbiome, already weakened, offers less resistance to pathogens.
Warning signs: consult without delay
For all these profiles — and for any adult — five signs require urgent medical consultation:
- Fever above 38.5°C persisting beyond 48 hours
- Presence of blood in stools
- Complete absence of urine for more than 8 hours
- Mental confusion, extreme weakness, or significant dizziness
- Any symptom in an infant under 6 months
This article is for informational purposes. Consult a healthcare professional for personalized advice.
In addition to rehydration, herbal teas contribute to fluid intake while offering digestive comfort: a meta-analysis published in Alimentary Pharmacology & Therapeutics (Ingrosso et al., 2022) suggests that peppermint oil has antispasmodic properties on the intestine — light mint teas can thus provide digestive comfort.
A systematic review published in Complementary Therapies in Medicine (Ostovar et al., 2025) confirms that chamomile is generally safe at controlled dosages, with minor and self-limiting adverse effects — neither of these plants treats gastroenteritis, but they can pleasantly accompany recovery.
⚠️ People allergic to plants in the Asteraceae family (ragweed, chrysanthemum) should avoid chamomile, as a cross-reaction risk is documented.
Recovery after an episode of intense diarrhea is not limited to rehydration — the disrupted intestinal microbiome requires a targeted nutritional approach to regain its balance. Supporting microbiome restoration through adapted dietary strategies is an essential component of complete healing. [Position reflected in her published work and scientific communications, King's College London — theguthealthdoctor.com]~ Dr. Megan Rossi, Research Fellow in nutrition and gut health, King's College London
Preventing gastroenteritis: what the threshold of 10 viral particles implies for hygiene
- 10 to 100 norovirus particles are sufficient to trigger an infection — a threshold so low that it alone explains why 21 million French people contract gastroenteritis each year despite apparently correct hygiene (ECDC).
- Washing hands with soap and water for at least 20 seconds remains the most effective barrier: hand sanitizer alone is insufficient against norovirus.
- Contaminated surfaces must be disinfected with chlorine-based products at sufficient concentration, as norovirus resists concentrations usually present in tap water.
- Isolation should be maintained for at least 48 hours after complete disappearance of symptoms, as residual contagiousness can persist for up to two weeks according to CDC data.
- Not preparing meals for others during and after a gastroenteritis episode is imperative, as viral excretion extends well beyond the symptomatic phase.
- Cooking foods at temperatures above 60°C — especially seafood — destroys norovirus and is an essential preventive measure.
In the context of recovery from gastroenteritis, potassium plays a fundamental physiological role in restoring electrolyte balance. Health claims related to potassium are strictly regulated by European law: Regulation (EC) No. 432/2012 of the European Commission authorizes the following claims for potassium: "Potassium contributes to the maintenance of normal blood pressure", "Potassium contributes to normal muscle function" and "Potassium contributes to normal functioning of the nervous system". These claims are authorized in accordance with Article 13.1 of the regulation, and transposed into the Swiss market via the Ordinance on Information for Consumers (OIDAlim). In France, the DGCCRF ensures the proper application of these provisions in commercial communications and information content intended for consumers.
Conversely, activated charcoal does not benefit from any health claim authorized by the European Union for gastroenteritis, absorption of digestive toxins, or reduction of diarrhea. The only evaluated claim — concerning the reduction of flatulence — is subject to a regulatory freeze as part of the CJEU 2025 litigation on botanical substances, and does not constitute an active authorization. This is therefore an explicit regulatory limit: any communication associating activated charcoal with the management of gastroenteritis exceeds the framework of authorized claims within the meaning of Regulation (EC) No. 432/2012 and is likely to constitute a misleading commercial practice under French and European regulations.
Reduced-osmolarity oral rehydration solutions (ORS) are jointly recommended by WHO and UNICEF for the management of dehydration related to acute diarrhea, for all ages. This recommendation is based on decades of epidemiological data and international clinical trials. A large-scale analysis published in the International Journal of Epidemiology estimated that the global deployment of ORS has contributed to reducing child mortality from diarrhea by 93% worldwide — one of the most effective public health interventions ever documented. WHO emphasizes that reduced-osmolarity ORS allow for intestinal absorption of water and electrolytes superior to that of standard formulations, with a reduction of about 22% in the duration of diarrhea compared to classic ORS.
