Gastrointestinal Medicines

Common GI Symptoms We Treat With Medicines

People often seek treatment for:

• Heartburn and acid reflux
• Upper abdominal pain or indigestion
• Nausea and vomiting
• Constipation
• Diarrhoea
• Abdominal cramping or IBS-type symptoms
• Bloating and excess wind

Symptoms that persist, recur frequently, or are associated with weight loss, bleeding, or swallowing problems should be assessed rather than repeatedly self-treated.

Acid Reflux and Indigestion Medicines

Antacids and alginates

These provide short-term relief by neutralising stomach acid or forming a protective barrier.

Common examples include:

• alginate-based reflux suppressants
• antacid mixtures

These can be helpful for intermittent symptoms.

H2 blockers

These reduce acid production and may be used for milder reflux or short-term control.

Common examples include famotidine.

Proton Pump Inhibitors (PPIs)

PPIs reduce stomach acid production more strongly and are commonly used for reflux symptoms, gastritis, and ulcer disease.

Common examples include:

• omeprazole
• lansoprazole
• esomeprazole
• pantoprazole

Important considerations

PPIs are often used as a time-limited course to settle symptoms, then reviewed. Long-term use is sometimes appropriate but should be monitored and reviewed periodically.

Persistent symptoms despite treatment should be assessed.

Learn more:

• Reflux and heartburn
• Gastroscopy

Constipation Medicines

Constipation is common and may be linked to:

• Low fibre intake
• Dehydration
• Reduced activity
• Medication side effects
• Pregnancy
• Neurological conditions
• Irritable bowel syndrome
• Pelvic floor dysfunction

Treatment usually combines lifestyle measures with medication where appropriate. The choice of laxative depends on stool consistency, bowel pattern, and underlying cause.

Bulk-forming laxatives

These increase stool bulk by absorbing water, helping the bowel move more regularly.

Common examples include:

• Ispaghula husk
• Methylcellulose
• Sterculia

They are often used when dietary fibre is low and may be suitable for longer-term use.

Adequate fluid intake is important when using bulk-forming laxatives.

They may not be appropriate if severe constipation with hard impacted stool is present.

Osmotic laxatives

Osmotic laxatives draw water into the bowel to soften stool.

Common examples include:

• Lactulose
• Macrogol preparations

These are often used when stools are hard or difficult to pass.

Macrogols are commonly used in both routine constipation and faecal impaction under supervision.

Some people experience bloating or cramping initially.

Stimulant laxatives

Stimulant laxatives increase bowel muscle activity.

Common examples include:

• Senna
• Bisacodyl

They may be helpful when bowel movement is slow or infrequent.

Long-term unsupervised use is not generally recommended without review, as underlying causes should be considered.

Constipation Caused by Medicines

Constipation is commonly caused by:

• Opioid pain medicines
• Iron supplements
• Some antidepressants
• Anticholinergic medicines
• Calcium supplements

If constipation begins after starting a new medicine, review may be appropriate rather than simply escalating laxatives.

When Constipation Needs Assessment

Medical assessment is important if constipation is:

• New and persistent
• Associated with weight loss
• Associated with rectal bleeding
• Associated with severe abdominal pain
• Associated with vomiting
• Accompanied by a change in bowel habit that persists

Ongoing reliance on laxatives without improvement should also be reviewed.

Learn more: Constipation

Diarrhoea Medicines

Diarrhoea is commonly caused by:

• Viral gastroenteritis
• Food-related illness
• Antibiotic-associated gut disruption
• Irritable bowel syndrome
• Stress
• Inflammatory bowel disease
• Medication side effects

Most short-lived diarrhoea episodes are self-limiting and settle within a few days. The primary risk is dehydration rather than the frequency of stools alone..

Oral Rehydration Solutions

Maintaining hydration is the most important first step.

Oral rehydration solutions help replace:

• Fluids
• Salts
• Electrolytes

They are particularly important in:

• Older adults
• Children
• People with chronic illness
• Those experiencing vomiting alongside diarrhoea

Plain water alone may not replace lost electrolytes in more significant diarrhoea.

Anti-Diarrhoeal Medicines

Loperamide

Loperamide slows bowel movement and reduces stool frequency.

It may be useful for short-term control of symptoms, particularly where diarrhoea is disruptive, such as during travel or work commitments.

However, it is generally avoided if there is:

• Fever
• Blood in stool
• Severe abdominal pain
• Suspicion of bacterial infection

Symptom suppression should not delay assessment if red flags are present.

Probiotics

Some people choose to use probiotics following antibiotic-associated diarrhoea. Evidence varies, and they are not a substitute for assessment in persistent cases.

Diarrhoea Caused by Medicines

Diarrhoea is commonly triggered by:

• Antibiotics
• Metformin
• Certain antidepressants
• Magnesium-containing antacids
• Laxatives

If diarrhoea begins soon after starting a medicine, review may be appropriate before continuing long term.

When Diarrhoea Requires Urgent Assessment

Seek urgent medical advice if diarrhoea is associated with:

• Blood or mucus in stool
• High fever
• Severe abdominal pain
• Signs of dehydration
• Persistent vomiting
• Diarrhoea lasting more than several days without improvement
• Recent travel to high-risk areas

New, persistent diarrhoea in older adults should also be assessed.

Learn more: Diarrhoea and loose stools

IBS and Abdominal Cramping Medicines

IBS symptoms may include cramping pain, bloating, constipation, diarrhoea, or a mixed pattern.

Medicines used depend on the symptom pattern.

Antispasmodics

May help cramping and spasms.

Common examples include:

• mebeverine
• hyoscine butylbromide

IBS management often involves dietary and lifestyle approaches alongside medication.

Learn more: Irritable bowel syndrome