Diarrhoea and Dehydration in Older Adults

What is diarrhoea?

Diarrhoea means passing loose or watery stools three or more times in a day, or more often than usual for the person. Acute diarrhoea lasts less than two weeks and is usually infectious; persistent diarrhoea lasts two to four weeks; chronic lasts longer than four weeks and always needs medical investigation.

Common causes in older adults

• Infections: viral (such as rotavirus and norovirus), bacterial (food and waterborne, including *E. coli*, *Salmonella*, *Shigella*, cholera) and parasitic, particularly in the monsoon and summer, and after eating contaminated street food, unwashed fruit or unsafe water; see monsoon infections and older adults.
• Antibiotic-associated diarrhoea, including infection with *Clostridioides difficile* after antibiotics, which can be severe; see probiotics for older adults: what they can and cannot do.
• Medicines: metformin, laxatives, magnesium-containing antacids, some antibiotics, colchicine, some blood pressure and heart drugs, chemotherapy, anti-inflammatory painkillers, iron and many others.
• Constipation with overflow: liquid stool leaking around hard stool; see bowel incontinence and constipation in later life.
• Food intolerance, such as lactose intolerance, excess sweeteners, and fatty or spicy foods.
• Bowel diseases: inflammatory bowel disease, coeliac disease, microscopic colitis, bowel cancer.
• Pancreatic or bile problems.
• Faecal impaction is a very common hidden cause in frail or bedridden people.

Why dehydration is more dangerous in older adults

Older bodies hold less water, thirst is blunted, and kidneys are more easily injured by fluid loss. Medicines such as water tablets, blood pressure drugs, NSAID painkillers and metformin add risk, and confusion and falls can be the first sign; see delirium in older adults: a medical emergency families miss.

Signs of dehydration

Mild to moderate: - Thirst (may be absent), dry mouth and lips, a sticky tongue. - Dark yellow, strong-smelling urine, or passing little urine. - Tiredness, headache, dizziness on standing. - Sunken eyes, dry skin that stays "tented" when pinched (less reliable in older skin). - Constipation, muscle cramps.

Severe (needs urgent care): - Very little or no urine for eight hours or more. - Confusion, drowsiness, irritability, difficulty waking. - Fast heartbeat, fast breathing, low blood pressure, cold or clammy hands and feet, fainting. - Sunken eyes, very dry mouth. - Inability to drink or keep fluids down.

What to do at home

### 1. Rehydrate

Oral rehydration solution (ORS) is the cornerstone. It contains the right balance of salts and sugar to be absorbed by the gut, and saves lives worldwide.

• Use ORS packets from the pharmacy or government health centres, mixed exactly as the packet says, with clean, boiled and cooled or safe drinking water. Do not add extra sugar, salt or other ingredients. Discard unused ORS after 24 hours (or as the packet advises).
• Give small, frequent sips, such as a sip or a few spoons every few minutes, then larger amounts as tolerated, rather than gulping, especially if there is vomiting. As a rough guide, adults often need about 200 to 400 ml of ORS after each loose stool, but follow the packet and the doctor's advice.
• If ORS is not available at once, the World Health Organization gives a home recipe: about six level teaspoons of sugar and half a level teaspoon of salt in one litre of clean water, mixed carefully; the packet form is more reliable, and the doctor should be called. Do not use if the amounts are uncertain; too much salt is harmful.
• Other helpful fluids: thin rice water (kanji), plain buttermilk with a pinch of salt, thin dal water, clear soups, coconut water (but see potassium caution below), lightly sweetened weak tea and plain water. Avoid very sugary drinks, packaged fruit juices and fizzy drinks, which can worsen diarrhoea, and avoid alcohol and excess caffeine.
• Special conditions: in heart failure or kidney disease, fluid and salt limits apply; the doctor must guide; coconut water and some drinks contain potassium and are not suitable for advanced kidney disease; see eating with chronic kidney disease: a family guide. In diabetes, ORS contains sugar, but is still the right choice for rehydration; monitor blood sugar more often; see how to test blood sugar at home step by step.
• Monitor drinks and urine. Aim for pale urine passed every few hours.

### 2. Keep eating

Contrary to old advice, do not starve. Resume normal food as soon as the person is willing, in small, frequent portions.

