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Overview: Glucosamine is a dietary supplement that is available over the counter. People often take glucosamine for certain types of arthritis, but its benefits are not well defined. Common side effects may include upset stomach or increased blood sugar levels. Glucosamine comes in different forms, such as glucosamine sulfate and glucosamine hydrochloride. Before taking glucosamine, make sure to tell your health care provider about any health conditions you have or medicines you are taking.

Uses

What is glucosamine used for?

Glucosamine is commonly used for osteoarthritis, although its benefits are not well defined.

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

How does glucosamine work (mechanism of action)?

Glucosamine is naturally present in the cartilage (which acts like a cushion) in your joints. It is part of a substance called glycosaminoglycan, which acts as a building block for your cartilage.

Glucosamine supplements can raise the levels of glucosamine in your body. This could help support the cartilage in your joints that are affected by osteoarthritis. But the benefits of glucosamine for osteoarthritis are not clear. Many different studies have been done to see if glucosamine can help with osteoarthritis; some studies have shown benefit, while others have not.

Studies on glucosamine may have shown different results because they used different glucosamine products. Glucosamine comes in two main forms: glucosamine sulfate and glucosamine hydrochloride. Also, the quality of the glucosamine products used in these studies was not always the same. Both the form and quality of a glucosamine product can affect how it works in the body. If you are taking glucosamine and you switch to a different brand, you may not have the same effects. 

How is glucosamine supplied (dosage forms)?

Brands and other names

  • Move Free Joint Health
  • OptiFlex
  • Osteo Bi-Flex

Dosage forms and strengths

Glucosamine is a dietary supplement that comes in various forms, such as a capsule, liquid, or tablet that is swallowed. Glucosamine is commonly found in products that also contain other ingredients, such as chondroitin.

How should I store glucosamine?

You should store glucosamine 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 glucosamine?

The most common side effects of glucosamine 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.

There may be other side effects of glucosamine 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 glucosamine?

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

Severe Allergic Reactions. Glucosamine may cause allergic reactions, which can be serious. Stop taking glucosamine 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, which can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use glucosamine?

Allergies to Ingredients. People who are allergic to any of the following should not take glucosamine.

  • Glucosamine
  • Move Free Joint Health
  • N-acetyl glucosamine
  • OptiFlex
  • Osteo Bi-Flex
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific glucosamine products they stock.

What should I know about glucosamine before using it?

Glucosamine 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 glucosamine out of the reach of children.

Glucosamine dietary supplements may contain different forms of glucosamine, including glucosamine hydrochloride and glucosamine sulfate. It is not clear if these two forms of glucosamine work differently in the body. Glucosamine dietary supplements may also contain another ingredient, called chondroitin. It is important to read the product label closely to check which ingredients it contains. 

The FDA has not tested glucosamine 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 glucosamine?

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 glucosamine is right for you.

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

Diabetes. Glucosamine can increase blood glucose levels in some people. If you have diabetes, talk to your health care provider before taking glucosamine.

Shellfish Allergy. Some glucosamine products are made from the shells of shellfish. If you are allergic to shellfish, talk to your health care provider before taking glucosamine.

Other Medicines and Supplements. Glucosamine may interact with other medicines and supplements. Before taking glucosamine, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

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

Breastfeeding. Glucosamine passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does glucosamine interact with foods or drinks?

There are no known interactions between glucosamine and foods or drinks.

It is unknown if drinking alcohol will affect glucosamine.

Does glucosamine interact with medicines (drug interactions)?

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.

In particular, make sure that you discuss if you are using warfarin, which is a blood thinner.

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

Overdose/Missed Dose

What should I do if I accidentally use too much glucosamine?

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

Glucosamine dietary supplements come in many forms and may also contain other ingredients. Read the product label closely and speak with a health care provider about how to take glucosamine safely. Do not take double or extra doses, even if you miss a dose.