Lactose intolerance is common and harmless to the bowel. It is not an allergy. Most people can still enjoy some dairy, especially yoghurt, hard cheese and, for many people, laban, and keep a good calcium intake with simple adjustments.

What is it?

Lactose is the natural sugar in milk. It is digested by an enzyme called lactase in the lining of the small bowel. Many adults make less lactase as they grow older. Undigested lactose reaches the large bowel, where bacteria ferment it, producing gas and drawing water into the bowel.

Low lactase is common worldwide, including in the Middle East, though how common it is varies between communities and families. Many people with low lactase have few or no symptoms.

Symptoms

Symptoms usually start from 30 minutes to a few hours after taking milk or milk products, and depend on how much lactose is taken:

• Bloating and wind
• Abdominal cramps or rumbling
• Loose stools or diarrhoea
• Nausea in some people

These symptoms are uncomfortable but do not damage the bowel.

Not an allergy

Cow's milk allergy is a reaction of the immune system to milk proteins. It is mainly seen in infants and young children and can cause rash, swelling, vomiting or breathing difficulty. Lactose intolerance is a digestive problem with milk sugar. It does not cause rashes or breathing problems and does not require avoiding every trace of milk.

Other causes of low lactase

• A recent bout of gastroenteritis, after which symptoms can last for weeks before settling
• Coeliac disease or Crohn's disease affecting the small bowel
• Some gut infections, such as giardia
• In these cases lactose intolerance is often temporary and improves once the cause is treated. Symptoms such as weight loss, anaemia, blood in the stool or night-time diarrhoea are not explained by lactose intolerance and need assessment

Diagnosis

Often the simplest test is a trial: avoid lactose for about two weeks, then reintroduce it and see whether symptoms return. A hydrogen breath test can confirm the diagnosis if needed. If symptoms continue despite avoiding lactose, another cause such as irritable bowel syndrome should be considered; IBS and lactose intolerance often overlap.

What to eat

• Most people can tolerate a glass of milk of about 200 to 250 mL at a time, especially with a meal, so complete avoidance is rarely needed
• Yoghurt with live cultures is often better tolerated, because its bacteria help break down lactose. Many people also tolerate laban, but it can contain almost as much lactose as milk, so start with small amounts
• Hard and aged cheeses contain very little lactose
• Lactose-free milk and laban are widely available, and lactase drops or tablets can be taken with dairy
• Camel milk and goat milk contain about as much lactose as cow's milk, so they are not lactose-free alternatives
• Keep your calcium intake up: adults generally need about 1,000 mg a day, more in older age. Good non-dairy sources include sardines and other fish eaten with bones, tahini, almonds, green vegetables such as broccoli, kale and okra (spinach is a poor source), and calcium-fortified foods and plant drinks

Common questions

This leaflet is general information and does not replace advice from your own doctor. Version 1.0, October 2026. Next review October 2028.