Food and water borne illness is common in India, particularly during the monsoon and hot months. Most episodes are self limiting and resolve within a few days with fluids alone.
A minority are not, and knowing the difference prevents both unnecessary antibiotics and dangerous delay.
Common Causes and Their Timing
The interval between eating and becoming ill is a useful clue to the cause.
- 1 to 6 hours: preformed toxins from staphylococcus or bacillus cereus, typically from food left out. Sudden vomiting, settles within a day
- 8 to 16 hours: clostridium species, causing cramps and diarrhoea
- 12 to 72 hours: salmonella, E coli, campylobacter, norovirus
- Days to weeks: typhoid, amoebiasis, giardia
Vomiting within a few hours of a meal usually means a toxin and settles quickly. Diarrhoea starting a day or two later suggests an organism that is still multiplying, and may last longer.
When It Is More Than Food Poisoning
Certain features point to something requiring specific treatment rather than supportive care.
- Blood or mucus in the stool: suggests dysentery, from shigella, invasive E coli or amoebiasis
- High fever lasting more than three days: raises the possibility of typhoid
- Prolonged diarrhoea beyond two weeks: suggests giardia or a parasitic cause
- Severe abdominal pain out of proportion to the illness
- Signs of dehydration that are not correcting with oral fluids
Typhoid deserves attention in our region. It presents with fever rising in a stepwise pattern over days, headache, abdominal discomfort and often constipation rather than diarrhoea early on, which is why it is missed. It needs blood culture and specific antibiotic treatment.
Assessing Dehydration in Adults
Dehydration is the main danger, and it can be judged reliably at home.
Mild: thirst, dry mouth, slightly reduced urine, urine darker than usual. Manageable at home.
Moderate: marked thirst, minimal urine over eight hours, dizziness on standing, dry skin, fatigue. Needs medical review.
Severe: confusion, not passing urine, rapid weak pulse, very low blood pressure, cold extremities, fainting. A medical emergency requiring intravenous fluids.
Urine output and colour are the most reliable indicators available at home. Passing pale urine regularly means you are keeping up.
What to Drink and Eat
Fluid replacement is the treatment. What you drink matters.
- ORS is the best option, in the correct concentration of one sachet per litre
- Coconut water, rice water and thin buttermilk are reasonable alternatives
- Avoid soft drinks and packaged fruit juice, which are too high in sugar and worsen diarrhoea
- Avoid alcohol and excess caffeine
- Eat as soon as you can tolerate it, since starving prolongs recovery
- Start with simple foods: rice, curd, banana, khichdi, toast, boiled potato
Curd is helpful rather than harmful, contrary to common advice. Avoiding all food for days is a persistent piece of bad advice that delays recovery.
Why Antibiotics Are Usually Wrong
Most food poisoning is viral or toxin mediated, and antibiotics do nothing for either. Even for many bacterial causes, antibiotics shorten the illness only marginally.
They also cause harm. They disturb gut bacteria, prolong the carrier state for salmonella, and in the case of certain E coli strains can increase the risk of a serious kidney complication.
Antibiotics are appropriate for dysentery with blood and fever, confirmed typhoid, giardia or amoebiasis, severe illness with systemic features, and in immunocompromised patients. That determination requires a doctor, often with a stool test.
Anti motility drugs such as loperamide can help adult travellers with non bloody diarrhoea, but should be avoided if there is blood or high fever.
Prevention in Indian Conditions
Practical measures reduce risk considerably without avoiding street food entirely.
- Prefer food that is freshly cooked and served hot rather than sitting out
- Choose busy stalls with high turnover over quiet ones
- Avoid pre cut fruit and salads washed in unknown water
- Drink sealed bottled water, or boiled and filtered water
- Avoid ice from unknown sources
- Peel fruit yourself
- Be cautious with chutneys and sauces left out at room temperature
- Wash hands with soap before eating, or use sanitiser
At home, avoid keeping cooked food at room temperature for more than two hours, reheat thoroughly rather than warming, store raw and cooked food separately, and use separate boards for raw meat.
Groups at Higher Risk
Some people need lower thresholds for seeking care.
- Infants and young children, who dehydrate rapidly
- Older adults, with less physiological reserve
- Pregnant women, since some infections including listeria affect the pregnancy
- People with diabetes, where dehydration and glucose control interact badly
- People on immunosuppressive treatment
- People with chronic kidney or liver disease
- People on diuretics or ACE inhibitors, which may need temporary suspension during dehydration
That last point is worth knowing. Continuing certain blood pressure and diabetes medications during significant dehydration can precipitate kidney injury, and doctors often advise pausing them briefly.
When to Seek Medical Care
See a doctor for any of these.
- Blood in stool or vomit
- Fever above 38.5 degrees or lasting beyond three days
- Inability to keep any fluid down for twelve hours
- Signs of moderate or severe dehydration
- Diarrhoea lasting more than a week
- Severe abdominal pain
- Recent antibiotic use, which raises the possibility of clostridioides difficile
- Symptoms in a high risk group
Persistent diarrhoea after a course of antibiotics is a specific pattern worth mentioning, since it needs different treatment.
Most food poisoning needs fluids, food when you can manage it and patience. Blood in the stool, fever beyond three days, or an inability to keep fluids down are the features that need medical attention rather than another day of waiting.
Our general medicine and gastroenterology departments at T. Nagar assess persistent or severe gastrointestinal infection.
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