16.2 GI Self-Care: Heartburn, Constipation & Diarrhoea
Key Takeaways
- Heartburn red flags requiring referral: dysphagia, odynophagia, weight loss, GI bleeding or haematemesis, anaemia, symptoms persisting beyond 2 weeks, and age >55 with new-onset dyspepsia.
- Antacids (aluminium/magnesium hydroxide) suit occasional heartburn; H2-blockers (famotidine) and PPIs (omeprazole 20 mg) are for frequent symptoms — counsel short-term OTC use limits.
- First-line constipation management is fibre, fluid, and an osmotic laxative (lactulose or macrogol); stimulants (senna, bisacodyl) are short-term rescue therapy.
- Oral rehydration salts are the priority in acute diarrhoea; loperamide is appropriate for acute non-bloody, afebrile diarrhoea but must be AVOIDED if blood or high fever suggests invasive bacterial infection.
- Diarrhoea red flags: blood/mucus in stool, severe dehydration, persistent >48 hours, and infants or frail elderly patients.
Heartburn and Dyspepsia
Heartburn is retrosternal burning from acid reflux. Lifestyle first: weight reduction, smaller meals, avoid late meals/lying down within 3 hours, limit caffeine, alcohol, spicy and fatty foods, stop smoking.
OTC options by frequency
| Frequency | Treatment | Example |
|---|---|---|
| Occasional (intermittent) | Antacid — rapid neutralisation | Aluminium/magnesium hydroxide suspension 10–20 mL after meals and at bedtime |
| Frequent (≥2×/week) | H2-blocker or PPI | Famotidine 20 mg once or twice daily; omeprazole 20 mg once daily (take 30 min before breakfast) |
Counsel PPI OTC use for a maximum of 14 days without medical advice; if symptoms recur after stopping, refer.
Heartburn red flags — REFER (do not treat OTC)
- Dysphagia (difficulty swallowing) or odynophagia (painful swallowing)
- Unintended weight loss
- GI bleeding — haematemesis (vomiting blood) or melaena (black, tarry stools)
- Anaemia on testing
- Symptoms persisting beyond 2 weeks despite OTC therapy
- Age >55 with new-onset dyspepsia (warrants endoscopy to exclude malignancy)
- Severe epigastric pain, jaundice, previous gastric surgery, family history of GI cancer
Antacid counselling: magnesium-containing products may cause diarrhoea; aluminium-containing may cause constipation; separate antacids from other drugs by 2 hours (they can reduce absorption of antibiotics, iron, levothyroxine, PPIs).
Constipation
Constipation is fewer than 3 bowel movements per week, hard stools, or straining. First-line is non-pharmacological: fibre 25–30 g/day, adequate fluid (1.5–2 L), and exercise.
Laxative classes
| Class | Examples | Use |
|---|---|---|
| Osmotic | Lactulose 15–30 mL daily, macrogol (PEG 3350) sachets | First-line; draws water into bowel; gentle, 1–2 day onset |
| Stimulant | Senna 7.5–15 mg at night, bisacodyl 5–10 mg at night | Short-term rescue; onset 8–12 h; avoid chronic use — bowel habituation, electrolyte disturbance, colonic atony |
| Bulk-forming | Ispaghula (psyllium), methylcellulose | Adjunct with fibre; must take with fluid to avoid obstruction |
| Stool softener | Docusate sodium | Mild; limited efficacy |
Refer if: persistent constipation despite laxatives >2 weeks, blood in stool, severe abdominal pain, unexplained weight loss, alternating diarrhoea/constipation, or new onset in elderly (rule out obstruction or malignancy).
Acute Diarrhoea
Most acute diarrhoea is viral and self-limiting (1–5 days). The priority is fluid and electrolyte replacement.
- Oral rehydration salts (ORS) — the cornerstone; take frequent small sips after each loose stool. Commercial sachets mixed to the stated volume (not diluted further).
- Loperamide — antimotility; useful for acute, non-bloody, afebrile diarrhoea in adults when symptomatic control is needed (e.g. travel). Initial 4 mg, then 2 mg after each loose stool, max 16 mg/day.
When NOT to give loperamide
Avoid loperamide if any feature suggests invasive bacterial infection:
- Blood or mucus in stools
- High fever
- Severe, prolonged illness
Loperamide can slow clearance of the organism and prolong toxin exposure, especially in Shigella, Salmonella, Campylobacter, E. coli O157 (risk of haemolytic uraemic syndrome).
Diarrhoea red flags — REFER
- Blood/mucus in stool
- Severe dehydration — sunken eyes, reduced skin turgor, dizziness, oliguria, drowsiness
- Persistent >48 hours in adults (sooner in children/elderly)
- Infants, frail elderly, immunocompromised, or pregnant patients
- High fever, severe abdominal pain
Worked example — heartburn selection
A 42-year-old reports heartburn 3–4 times per week after large meals, no red flags, no weight loss, no dysphagia. This is frequent heartburn (≥2×/week). Lifestyle advice first (weight, late meals, alcohol, smoking). Because symptoms are frequent, a simple antacid is inadequate — recommend an H2-blocker (famotidine 20 mg once or twice daily) or a PPI (omeprazole 20 mg once daily, 30 min before breakfast). Counsel a maximum of 14 days OTC use; if symptoms recur after stopping, or any red flag appears, refer. Separately, advise the patient that antacids taken alongside other medicines (iron, levothyroxine, antibiotics, PPIs) should be spaced by at least 2 hours to avoid reducing their absorption.
Worked example — constipation safety
A 70-year-old takes codeine for osteoarthritis and has not opened his bowels for 5 days. First-line is macrogol sachets (2–3 sachets daily in divided doses in water) plus fibre and fluid. If no response in 48 hours, add a stimulant (senna 7.5 mg at night). Stimulants are short-term rescue only; chronic codeine-related constipation needs medical review for ongoing opioid strategy. Refer urgently if abdominal pain, vomiting, distension or blood appears — possible obstruction in an elderly patient.
Worked example — traveller's diarrhoea
A 35-year-old returns from travel with watery diarrhoea for 1 day, no blood, no fever, well hydrated. Oral rehydration salts after each loose stool, plus loperamide 4 mg initially then 2 mg after each loose stool (max 16 mg/day) if he needs symptomatic control for travel. Counsel to stop loperamide and seek medical review if blood, high fever, or symptoms beyond 48 hours develop. Routine antibiotics are not an OTC pharmacy supply; refer if a suspected invasive bacterial cause or moderate-to-severe illness.
Key exam traps
- PPI onset is not immediate — several days for full effect; counsel regular daily use, not PRN.
- Loperamide is contraindicated in bloody/febrile invasive diarrhoea — it can worsen toxin-mediated disease.
- Stimulant laxatives (senna, bisacodyl) for chronic use risk bowel habituation and electrolyte disturbance.
- Antacids reduce absorption of many drugs — separate by 2 hours.
- Age >55 with new-onset dyspepsia is a referral red flag, not a PPI trial.
A 62-year-old reports new-onset heartburn for 3 weeks with unintended weight loss of 4 kg and occasional dysphagia. What is the correct pharmacist action?
A patient has acute diarrhoea after returning from travel. Stools are watery, no blood, no fever, and the patient is otherwise well. Which approach is most appropriate?
Which laxative regimen is most appropriate first-line for a generally well adult with simple dietary constipation?