How Lactose Intolerance Can Surprisingly Cause Constipation

Lactose intolerance can sometimes lead to constipation, affecting around 30% of those with the condition. Symptoms usually appear within one to two hours after eating or drinking lactose-containing products. Understanding the link between the two can help manage discomfort effectively. Lactose intolerance occurs when the body struggles to digest lactose, a sugar found in milk and dairy. For some, this results in constipation—defined as infrequent or difficult bowel movements, typically fewer than three times a week. While many associate lactose intolerance with diarrhoea, constipation is also a recognised symptom.

Most people with the condition can tolerate up to 12 grams of lactose without problems. Reducing or cutting out lactose from the diet often eases symptoms, including constipation. Over-the-counter lactase enzyme supplements, such as Lactaid, can also prevent or relieve discomfort by aiding digestion.

If constipation lasts longer than a week, medical advice is recommended, as it could signal another issue like irritable bowel syndrome (IBS). Similarly, if at-home treatments show no improvement after a week, consulting a doctor may be necessary. Immediate medical attention should be sought if constipation is accompanied by rectal bleeding, blood in the stool, or severe abdominal pain. Managing lactose intolerance involves monitoring dietary intake and using supplements when needed. While constipation is less commonly discussed, it remains a significant symptom for many. Recognising when to seek medical help ensures better long-term digestive health.