• Gentle foods: rice, khichdi, curd rice, banana, boiled potato, toast, plain roti, dalia, well-cooked vegetables, soft-boiled eggs, soups, apple stewed.
• Curd and buttermilk are usually tolerated and may help.
• Avoid for a few days: very fatty or fried food, rich sweets, raw salads, strongly spiced dishes, whole milk in large amounts if lactose intolerance is suspected, and alcohol.
• Do not force large meals; offer little and often.
• Nutrition afterwards: protein and calories to recover; see how much protein do older adults need and loss of appetite in older adults: causes and practical fixes.

### 3. Medicines: be careful

• Anti-diarrhoeal drugs (loperamide and similar): should not be used if there is blood in the stool, fever, severe abdominal pain, or suspected infection like *C. difficile*, and should be used in older adults only on a doctor's or pharmacist's advice. They can cause serious side effects, constipation, bloating and, rarely, heart rhythm problems at high doses.
• Antibiotics: most diarrhoea is viral or self-limiting, and antibiotics do not help and may harm. They are used only when the doctor decides. Never use leftover antibiotics.
• Probiotics: some strains may shorten diarrhoea slightly or reduce antibiotic-associated diarrhoea, but oral rehydration is more important; see probiotics for older adults: what they can and cannot do. Avoid in seriously ill or immunocompromised people unless the doctor agrees.
• Regular medicines during diarrhoea ("sick day" guidance): certain medicines can be harmful when a person is dehydrated, notably water tablets (diuretics), ACE inhibitors and angiotensin receptor blockers, some diabetes medicines (metformin, SGLT2 inhibitors), NSAID painkillers and others. Doctors often advise temporarily pausing some of them during vomiting and diarrhoea, but this is a decision for the doctor or pharmacist, not the family; do not stop or skip on your own, particularly heart, epilepsy, Parkinson's, thyroid or insulin medicines, but call the doctor the same day and ask what to do. See polypharmacy and deprescribing.

### 4. Prevent spread and look after skin

• Hand hygiene with soap and water for everyone, after toilet use and before eating or cooking; see infection control for home caregivers.
• Clean the toilet, commode and surfaces with a disinfectant; see commode chair cleaning and hygiene.
• Wash soiled clothes and bedding hot; see disposal, laundry and odour control.
• Do not prepare food for others while ill.
• Safe water and food: boil or filter water; wash fruit and vegetables; eat freshly cooked food; avoid street food during outbreaks; refrigerate leftovers.
• Protect skin with gentle cleaning and barrier cream; see barrier creams and skin care under pads and incontinence-associated skin damage: prevention and care.
• Prevent falls to the toilet; use a commode or urinal at night; see night-time toilet trips and falls.

When to call the doctor the same day

• Diarrhoea in a frail older adult lasting more than 24 hours, or more than a few loose stools with poor drinking.
• Fever or chills.
• Vomiting with inability to keep fluids down.
• Signs of dehydration: very dry mouth, little dark urine, dizziness, new weakness.
• Blood or mucus in stool.
• Severe or increasing abdominal pain, or a swollen abdomen.
• Recent antibiotic use or hospital stay.
• Diabetes, heart, kidney or liver disease, or on insulin, diuretics, blood thinners, immune-suppressing drugs.
• Diarrhoea lasting more than a few days, or recurring.
• New confusion or drowsiness.

Call 112 or go to hospital for

• Confusion, difficulty waking, or fits.
• Fainting, severe dizziness, a very fast or weak pulse, cold clammy skin, fast breathing.
• No urine for eight hours or more, or very dark scanty urine with weakness.
• Severe abdominal pain, a hard swollen abdomen, or repeated vomiting; see fever in older adults: why it can be subtle and when to call.
• Heavy rectal bleeding or vomiting blood.
• Suspected sepsis: high fever with shaking, low blood pressure, severe weakness.

Longer-lasting diarrhoea

Diarrhoea lasting more than a couple of weeks needs tests and a medical review; do not self-treat. Prevention rests on safe food and water, hand washing, careful antibiotic use and good daily hydration.

When to ask a professional

Ask the doctor for advice early in any diarrhoea in an older adult, particularly about what to do with regular medicines. Ask a pharmacist about ORS and anti-diarrhoeal safety. Ask a dietician about recovery foods. Seek urgent help for dehydration, confusion, blood in stool, severe pain or no urine; call 112 if severe.