Why Am I Suddenly Lactose Intolerant? Causes, Symptoms & What to Do

Understanding Lactose Intolerance

What Happens in the Body When You Can’t Digest Lactose?

Undigested lactose travels through the intestines to the colon, where the naturally present bacteria ferment it, causing bloating, gas, and stomach discomfort. 

You may have low levels of the enzyme lactase, which breaks down lactose, causing some lactose to travel through your gut undigested. The leftover lactose ferments, causing a release of gas that may lead to inflammation or other stomach problems.

Reducing the amount of lactose you consume can decrease the severity of lactose intolerance symptoms and side effects. LifeSpring Home Nutrition offers dairy-free meals and foods low in lactose to help you manage your condition.

How Is Lactose Intolerance Different From a Milk Allergy?

A milk allergy triggers an immune response, while lactose intolerance affects the digestive process. 

The two conditions have different causes; however, they may share overlapping symptoms and side effects, making it essential to get a medical diagnosis.

Milk allergies can develop over time, and their symptoms may resemble those of lactose intolerance. However, a milk allergy and lactose intolerance have very different causes and potential outcomes.

Allergies trigger an immune system response that can lead to inflammation, hives, anaphylaxis, or cardiovascular issues. Lactose intolerance is caused by a lack of lactase and can lead to discomfort, pain, or intestinal inflammation.

Causes of Sudden Lactose Intolerance

Why Do People Suddenly Develop Lactose Intolerance?

Medical issues can cause secondary lactose intolerance, which may develop abruptly, including infections, diseases, injuries, and some types of cancer treatment. 

The causes of lactose intolerance may include temporary conditions or medications that trigger a sudden onset of secondary lactose intolerance.

Studies have shown that “[i]njury to the intestinal mucosa can lead to secondary lactase deficiency, and resolution of the underlying cause may resolve the lactose intolerance. Common causes include:

• Gastrointestinal infections, such as those caused by rotavirus in children and Giardia lamblia
• Celiac disease
• Crohn disease
• Chemotherapy
• Antibiotics
• Small intestinal surgery
• Radiation therapy to the small intestine”

Once the underlying issues are resolved, the lactose intolerance often disappears.

What’s the Difference Between Primary and Secondary Lactose Intolerance?

Primary lactose intolerance is a genetic condition, whereas secondary lactose intolerance is a temporary condition generally caused by damage to the tissue in the small intestine. 

People with genetic factors that contribute to lifelong lactose intolerance have primary lactose intolerance. On the other hand, people who develop problems digesting lactose due to surgery, injury, illness, or medication often experience secondary lactose intolerance, which typically resolves when the underlying issue is addressed.

You benefit from consuming fewer milk products for both types of lactose intolerance.

Can Conditions Like Celiac Disease, Crohn’s Disease, or IBS Cause Lactose Intolerance?

Yes. Many medical conditions can cause secondary lactose intolerance. 

Chronic health issues, including Crohn’s disease, irritable bowel syndrome (IBS), and celiac disease, can cause secondary lactose intolerance. If you have one of these conditions and believe that you may have developed lactose intolerance, speak with your doctor to receive an accurate diagnosis and make healthy dietary changes.

LifeSpring Home Nutrition offers a variety of gluten-friendly meals and other options to support individuals with chronic health conditions.

Can Cancer Treatments or Infections Lead to Lactose Intolerance?

Yes, some forms of cancer treatment may cause you to develop temporary lactose intolerance. 

Chemotherapy that affects the intestinal lining can cause temporary lactose intolerance that will resolve once you complete treatment.

According to Nutrients, “Chemotherapy-induced mucosal injury of the small intestine may interfere with the enzymes and transporters responsible for the hydrolysis and absorption of dietary carbohydrates, causing diarrhoea, abdominal discomfort and pain.” The chemotherapy damages cells that release lactase, and they heal over time after you recover.

Does Age or Genetics Play a Role in Lactose Intolerance?

Yes. Genetics causes primary lactose intolerance, and as people age, they naturally produce less lactase, which can lead to an increase in lactose intolerance. 

A family history of lactose intolerance increases your risk of developing the condition at some point during your life.

Genetics often influences how lactase functions and your body’s ability to digest lactose. As you age, your body naturally becomes less able to produce lactase, and if you have genes that impact your digestive system, you may notice worsening symptoms over time.

Symptoms of Lactose Intolerance

What Are the Most Common Symptoms of Lactose Intolerance?

All types of lactose intolerance can cause bloating, stomach pain or discomfort, diarrhea, nausea, and excessive gas.