These institutional data anchor the first pillar of recovery presented in this article: strategic rehydration is not a simple comfort measure, but an intervention whose effectiveness is validated on a global scale. For adults and children alike, replenishing fluid and electrolyte losses — notably potassium, which contributes to maintaining normal muscle function as part of a varied and balanced diet and healthy lifestyle — constitutes the absolute priority from the first hours of acute gastroenteritis.
Epidemiological data published in Eurosurveillance — which covers the surveillance of secular trends in the incidence of acute gastroenteritis in general practice in France from 1991 to 2015 — establishes that more than 21 million cases of acute gastroenteritis occur each year in France. This considerable epidemiological burden makes gastroenteritis one of the most frequent infectious pathologies in the country, across all age groups, and justifies rigorous public information on evidence-based recovery strategies.
The European Centre for Disease Prevention and Control (ECDC) reports that it takes only 10 to 100 viral particles of norovirus to infect a human being, and that a sick person excretes several billion in their stool and vomit. This exceptionally low infectious dose explains the lightning-fast spread of norovirus in collective environments — homes, daycare centers, nursing homes, cruise ships — and underscores why rigorous hygiene measures constitute the first line of defense, well before any resort to supplements or comfort remedies.
Gastroenteritis is most often benign and heals spontaneously within 48 to 72 hours with appropriate home management. However, certain warning signs require immediate medical consultation — particularly in vulnerable populations. Severe dehydration can be fatal in infants and the elderly — do not wait if these signs appear.
Call emergency services or go to the emergency room without delay if you observe any of the following signs:
- Fever above 38.5°C persisting beyond 48 hours, despite appropriate symptomatic management.
- Presence of blood in stools or vomit — this sign may indicate infectious colitis or a serious digestive complication.
- Complete absence of urine for more than 8 hours — a sign of severe dehydration requiring urgent intravenous rehydration.
- Mental confusion, abnormal drowsiness, or extreme weakness — possibly indicating severe electrolyte imbalance (hyponatremia, hypokalemia).
- Intractable vomiting preventing any oral rehydration, even in repeated small quantities.
- Any gastroenteritis symptom occurring in an infant under 6 months — fluid reserves are insufficient to tolerate even moderate dehydration.
The following populations should never manage gastroenteritis without prior medical advice, even in the absence of the above warning signs: infants under 6 months, children under 2 years, people over 65 years, pregnant women, and immunocompromised people (immunosuppressive treatment, HIV, chemotherapy). In these groups, clinical deterioration can be rapid and unpredictable. Oral rehydration solutions remain the first-line measure recommended by WHO while awaiting medical evaluation, but they do not substitute for professional care in these high-risk patients.
If in doubt, always consult your doctor or pharmacist. For potentially urgent situations, call emergency services without delay.
At-risk population: Infants under 6 months, children under 2 years, people over 65 years, pregnant women, immunocompromised people
References
- Goodman C et al. "Probiotics for the prevention of antibiotic-associated diarrhoea." BMJ Open, 2021. PMID: 34385227
- Zheng Y et al. "Probiotics fortify intestinal barrier function in gastroenteritis." Frontiers in Immunology, 2023. PMID: 37168869
- Hoegberg LCG et al. "Systematic review of activated charcoal for acute poisoning." Clinical Toxicology (Phila), 2021. PMID: 34424785
- Schink M et al. "Effects of humic acids on colonic microbiota." World Journal of Gastroenterology, 2016. PMC: PMC5296205
- Ingrosso MR et al. "Efficacy of probiotics in the treatment of acute diarrhea." Alimentary Pharmacology & Therapeutics, 2022. PMID: 35942669
- Khanna R et al. "Peppermint oil and irritable bowel syndrome." Journal of Clinical Gastroenterology, 2014. PMID: 24100754
- Ostovar M et al. "Chamomile and gastrointestinal outcomes." Complementary Therapies in Medicine, 2025. PMID: 40374153
- Eurosurveillance — "Secular trends in incidence of acute gastroenteritis in general practice, France 1991–2015." PMC: PMC5743098
- ECDC — "Disease information about norovirus infection." ecdc.europa.eu
- WHO / UNICEF — Recommendations on oral rehydration solutions (ORS). World Health Organization, Geneva.
- Child Health Task Force / International Journal of Epidemiology — "Effect of oral rehydration therapy on diarrhoea mortality."
- Harvard Health Publishing — "Gastroenteritis in Adults." Harvard Medical School.
- Government of Quebec — "Eating during gastroenteritis." Quebec Health.
- European Commission — Regulation (EU) No. 432/2012 establishing the list of permitted health claims made on foods. EUR-Lex