The symptoms of lactose intolerance can occur after you’ve eaten or drunk something that contains lactose. Symptoms of lactose intolerance may include:
- feeling bloated
- pain or cramps in your tummy (abdomen)
- feeling sick
These symptoms may be caused by problems other than lactose intolerance. If you have any of these symptoms for more than a few days see your GP for advice.
Your GP will ask about your symptoms and examine you. He or she may ask you to keep a diary of your symptoms and what you eat and drink on a day-to-day basis. This will help your GP to look for any links between your symptoms and your diet.
Your GP may suggest you completely remove foods and drinks containing lactose from your diet for a trial period of two weeks. If your symptoms get better during this time, but come back when you start having lactose again, it's likely that you have lactose intolerance.
If you think your child may have symptoms of lactose intolerance, your GP may ask for a sample of his or her faeces (stool sample). This will be sent away for testing to check if your child’s body is absorbing lactose.
Having specific tests to diagnose if you have lactose intolerance is uncommon. However, if there is uncertainty about your diagnosis, your GP may refer you to have one or more of the following tests.
- Hydrogen breathe test. After you’ve drunk some milk, the level of hydrogen (a type of gas) in your breath will be measured. Lactose intolerance can cause the bacteria in your bowel to produce more hydrogen than normal. Therefore, if there’s a large amount of hydrogen in your breath, this may be a sign that you have lactose intolerance.
- A lactose tolerance blood test. Your doctor will take a blood sample after you’ve had some lactose by mouth to measure your blood sugar (glucose) level. If your blood sugar level increases by a small amount or not at all, this suggests that your body hasn’t digested or absorbed the lactose. This is a sign that you may have lactose intolerance.
- Biopsy. If your diagnosis is uncertain you may need to have a biopsy (a small sample of tissue) taken from the lining of your small bowel. This is done using a narrow, flexible, tube-like instrument called an endoscope. The sample will be sent to a laboratory to be tested for lactase.
There isn’t a cure for lactose intolerance, but you can control your symptoms. Milk and dairy products are the main sources of lactose and cutting down how much of these products you have may help your symptoms. We’ve put together some tips to help you with this.
- Hard cheeses, such as Cheddar, Edam and Parmesan, only contain a small amount of lactose. Therefore, you may be able to eat these without having any symptoms.
- You may also find that you can eat yoghurt without any problems. This is thought to be partly because of the effects of the bacteria that are used to produce yoghurt.
- You can also buy lactase preparations to take if you eat foods containing lactose.
- There may be lactose in some foods that you don’t expect to contain it, for example bread, cakes, cereals, margarine and some ready meals. Check the ingredients as the label should say whether a product contains lactose.
- You may be able to have some milk (about 200ml – a small glass) without reacting to it. You could try having small amounts of milk to find out how much you can drink without getting any symptoms.
- You can buy milk and other products that contain a reduced amount of lactose. It’s important to remember that milk from goats and sheep contains lactose and so these aren’t suitable alternatives to cow’s milk.
- Some medicines may contain lactose. Always ask your GP for advice and read the patient information leaflet that comes with your medicine.
If you can’t eat any dairy foods, you may not be getting enough calcium in your diet. Non-dairy foods that contain calcium include green leafy vegetables, soya beans, tofu and nuts. Talk to your GP about your diet if you have any questions. He or she may refer you to a dietitian for help and support. Your GP may also recommend that you take calcium and vitamin D supplements.
Lactase deficiency is when your body doesn’t produce enough lactase, which can lead to symptoms of lactose intolerance.
There are three main types of lactase deficiency.
- Primary lactase deficiency is caused by an inherited faulty gene that runs in families. It can occur at different ages.
- Secondary lactase deficiency is when the lining of your bowel becomes damaged by a separate condition such as gastroenteritis. This may reduce the amount of lactase that your body makes. Secondary lactase deficiency is usually temporary and gets better once you have recovered from the condition that caused it.
- Congenital lactase deficiency is a condition that also runs in families, but it’s very rare. It can cause you to produce little or no lactase from birth, and if left untreated, it can lead to serious complications. To find out more about congenital lactase deficiency see our FAQ.