Some other symptoms include: 

• Unusual tiredness
• Difficulty concentrating 
• Digestive issues like stomach cramps
• Difficulty sleeping

Everyone responds differently to lactose intolerance, and the symptoms exist along a spectrum, making it challenging sometimes to identify. Confirming lactose intolerance with clinical testing ensures you understand the cause of the symptoms you experience.

Are There Non-Digestive Symptoms to Look Out For?

Yes. Some people may experience joint pain, headaches, unexplained fatigue, and a general sense of being unwell. 

Nutrient deficiencies may cause additional symptoms and side effects.

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), “Lactose intolerance may affect your health if it keeps you from getting enough nutrients, such as calcium and vitamin D.”

Adjusting your diet to compensate for the loss of vitamin D and calcium you would have gotten from dairy products can help you avoid these potential deficiencies.

When Should You See a Healthcare Provider?

Consult with a healthcare professional as soon as you notice any warning signs of a potential health issue. 

Whenever you feel that something is not right with your health, consult a healthcare provider. You know your body best, and you may notice something is off before symptoms begin. Early intervention often reduces the lasting side effects of conditions like primary or secondary lactose intolerance.

Diagnosing Lactose Intolerance

How Does a Hydrogen Breath Test (HBT) Work?

Undigested lactose becomes fermented, adding hydrogen to your breath. The test checks for an excess of hydrogen after an overnight fast.

If your doctor determines that you need a breath test, you will be required to fast the night before the test. Hydrogen from fermented lactose enters the lungs and can be measured in your exhalations.

According to the Journal of Neurogastroenterology and Motility, “In these tests, hydrogen exhaled in the breath is estimated using a gas chromatograph.” In addition, “HBTs are easy to perform and are non-invasive.”

What Is a Lactose Tolerance Test?

Generally, a lactose tolerance test involves consuming a specific amount of milk and then having blood tested at regular intervals to determine if undigested lactose causes an increase in blood glucose. 

Blood testing provides doctors with an indication of whether to conduct a breath test and other diagnostic tests. An increase in glucose may indicate digestive issues, such as lactose intolerance. Your doctor will do additional assessments and testing to ensure an accurate diagnosis.

How Is Lactose Intolerance Diagnosed in Infants and Children?

Infants and children get assessed by a medical professional who takes a family history and conducts tests to determine if they may have lactose intolerance. 

A premature birth may have a higher risk of secondary lactose intolerance due to the digestive system not being developed enough to break down lactose. Congenital lactose intolerance may also cause infants and children to struggle with feeding. Doctors may prescribe lactase drops to increase lactase levels and avoid issues with breast milk, breastfeeding, or formula.

A stool acidity test, blood draw, and breath test will determine if an infant or child has a food allergy, intolerance, or other condition. Children with low lactase production may experience lactose intolerance, which can impact their nutrition and development.

A healthcare provider will check the amount of lactase the child produces and offer medical advice on how best to manage their condition.

How Do Doctors Rule Out Milk Allergy or Other Digestive Issues?

A doctor may use a skin prick test or a blood test to determine if you have a milk allergy. 

Food allergies and lactose intolerance have very different causes and solutions, although some overlap exists with the symptoms and side effects. Drinking milk if you have an intolerance may cause discomfort; however, drinking milk if you have an allergy can trigger life-threatening anaphylaxis.

A doctor rules out an allergy or food intolerance by conducting a wide range of tests, including blood tests, breath tests, skin prick tests, and sometimes even a biopsy of the small or large intestine. Your doctor may refer you to a gastroenterology specialist for an accurate diagnosis and treatment.

Managing and Treating Lactose Intolerance

How Can You Reduce or Eliminate Lactose From Your Diet?

Reduce or eliminate lactose in your diet by working with a registered dietitian (RD) or other medical professional to replace foods from your diet containing lactose. 

LifeSpring Home Nutrition can help you reduce lactose in your diet by providing you with weekly non-dairy, enriched foods that provide essential nutrients. You can use the flash-frozen meals to enhance your diet and improve your digestive health.

What Foods and Ingredients Should You Check on Labels?

Always check food labels for ingredients containing lactose or potential cross-contamination of lactose foods, including whey, curds, milk, casein, and dry milk solids. 

Food labels will warn you if facilities that made or packaged the food also prepare foods with lactose. A warning on the label will indicate whether milk, whey, or other high-lactose ingredients may have come into contact with that food. Additionally, food labels provide a comprehensive list of ingredients, enabling you to research how they may affect your diet.

Do Lactase Enzyme Supplements Really Help?

Yes, lactase enzyme supplements can significantly reduce symptoms related to lactose intolerance. 

Lactase supplements boost your body’s ability to digest lactose. You can safely eat more lactose in your diet if you use supplements and eat foods high in lactose to make up for your body’s natural lack of lactase.

