---
title: "Lactose intolerance: Symptoms & Treatment | HealthAnswers"
description: "Lactose intolerance — difficulty digesting milk sugar, symptoms after dairy, diagnosis, and managing diet without missing calcium."
url: https://healthanswers.co.uk/conditions/lactose-intolerance/
robots: noindex
---

# Lactose intolerance: Symptoms & Treatment | HealthAnswers

Health A–Z

Lactose intolerance — difficulty digesting milk sugar, symptoms after dairy, diagnosis, and managing diet without missing calcium.

Written by HealthAnswers editorial team Medically reviewed by [HealthAnswers UK doctor review panel](https://healthanswers.co.uk/our-doctors/) Reviewed 3 July 2026

## Quick answer

What is lactose intolerance? Lactose intolerance means insufficient lactase enzyme to break down lactose (milk sugar) — causing bloating, wind, cramps, and diarrhoea after dairy products. Different from milk allergy (immune reaction). Common in adults especially of East Asian, African, and South Asian background. Managed by reducing lactose, using lactose-free milk, or lactase enzyme tablets — not always needing complete dairy avoidance. Ensure adequate calcium from other sources if dairy limited.

## Who is this page for?

This page is for people in the UK who want a plain-English overview of Lactose intolerance, including when to seek help and what NHS care usually involves. It explains general information, not what is wrong with you personally.

## Who should skip this page?

Skip this page if you need a diagnosis, a prescription, or emergency care. It cannot replace a GP, pharmacist, NHS 111 or 999. If you are in immediate danger, call 999; for urgent advice that is not life-threatening, call 111 in England, Scotland or Wales, or use your GP out-of-hours service in Northern Ireland.

On this page 8 sections

## Key facts about lactose intolerance

- Lactose intolerance is very common globally — less common in Northern European populations with historical dairy farming.
- Symptoms start 30 minutes to 2 hours after lactose — bloating, wind, diarrhoea, cramps — not immediate like allergy.
- Milk allergy is immune-mediated — can cause rash, wheeze, anaphylaxis — more common in children.
- Hard cheeses and yoghurt often tolerated — lower lactose than fresh milk.
- Hydrogen breath test or trial elimination confirms diagnosis — not usually needing invasive tests.

## Lactose intolerance — milk sugar malabsorption

**Lactose** is **disaccharide sugar** in **milk and dairy** — requires **lactase enzyme** in **small intestine** to split into **glucose + galactose** for absorption.

**Lactase non-persistence** — **genetically programmed decline** after weaning — **normal for most humans globally** — **~65% world population**.

**Northern Europeans** — **lactase persistence mutation** — **dairy tolerance common**.

## Symptoms

**After lactose load** (dose-dependent):

- bloating , flatulence

- abdominal cramps

- borborygmi (rumbling)

- loose stool/diarrhoea

**Timing:** **30 min – 2 hours** — **intestinal fermentation** by bacteria

**NOT:**

- immediate urticaria — allergy

- weight loss , blood in stool — investigate other causes

## Lactose intolerance vs milk allergy

| | Lactose intolerance | Milk allergy |
| --- | --- | --- |
| Mechanism | Enzyme deficiency | IgE/non-IgE immune |
| Onset | Delayed | Minutes–hours |
| Anaphylaxis | No | Possible |
| Age | Teens/adults common | Infants common |

**Milk allergy** — separate condition — paediatric/allergy clinic.

## Diagnosis

- Clinical history — relationship to dairy dose

- 2–4 week low lactose trial — symptoms improve

- Lactose challenge — symptoms return

- Hydrogen breath test — specialist

- Exclude coeliac — IgA TTG — see [coeliac disease](https://healthanswers.co.uk/conditions/coeliac-disease/)

## Management

### Reduce lactose dose

- trial tolerance level — may tolerate milk in tea not pint of milk

### Lactose-free products

- Lactose-free milk — same calcium

- plant milks — check calcium fortified

### Lactase supplements

- tablets with dairy meal

### Usually tolerated

- hard cheese

- butter — minimal lactose

- probiotic yoghurt — individual trial

## Nutrition if dairy limited

**Calcium targets:**

- 700mg/day adults — 1000mg pregnancy

**Sources:**

- fortified plant milk

- tinned fish with bones

- green leafy veg

- fortified bread

- supplements if inadequate

**Vitamin D** — **see NHS guidance**

## Secondary lactose intolerance

**Temporary after:**

- gastroenteritis

- coeliac (until treated)

- IBD flare

**Lactase returns** when **gut heals** — **retrial dairy later**.

## When to see GP

**Red flags NOT lactose alone:**

- nocturnal diarrhoea

- weight loss

- rectal bleeding

- anaemia

→ **IBD**, **coeliac**, **cancer screen** as indicated.

Lactose intolerance is **annoying not dangerous** — **diagnosis prevents unnecessary dairy fear** and ** ensures calcium** if intake drops.

## ! When to see a GP about lactose intolerance

See a GP if digestive symptoms persist — exclude coeliac disease, IBS, and inflammatory bowel disease. Same-day if blood in stool, weight loss, or symptoms waking you at night — not typical lactose intolerance alone. Dietitian advice if excluding dairy long term — calcium and vitamin D planning especially children and pregnancy.

## Common questions about lactose intolerance

What are the symptoms of lactose intolerance? Bloating, excessive wind, abdominal cramps, gurgling, diarrhoea or loose stools — typically 30 minutes to 2 hours after milk, ice cream, soft cheese, or large dairy portions. Severity depends on lactose dose and your enzyme level — small amounts in tea may be fine. What is the difference between lactose intolerance and milk allergy? Lactose intolerance — digestive enzyme deficiency — not immune — never causes anaphylaxis. Milk allergy — immune reaction to milk protein — can cause urticaria, vomiting, wheeze, anaphylaxis within minutes to 2 hours — more common in infants. Different tests and treatments. Can I still eat cheese if lactose intolerant? Often yes — aged hard cheeses (cheddar, parmesan) contain minimal lactose. Yoghurt with live cultures may be tolerated — bacteria partially digest lactose. Fresh milk, ice cream, and soft cheeses highest lactose — most problematic. How is lactose intolerance diagnosed? Clinical history often sufficient — trial off lactose then challenge. Hydrogen breath test after lactose drink — rises if malabsorption. Coeliac screen if symptoms overlap — untreated coeliac causes secondary lactose intolerance improving on gluten-free diet. Do lactase enzyme tablets work? Lactase supplements (Lactaid etc.) taken with dairy help many people digest lactose — effectiveness varies. Lactose-free milk has enzyme added — tastes slightly sweeter — good calcium source.

## Sources

- [NHS — Lactose intolerance](https://www.nhs.uk/conditions/lactose-intolerance/)