Lactose intolerance is caused in part by a shortage of lactase, an enzyme produced by the cells that line the small intestine. Lactase breaks lactose down into simpler forms of sugar, like glucose, so they can be absorbed and used by the body.

Infants have the highest levels of lactase, which helps them digest their mother’s milk. In about 70% of the world’s population, a genetic trait causes lactase levels to start going down after babies are weaned. This drop is irreversible and most lactase activity is lost by adulthood.

Even though most people experience this drop, they won’t all have symptoms after eating or drinking normal amounts of lactose. Whether you do or not seems to be linked to the ability of a certain type of “good” bacteria, called lactic acid bacteria, to break down lactose.

But among those who do have symptoms, the uncomfortable result is usually gas, bloating, and diarrhea.

This article talks about the symptoms of lactose intolerance and ways you can both prevent and treat it at home. It also will help you to know when it’s time to see a healthcare provider for treatment.

Lactose Intolerance Symptoms

Symptoms of lactose intolerance include:

GasCrampingAbdominal painNauseaBloatingDiarrhea

Undigested lactose causes diarrhea by drawing large amounts of your body’s water into the intestines. Bacteria in the gut also feed on the lactose and produce hydrogen, which in turn causes gas and bloating.

Symptoms of lactose intolerance typically begin between 30 minutes and two hours after you eat or drink products with lactose in them. They continue until it’s out of your system—which can be as long as 48 hours later.

How to End Lactose Intolerance Pain

The best way to manage lactose intolerance symptoms is to prevent them. You do that simply by avoiding foods that cause them. But if you do eat or drink something that has lactose in it, you can take steps to reduce the symptoms it causes.

Black peopleNative AmericansAsian AmericansLatinx

People of European descent are least likely to be lactose intolerant.

You may find help with over-the-counter treatments for your specific symptoms. For example:

If you have gas and bloating, try a product like Gas-X (simethicone). If you have diarrhea, take a medication like Imodium AD (loperamide). If you have diarrhea along with gas and bloating, you can try Imodium capsules (which contain both loperamide and simethicone) or Pepto Bismol (bismuth subsalicylate).

Prevention

Many people try using dietary supplements to prevent the discomfort of lactose intolerance. So far, there’s a lack of scientific support for claims that these treatments work, but a few are in common use.

Acidophilus and Other Probiotics

Lactic acid bacteria in the intestines break lactose down into simpler sugars that can be absorbed by the colon.

Supplements may help with this process. They are available in capsule, tablet, or powder form. You can find them in health food stores, grocery stores, drugstores, and online.

There are quite a few types of lactic acid bacteria. The ones used most often for lactose intolerance include:

Lactobacillus acidophilus Lactobacillus bulgaricus Streptococcus salivarius Lactobacillus reuteri Lactobacillus plantarum Streptococcus thermophilus

A study published in 2021 compared the results of 55 people with lactose intolerance, divided into two groups. For a week, half were given yogurt containing acidophilus and Bifidobacterium sp., another type of probiotic bacteria. The other half were given yogurt without it.

The results suggested that the probiotics did help reduce symptoms. The findings were similar to those drawn from 15 other studies that researchers reviewed to see how different probiotics might help with lactose intolerance. They found positive effects for some of them, including acidophilus and Bifidobacterium sp.

Other research, however, has shown mixed results on probiotic use for lactose intolerance. An older systematic review, completed in 2005 and published in the Journal of Family Practice, found variations across seven studies that were included.

One showed a significant reduction in symptoms, another had mixed results, and five studies showed no benefit. The authors noted that each study used a different type of lactic acid bacteria.

Yogurt

In alternative medicine, yogurt containing live active bacteria is believed to help people to digest lactose. When yogurt is consumed, bile acids disrupt the cell walls of the bacteria in yogurt. This releases a key enzyme into the intestines that can boost lactose digestion.

Acidophilus Milk

Acidophilus milks are made by adding Lactobacillus acidophilus to cold milk. Many studies that have looked at its effects on lactose digestion have found no improvement. Researchers think it may be because the products used in the studies did not contain enough live acidophilus.

Lactase Supplements

Tablets containing lactase can be taken before eating foods with lactose. For many people, lactase supplements are only needed when they eat or drink large amounts of lactose.

Diet

It’s quite common for people to avoid lactose-containing foods completely. This usually isn’t necessary and may even cause your calcium levels to become too low.

if you have lactose intolerance, you can try making changes to your diet. You can:

Drink less than one cup of milk at a time. Eat milk and milk products with meals rather than alone. Try reduced-lactose milk. Try yogurt instead of milk.

Safety and Precautions

Most supplements haven’t been tested for safety. This is due to the fact that dietary supplements are largely unregulated.

The contents also may not always match the list or amount on the product label. It’s a good idea to check for certification from an independent lab, such as the U.S. Pharmacopeia (USP), in order to know for sure what you are getting.

Also keep in mind that the safety of lactase supplements has not been established in people who are pregnant or nursing, children, and those with medical conditions or who take medications.

When to See Your Healthcare Provider

If you have new symptoms that could point to lactose intolerance, it’s important to talk with your healthcare provider. You should make an appointment if you have:

A change in your bowel habitsConstipation, diarrhea, or gas that gets worseHeartburn that keeps you from sleepingOther symptoms that are causing concern

Lactose intolerance can also be caused by medications, or by another health condition that damages cells that line the intestines. These conditions may include:

Crohn’s disease Celiac disease Giardiasis HIV enteropathy Carcinoid syndrome Diabetic gastropathy Zollinger-Ellison syndrome Alcoholism Iron deficiency

Summary

Lactose intolerance is caused by naturally low levels of lactase in the body, but people who have it also may lack the “good” bacteria that help with digestion. This often causes digestion-related symptoms such as gas, cramping, and diarrhea.

Sudden or severe stomach painVomiting up blood or dark flecksBlack or bloody stoolsSevere or persistent constipationInability to keep anything down

Over-the-counter medicines and probiotic supplements are options to help relieve symptoms. There is some evidence to suggest the supplements can help. If you decide to use them, it’s important to learn about these products, select reputable brands, and discuss it with a healthcare provider first.

But if you have serious symptoms, like severe stomach pain or blood in your stools, be sure to seek help immediately. They suggest that there’s a problem you cannot treat by yourself.

A Word From Verywell

It’s too soon to recommend supplement treatments for lactose intolerance, but eating more probiotic-rich foods may help to improve your overall health. Talk to your healthcare provider about symptoms and possible treatments before starting anything new.