LifeSpring Home Nutrition offers a variety of meals that include lactose-containing foods, which can help enhance your diet and overall health.

Can Probiotics Improve Lactose Digestion?

Yes, some probiotics may help minimize symptoms related to food intolerances and improve lactose digestion for some people. 

Probiotics are microorganisms that provide health benefits. Non-dairy yogurts, kimchi, sauerkraut, and other lactose-free fermented foods can improve your gut health and digestion by introducing probiotics into your gut. Some probiotic strains produce lactase that helps your body digest lactose.

How Much Lactose Can Most People Tolerate?

Most people with lactose intolerance can tolerate a cup of milk in one sitting or two cups in a 24-hour period. 

The majority of people with lactose intolerance can tolerate small amounts of lactose when consumed with meals. However, you should consult with a dietitian or other healthcare professional to determine how much lactose you can tolerate based on the underlying causes of your condition and the severity of your symptoms.

How Can You Get Enough Calcium and Vitamin D Without Dairy?

Many drinks, foods, and supplements contain vitamin D, allowing you to get the recommended amount of vitamin D without consuming dairy products.

You can get enough calcium and vitamin D in your diet by introducing the following foods: 

• Leafy greens, including kale and broccoli 
• Plant-based milk
• Fish
• Almonds
• Tofu 
• 100% fruit or vegetable juice

You may also benefit from supplements if you have a specialized diet that does not allow you to introduce lactose-free alternatives into your weekly meals.

Living Well With Lactose Intolerance

What Are Some Easy Lactose-Free Meal and Snack Ideas?

Hummus, chickpeas, vegetables, fresh fruit, and other lactose-free foods make excellent snacks and meals. 

You can avoid dairy foods and snacks like ice cream, veggies and salad dressings, cow’s milk, and hard cheeses by replacing them with alternatives that use almond or soy milk.

Taking over-the-counter lactase supplements may also allow you to eat a small amount of lactose in your meals and snacks. An expert or other healthcare professional can provide you with information about how best to adjust your diet to manage lactose intolerance.

Replacing foods involves finding ways to replace the nutrients you remove from your diet by switching to foods with lower lactose content.

Creating a balanced meal plan can help you prevent nutrient deficiencies. Your primary care doctor can help you determine if you may benefit from nutritional supplements or specific foods to ensure you avoid vitamin or mineral deficiencies.

What Should You Do If Symptoms Don’t Improve?

If symptoms persist or worsen, consult a healthcare professional to determine if you may require additional testing or treatment to manage your condition effectively. 

Ideally, you will have a primary doctor or other medical provider assisting you in monitoring and managing your lactose intolerance. If your symptoms fail to improve or worsen, you should seek medical support to ensure there is not another medical issue complicating your condition.

Frequently Asked Questions About Lactose Intolerance

Does lactose intolerance go away?

Some instances of lactose intolerance may be temporary due to the root cause being an injury, illness, or other temporary health issue; however, lactose intolerance generally does not resolve on its own. 

Primary lactose intolerance never goes away and may worsen over time as you age due to natural changes in the body. Secondary lactose intolerance, which often has a sudden onset due to temporary health issues or medication, typically resolves once the underlying problem is addressed.

LifeSpring Home Nutrition offers medically tailored and recovery-boosting meals to help people recover from conditions that may have triggered temporary lactose intolerance.

Can you be lactose intolerant and still eat some dairy?

Yes. Most people with managed lactose intolerance can consume a small amount of dairy products, typically up to two cups or 24 grams per day. 

Eating or drinking a small amount of dairy and monitoring your response to various foods to determine which ones cause fewer symptoms allows you to still eat some dairy in your meals. Monitor how your body reacts to dairy products and consult a medical professional if you are uncertain about introducing or maintaining certain foods in your diet.

Each person has different responses to foods with lactose, and you may be able to handle more of one type of food than someone else.

What happens if you keep eating dairy with lactose intolerance?

Continuing to consume dairy without managing lactose intolerance can cause health problems, including dehydration, nutrient deficiencies, and gastrointestinal issues. 

Most people with lactose intolerance do not adopt an entirely lactose-free diet. Instead, they severely limit the amount of lactose they consume to reduce and manage symptoms.

LifeSpring Home Nutrition offers dairy-free meal options to help you limit the amount of lactose in your weekly diet.

Why am I suddenly lactose intolerant?

Secondary lactose intolerance may develop abruptly, including infections, diseases, injuries, and some types of cancer treatment. 

The causes of lactose intolerance can be linked to medications or temporary conditions that trigger a sudden onset of secondary lactose intolerance.