Overview

D-mannose is a simple sugar that is available over-the-counter as a dietary supplement. It is commonly used to treat or prevent kidney or bladder infections. However, it may not be helpful for preventing these infections, and its benefits for treating these infections are not well defined. Common side effects include diarrhea and burning in the vagina. Before taking D-mannose, tell your health care provider about all of your health conditions and any medicines or supplements you may be using.

Uses

What is D-mannose used for?

D-mannose is commonly used for kidney and bladder infections (urinary tract infections or UTIs), although its benefits are not well defined.

D-mannose is also used to treat a very rare, genetic condition called carbohydrate-deficient glycoprotein syndrome type 1b (MPI-CDG).

Note: The FDA has not reviewed D-mannose for safety and effectiveness. Learn more about dietary supplements here.

How does D-mannose work (mechanism of action)?

D-mannose is a simple sugar that is naturally found in some fruits and vegetables. In animals, D-mannose can block bacteria from binding to the wall of the bladder, reducing the risk of urinary tract infections (UTIs). But it may not work the same way in humans. Research in women who get multiple UTIs each year shows that taking D-mannose does not prevent UTIs. The benefits of D-mannose for treating an existing UTI are not well defined.

Your body needs small amounts of D-mannose to function properly. To do this, it usually turns other simple sugars, such as fructose, into D-mannose. But people with a very rare, genetic condition called carbohydrate-deficient glycoprotein syndrome type 1b (MPI-CDG) are not able to do this. Taking D-mannose may help reduce certain symptoms in some people with this condition.

How should I store D-mannose?

You should store D-mannose according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of D-mannose?

The most common side effects of D-mannose are listed below. These side effects may vary depending on the dose you are taking or the specific product you are using. Tell your health care provider if you have any of these side effects that bother you.

• Diarrhea
• Burning in the vagina

There may be other side effects of D-mannose that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of D-mannose?

While less common, the most serious side effects of D-mannose are described below, along with what to do if they happen.

Severe Allergic Reactions. D-mannose may cause allergic reactions, which can be serious. Stop taking D-mannose and get help right away if you have any of the following symptoms of a serious allergic reaction.

• Breathing problems or wheezing
• Racing heart
• Fever or general ill feeling
• Swollen lymph nodes
• Swelling of the face, lips, mouth, tongue, or throat
• Trouble swallowing or throat tightness
• Itching or skin rash
• Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
• Nausea or vomiting
• Dizziness, feeling lightheaded, or fainting
• Stomach cramps
• Joint pain

Precautions

Who should not use D-mannose?

Allergies to Ingredients. People who are allergic to any of the following should not take D-mannose.

• Carubinose
• D-mannose
• Mannose
• Seminose
• Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific D-mannose products they stock.

What should I know about D-mannose before using it?

D-mannose is a dietary supplement. It cannot be marketed to treat or cure a disease.

Read and follow the directions on the specific product you are taking, or take it as recommended by your health care provider.

Keep D-mannose out of the reach of children.

If you have symptoms of an infection in the kidney or bladder (also known as a urinary tract infection, or UTI), call your health care provider. Symptoms may include burning when you pee, feeling an urgent or frequent need to pee, or cloudy, bloody, or strange-smelling pee. It is important to seek effective treatment for a UTI as soon as you have symptoms. It is not clear if D-mannose can help treat a UTI.

If you get UTIs regularly or more than once each year, speak to your health care provider about the best ways to prevent a UTI. D-mannose does not seem to be helpful for preventing UTIs.

D-mannose is a simple sugar. Your body uses other simple sugars, such as fructose and glucose, for energy. But it does not use D-mannose for energy, and D-mannose does not seem to increase blood sugar levels by a meaningful amount. Despite this, most dietary supplements that contain D-mannose list it as an “added sugar” on their product labels. If you are taking D-mannose powder or a drink that contains D-mannose, read the product label carefully. Some products may also contain other sugars that can increase your blood sugar levels.

The FDA has not tested D-mannose products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.

What should I tell my health care provider before using D-mannose?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if D-mannose is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions.Tell your health care provider if you have or have had any of the following.

• Diabetes
• Kidney problems
• Multiple kidney or bladder infections

Pregnancy. It is not known if or how D-mannose could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. It is not known if D-mannose passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does D-mannose interact with foods or drinks?

There are no known interactions between D-mannose and foods or drinks.

It is unknown if drinking alcohol will affect D-mannose.

Does D-mannose interact with medicines (drug interactions)?

There are no known interactions between D-mannose and medicines. Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

The interactions between D-mannose and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with D-mannose is incomplete. Always check with your health care provider before taking D-mannose with any medicines.

Dosing

What should I do if I accidentally use too much D-mannose?

If you or someone else has used too much D-mannose, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

Read the product label closely and speak to a health care provider about how to take D-mannose safely. Do not take double or extra doses, even if you miss a dose.