If you have lactose intolerance, you can control your symptoms by reducing the amount of lactose in your diet. However, the lack of dairy products in your diet will mean you need to get vitamin D and the mineral calcium, from other sources. If you don’t get enough calcium in your diet, your bones may become weak and you may develop a condition known as osteopenia.
Babies born with the rare but more severe form of lactose intolerance may not grow as they should if they don’t receive the right nutrients. They will need to be fed a lactose-free formula from birth.
Is lactose intolerance the same as a milk allergy?
No. If you have lactose intolerance, it means your body can’t break down a sugar in milk called lactose. If you have a milk allergy, it means you're allergic to some of the proteins found in milk.
Lactose intolerance and milk allergy can be confused because the symptoms of both occur after eating or drinking dairy products.
If you have lactose intolerance, it means your body doesn’t have enough lactase. This is an enzyme (a type of chemical) that your body needs to break down the lactose in milk. If lactose isn’t broken down, it can cause symptoms, such as diarrhoea and bloating.
If you have an allergy to milk, your body mistakes some of the proteins found in milk as harmful, leading to an allergic reaction.
The symptoms of milk allergy are often mild and may be similar to those of lactose intolerance. For example, you may get pain in your tummy (abdomen) and diarrhoea. However, some allergic reactions can be severe (anaphylaxis) and your symptoms might include:
- a swollen tongue or throat
- sudden wheezing, tightness in your chest or difficulty breathing
- a hoarse voice
Lactose intolerance tends to affect older children and adults, whereas milk allergy is much more common in babies and young children. It's important to determine which one you have, because of the risk of a severe allergic reaction.
If you or your child feels unwell after drinking milk or eating dairy products, see your GP. Don't cut milk or dairy products out of your or your child's diet without talking to your GP first. Babies with a cow’s milk allergy may be given a special formula. It’s important to remember that milk from goats and sheep contains lactose and so these aren’t suitable alternatives to cow’s milk.
Can babies be born with lactose intolerance?
It's possible, but it's very rare for babies to be born with lactose intolerance.
Some babies may be born without any lactase in their bodies, but it’s very rare. The condition is known as congenital lactase deficiency.
If your baby has congenital lactase deficiency, he or she may develop diarrhoea when they drink milk (breast milk or formula milk) that contains lactose.
The only treatment for congenital lactase deficiency is to remove lactose from your baby’s diet from birth. Your GP will refer you to a specialist to confirm the diagnosis and arrange for you and your baby to see a dietitian. A dietitian can help ensure your baby’s diet is lactose-free. Your baby will probably need to take calcium and vitamin D supplements.
Lactose overload can sometimes be mistaken for lactose intolerance in babies. This can occur if your baby drinks a large amount of milk that he or she can’t digest. Lactose overload can cause pain in your baby’s tummy (abdomen) and very frequent bowel movements.
If your baby seems to be having problems with feeding or is having symptoms such as diarrhoea, see your GP. Don't stop breastfeeding or giving your baby milk without seeing your GP first.
Can I drink soya milk if I have lactose intolerance?
Yes, as soya milk doesn't contain lactose.
Although there isn’t a cure for lactose intolerance, you can control your symptoms by reducing the amount of lactose in your diet. One way of doing this is by drinking soya milk instead of cow, sheep or goat milk, as it doesn't contain any lactose.
It's important not to completely cut out dairy products from your diet unless you're very sensitive to lactose. This is because these foods are an important source of calcium and vitamin D. Calcium is important to keep your bones healthy. If you want to drink soya milk as an alternative, it's a good idea to choose a product that has added calcium.
If you need more information, ask your GP for advice.
