Glucosamine

No, it’s not possible to measure your body’s glucosamine levels. See your doctor if you have symptoms of osteoarthritis. Your doctor can diagnose if it is osteoarthritis or if it’s another condition such as rheumatoid arthritis.

• You can find glucosamine supplements in pharmacies, health shops and supermarkets.
• Supplements can be found as tablets, capsules and liquid formulations with or without the supplement chondroitin.
• They are available in two different salt forms – glucosamine sulphate and glucosamine hydrochloride.
• The glucosamine in manufactured supplements is usually made from shellfish such as crab, lobster or shrimp shells, but some supplements are made from a plant form of glucosamine.
• In Aotearoa New Zealand glucosamine is not registered as a medicine but is considered a health supplement.
• If you are considering taking supplements, get advice from your pharmacist or doctor first. Read the manufacturer's instructions for the dose you need to take and any special instructions.

It is not clear if glucosamine supplements are useful for symptoms or joint structure of osteoarthritis. Overall, there is little evidence of benefit. Glucosamine supplements are not specifically recommended for the treatment of osteoarthritis.

However, many patients use these supplements and report beneficial effects. Some find benefits after 3–6 months. Some trials show a small benefit after 2–3 years of use, other trials show no benefit.

The evidence shows that glucosamine sulphate is more effective than glucosamine hydrochloride. If glucosamide is taken, a dose of 1500 mg daily may be tried but should be stopped if there is no improvement after 3 months.

Glucosamine is not known to cause any major side effects. Common mild side effects include:

• nausea (feeling sick)
• indigestion, stomach upset
• stomach pain or cramps
• diarrhoea (runny poo)
• drowsiness
• headache
• tiredness.

Since glucosamine supplements can be made from shellfish, people with seafood allergies should avoid taking them. 

Glucosamine can affect the way your body handles sugar, especially if you have diabetes or other blood glucose problems, such as insulin resistance or impaired glucose tolerance. 

Read more about medicines and side effects and reporting a reaction you think might be a side effect.

Glucosamine supplements interact with the anticoagulant medicine warfarin. Ask your doctor or pharmacist to check for any medication interactions before you consider taking glucosamine supplements.