Can you take glucosamine while breastfeeding?

What LactMed says

The National Library of Medicine’s own summary, quoted in full. We do not write a verdict of our own on this question, and we do not compress theirs into a label.

Glucosamine is an amino-monosaccharide that is either derived from shellfish or synthetically produced. Glucosamine sulfate has no specific lactation-related uses. It is most commonly used to treat osteoarthritis. A glucosamine derivative, N-acetylglucosamine, is a normal component of human breastmilk. Glucosamine sulfate is well tolerated with occasional gastrointestinal discomfort (e.g., diarrhea, heartburn, nausea, vomiting) reported. Although no studies exist on the use of glucosamine sulfate during breastfeeding, its use by a nursing mother is unlikely to adversely affect the breastfed infant.

Dietary supplements do not require extensive pre-marketing approval from the U.S. Food and Drug Administration. Manufacturers are responsible to ensure the safety, but do not need to prove the safety and effectiveness of dietary supplements before they are marketed. Dietary supplements may contain multiple ingredients, and differences are often found between labeled and actual ingredients or their amounts. A manufacturer may contract with an independent organization to verify the quality of a product or its ingredients, but that does not certify the safety or effectiveness of a product. Because of the above issues, clinical testing results on one product may not be applicable to other products. More detailed information about dietary supplements is available elsewhere on the LactMed Web site.

Quoted from Glucosamine — Drugs and Lactation Database (LactMed®), National Institute of Child Health and Human Development, revised May 17, 2021.