Symptoms of lactose intolerance

Wondering whether what you're feeling after dairy is actually lactose intolerance? Let's walk through the typical signs — what they are, when they show up, and what they can be confused with.

The common symptoms

Lactose intolerance symptoms usually affect the digestive system and typically appear from around 30 minutes to a couple of hours after eating dairy. The most common are:

• Bloating and a swollen, uncomfortable tummy
• Stomach cramps or pain
• Wind (gas)
• Rumbling or gurgling in the belly
• Loose stools or diarrhoea
• Sometimes nausea

How soon symptoms appear

Because symptoms come from lactose being fermented in the gut, they generally show up within a few hours of eating, not instantly. The timing and severity depend on how much lactose you ate and your individual threshold.

How bad it gets depends on the dose

Symptoms usually scale with the amount of lactose. A little may cause nothing; a lot causes more. This is why many people can enjoy small amounts of dairy without issue but react to a big serve.

What it can be confused with

Several other conditions cause similar gut symptoms — irritable bowel syndrome (IBS), coeliac disease, and general food-intolerance issues among them. That overlap is exactly why guessing isn't ideal, and why testing or a supervised elimination can be worth it.

When to see a doctor

See your GP if symptoms are severe or persistent, if you notice weight loss or blood in your stool, or if you're unsure of the cause — these warrant proper assessment.