GNC, a major health store chain, sells TriFlex with hyaluronic acid, claiming that supports healthy joint function and minimises joint pain. Along with HA, it contains glucosamine, chondroitin and methylsulfonylmethane. GNC's website notes "generally mild" side effects when users take the supplement properly.
Hyaluronic acid functions as an anti-inflammatory and lubricant in joints and eyes. Physician and medical writer Ray Sahelian names a skin rash as the only known side effect of taking HA as a supplement.
The University of Maryland Medical Center states that glucosamine poses only minor side effects, including heartburn, gas, bloating, indigestion, skin rash, nausea, stomach upset and diarrhoea. Some glucosamine supplements contain shellfish, so people with allergies should be cautious. It may also decrease the effect of insulin.
Some people may have mild upset stomach, diarrhoea, nausea, oedema, hair loss and constipation when taking chondroitin, according to New York's Hospital for Special Surgery, but it has no known drug interactions.
Methylsulfonylmethane ranks as one of the least toxic components in studies, reports the Iowa State University's Food and Nutrition Extension. However, the Hospital for Special Surgery found that it may cause headache, diarrhoea and nausea.