Recent media reports have raised concern over the use of glucosamine in the treatment of osteoarthritis after The Australian Rheumatology Association (ARA) released a statement advising people not to take the supplement due to possible allergic side-effects.
These reports appear to be based on two unrelated recent events:
(1). A change in recommendation by the American College of Rheumatology (ACR) 
In October 2019, the ACR updated their guidelines for the management of osteoarthritis from;
A longstanding conditional recommendation against the use of glucosamine for osteoarthritis on the basis that it probably does not help, to
A strong recommendation against the use of glucosamine for osteoarthritis on the basis that it convincingly does not help.
They did not cite new safety concerns.
(2). A recent paper highlighting the known risks associated with glucosamine, particularly in people with shellfish allergy 
This paper reviewed 366 glucosamine related adverse drug reactions reported to the Therapeutic Goods Administration between 2000-2011, including 43 classified as severe, possibly related to the known risks of glucosamine in those with shellfish allergy. This highlights a valid concern but the number of adverse events needs to be considered in the context of the many hundreds of thousands of people who took glucosamine during that period. This suggests that severe adverse reactions are very uncommon.
Many other osteoarthritis treatment guidelines make conditional recommendations against the use of glucosamine on the basis that it probably does not help, including The Royal Australian College of General Practitioners guideline for the management knee and hip OA .
What is glucosamine?
Glucosamine is a naturally occurring substance the body uses to help build joint tissue, such as cartilage and tendons. In a supplement, the glucosamine can be made from the shells of prawns and other crustaceans, or it can be made synthetically in a factory.
Is glucosamine dangerous?
Beyond allergic reactions, there are other safety concerns about glucosamine.
For instance, if you are taking glucosamine and a medicine that thins your blood (such as warfarin after a stroke), this can increase your risk of bleeding.
Glucosamine supplements have also been implicated in chronic liver disease and in worsening underlying asthma. Some patients may also experience digestive symptoms such as heartburn.
The risks of other side-effects seem unclear, including whether it raises blood glucose levels in people with or without diabetes.
Arthritis Australia and Australian Rheumatology Association comment:
This information highlights growing evidence that glucosamine does not help people with osteoarthritis and is a reminder that people with shellfish allergy should not take glucosamine (which is commonly derived from shellfish). It does not identify any new safety concerns and should not cause undue alarm in people already taking glucosamine.
Comment from the Royal Australian College of General Practitioners (RACGP):
Dr Harry Nespolon, President of the RACGP stated “The RACGP does not recommend the use of glucosamine as a way of preventing osteoarthritis. If you have concerns about using glucosamine or treatment for osteoarthritis I recommend you have a chat with your local GP about the options available to you.”
References: https://www.rheumatology.org/Portals/0/Files/Osteoarthritis-Guideline-Early-View-2019.pdf  https://www.ncbi.nlm.nih.gov/pubmed/31597786  https://rheumatology.org.au/gps/clinical-guidelines.asp
I’m taking glucosamine for my arthritis. So what’s behind the new advice to stop?. [online] Health Times. Available at: https://healthtimes.com.au/hub/pain-management/44/news/ht1/im-taking-glucosamine-for-my-arthritis-so-whats-behind-the-new-advice-to-stop/4749/