The most common side effects of glucosamine are nausea, heartburn, diarrhea and constipation, states WebMD. A few users experience drowsiness, skin reactions or headaches. It is also possible for the supplement to affect blood sugar levels during and after surgery, so it should be avoided two weeks before an operation.
Sometimes side effects appear when glucosamine is paired with certain medications, warns MedlinePlus. It seems to enhance the effects of warfarin, causing blood clotting to slow too much. The supplement possibly interferes with some chemotherapy drugs. While these anti-cancer medicines slow the rate of tumor cell reproduction, it is possible that glucosamine speeds up the copying process.
Glucosamine is a naturally occurring substance, and it is a component of the fluid surrounding human joints and is also found in found in crustacean shells, MedlinePlus states. However, some glucosamine supplements are completely manufactured in laboratories.
On occasion, people who have osteoarthritis use glucosamine supplements, says MedlinePlus. For many people, glucosamine appears to be about as effective but not as fast-acting as over-the-counter pain relievers. Long-term osteoarthritis sufferers, senior citizens and overweight individuals do not seem to receive pain relief benefits. Some evidence indicates that glucosamine slows the deterioration of joints. Research has primarily focused on arthritis in knees.