References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Diarrhoea is one of the most common symptoms experienced by people living with HIV. It can be caused by HIV medication (particularly protease inhibitors), opportunistic infections, or the same gastrointestinal conditions that affect anyone. While usually manageable, persistent or severe diarrhoea needs investigation and treatment.
Here’s what causes it and how to cope.
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Common Causes
| Cause | Detail |
|---|---|
| Medication side effect | Protease inhibitors (especially lopinavir/ritonavir) are the most common culprits |
| Opportunistic infections | Cryptosporidium, microsporidium, CMV colitis, MAC (mainly low CD4) |
| Other infections | C. difficile, Salmonella, Campylobacter, norovirus |
| HIV enteropathy | HIV directly damaging the gut lining |
| Irritable bowel syndrome | Common in the general population too |
| Lactose intolerance | More common with gut inflammation |
| Anxiety and stress | Can exacerbate gut symptoms |
When to Seek Help
- Diarrhoea lasting more than 2 weeks
- Blood or mucus in stools
- Fever with diarrhoea
- Severe dehydration (dizziness, dry mouth, reduced urine)
- Significant weight loss
- Diarrhoea starting soon after new medication
Investigation
Your HIV clinic may:
- Send stool samples for bacteria, parasites and viruses
- Check CD4 count (opportunistic infections more likely if below 200)
- Review your medication for likely culprits
- Blood tests for inflammation and nutrition
- Refer for endoscopy if needed
Management
- Often settles in the first few weeks
- Loperamide (Imodium) can help symptomatically
- If persistent, switching to a different ART regimen usually resolves it
- Treat the specific infection
- Start or optimise ART — immune recovery is the best long-term protection
Self-care
- Stay hydrated — water, oral rehydration solutions, clear soups
- Eat small, frequent meals
- Avoid very spicy, greasy or high-fibre foods during episodes
- Bananas, rice, toast and boiled potatoes are usually well tolerated
- Avoid caffeine and alcohol
Read more: Side effects of treatment | Healthy eating with HIV | What is HIV?
Frequently Asked Questions
Will my medication always cause diarrhoea?
Not necessarily. Some drugs are more likely than others. If diarrhoea persists, your HIV team can switch to a better-tolerated option.
Can I take Imodium with HIV medication?
Yes, loperamide is generally safe with ART. Check with your HIV pharmacist if you’re on a boosted PI, as levels can be slightly raised.
Should I worry about diarrhoea affecting my medication absorption?
Mild diarrhoea is unlikely to affect drug levels. Severe diarrhoea within an hour of taking your dose may warrant retaking it — contact your clinic for advice.
Related reading
- A to Z of Sex: Sexual Health Terms Explained
- Alcohol and HIV: What You Need to Know
- Anxiety and HIV: Coping and Getting Support
- Are All STIs Curable?
- Blood Problems and HIV: Anaemia, Low Platelets and More
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