- Lactose intolerance. PatientPlus. www.patient.co.uk/patientplus.asp, published 10 December 2013
- Food allergy and food intolerance. PatientPlus. www.patient.co.uk/patientplus.asp, published 20 April 2011
- Pediatric lactose intolerance. Medscape. www.emedicine.medscape.com, published 20 December 2013
- Lactose intolerance. Medscape. www.emedicine.medscape.com, published 15 March 2013
- Lactose intolerance. Food Standards Agency. www.eatwellscotland.org, accessed 19 May 2014
- Lactose intolerance. British Nutrition Foundation. www.nutrition.org.uk, published September 2009
- Bone and joint health – diet and bone health. British Nutrition Foundation. www.nutrition.org.uk, published July 2009
- Eadala P, Waud J, Matthews S, et al. Quantifying the hidden lactose in drugs used for the treatment of gastrointestinal conditions. Aliment Pharmacol Ther 2009; 29(6):677–87. doi: 10.1111/j.1365-2036.2008.03889.x
- Milk allergy and intolerance, Reduced lactose or lactose free. Food Standards Agency. www.eatwellscotland.org, accessed 19 May 2014
- Milk Allergy. Allergy UK. www.allergyuk.org, published December 2013
- Anaphylaxis and severe allergic reactions. Allergy UK. www.allergyuk.org, published March 2012
- Lactose intolerance. CORE. www.corecharity.org.uk, published November 2005
- Martin, EA. Concise colour medical dictionary. 3rd ed. Oxford: Oxford University Press 2002: 232
- Lactase deficiency. BMJ Best Practice. www.bestpractice.bmj.com, published 15 January 2014
- Lactose overload in babies. Australian Breastfeeding Association. www.breastfeeding.asn.au, published October 2012
We’d love to know what you think about what you’ve just been reading and looking at – we’ll use it to improve our information. If you’d like to give us some feedback, our short form below will take just a few minutes to complete. And if there's a question you want to ask that hasn't been answered here, please submit it to us. Although we can't respond to specific questions directly, we’ll aim to include the answer to it when we next review this topic.
Let us know what you think using our short feedback form Ask us a question
Reviewed by Kuljeet Battoo, Bupa Health Information Team, July 2014.
Let us know what you think using our short feedback form Ask us a question
About our health information
At Bupa we produce a wealth of free health information for you and your family. We believe that trustworthy information is essential in helping you make better decisions about your health and care. Here are just a few of the ways in which our core editorial principles have been recognised.
Information StandardWe are certified by the Information Standard. This quality mark identifies reliable, trustworthy producers and sources of health information.
HONcodeThis site complies with the HONcode standard for trustworthy health information.
What our readers say about us
But don't just take our word for it; here's some feedback from our readers.
“Simple and easy to use website - not alarming, just helpful.”
“It’s informative but not too detailed. I like that it’s factual and realistic about the conditions and the procedures involved. It’s also easy to navigate to areas that you specifically want without having to read all the information.”
“Good information, easy to find, trustworthy.”
Our core principles
All our health content is produced in line with our core editorial principles – readable, reliable, relevant – which are represented by our diagram.
In a nutshell, our information is jargon-free, concise and accessible. We know our audience and we meet their health information needs, helping them to take the next step in their health and wellbeing journey.
We use the best quality and most up-to-date evidence to produce our information. Our process is transparent and validated by experts – both our users and medical specialists.
We know that our users want the right information at the right time, in the way that suits them. So we review our content at least every three years to keep it fresh. And we’re embracing new technology and social media so they can get it whenever and wherever they choose.
Here are just a few of the ways in which the quality of our information has been recognised.
The Information Standard certification scheme
You will see the Information Standard quality mark on our content. This is a certification programme, supported by NHS England, that was developed to ensure that public-facing health and care information is created to a set of best practice principles.
It uses only recognised evidence sources and presents the information in a clear and balanced way. The Information Standard quality mark is a quick and easy way for you to identify reliable and trustworthy producers and sources of information.
Certified by the Information Standard as a quality provider of health and social care information. Bupa shall hold responsibility for the accuracy of the information they publish and neither the Scheme Operator nor the Scheme Owner shall have any responsibility whatsoever for costs, losses or direct or indirect damages or costs arising from inaccuracy of information or omissions in information published on the website on behalf of Bupa.
Plain English Campaign
Our website is approved by the Plain English Campaign and carries their Crystal Mark for clear information. In 2010, we won the award for best website.
Website approved by Plain English Campaign.
British Medical Association (BMA) patient information awards
We have received a number of BMA awards for different assets over the years. Most recently, in 2013, we received a 'commended' award for our online shared decision making hub.
If you have any feedback on our health information, we would love to hear from you. Please contact us via email: email@example.com. Or you can write to us:
Health Content Team
15-19 Bloomsbury Way