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What Is Anhydrous Lactose?

author image Adam Cloe Ph.D./M.D.
Adam Cloe has been published in various scientific journals, including the "Journal of Biochemistry." He is currently a pathology resident at the University of Chicago. Cloe holds a Bachelor of Arts in biochemistry from Boston University, a M.D. from the University of Chicago and a Ph.D. in pathology from the University of Chicago.
What Is Anhydrous Lactose?
Five bottles of milk lined up on a white counter. Photo Credit: karandaev/iStock/Getty Images

Sometimes medications contain compounds that are provide no medicinal value. Anhydrous lactose is found in some tablets and other kinds of drugs and generally does not cause any health problems, but it can be problematic if you are lactose intolerant. Talk to your doctor if you are concerned about the effects of anhydrous lactose.

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Lactose is a kind of sugar found naturally in dairy products such as milk, cheese and cream. Lactose consists of two different sugars: glucose and galactose, which are chemically linked together. Anhydrous lactose is lactose that has no water in it. To make anhydrous lactose, lactose is dried at very high temperatures on a device known as a roller dryer. This helps remove all water molecules and crystals.


Anhydrous lactose is often found as an inactive ingredient in different medications. It can be used as a filler to help increase the size of a capsule or tablet; it can also be added to dry powder inhalers to help propel the medications. Anhydrous lactose is particularly useful because it contains no water, which means that it will not react with medications that are sensitive to moisture. Anhydrous lactose may also be used as a coating for pills because of its mildly sweet taste.

Lactose Intolerance

Although lactose is safe for most people to consume, you may need to avoid products with lactose if you are lactose intolerant. Lactose intolerance is caused by low levels of the enzyme lactase. Lactase is found in the intestines and is needed to break down lactose into glucose and galactose. Without lactase, your intestines cannot absorb lactose. If you are lactose intolerant and consume lactose, you may develop gas, diarrhea, bloating or abdominal pain.


Anhydrous lactose as an inactive ingredient may trigger digestive tract problems if you are lactose intolerant. However, the levels of lactose in most medications are relatively low, so the presence of anhydrous lactose should only cause problems if you are extremely sensitive to lactose. If you have concerns about your medication, talk to your doctor to see if there are lactose-free formulations available.

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