Short answer: Neither clearly. In the GAIT trial of 1,583 people with knee osteoarthritis, glucosamine, chondroitin and the two together were not significantly better than placebo for pain over 24 weeks; celecoxib was.1 NIH says it is still uncertain whether either helps knee symptoms, and guidelines disagree.2
| Glucosamine | Chondroitin | |
|---|---|---|
| What it is | A building block of cartilage molecules2 | A part of cartilage that helps it resist compression2 |
| GAIT amount (study protocol) | 1,500 mg a day1 | 1,200 mg a day1 |
| GAIT response vs placebo (60.1%) | 3.9 points higher, not significant1 | 5.3 points higher, not significant1 |
| Hand osteoarthritis | Little evidence2 | One 6-month trial of 162 people found less pain; ACR conditionally recommends it2 |
| Hip osteoarthritis | 2-year trial of 222 people: no better than placebo2 | Little evidence2 |
| Safety notes | May raise blood sugar; bleeding risk with warfarin2 | Bleeding risk with warfarin2 |
GAIT randomly assigned 1,583 people with knee osteoarthritis to glucosamine, chondroitin, both, the prescription drug celecoxib, or placebo for 24 weeks. A 20% drop in pain happened in 60.1% on placebo. Glucosamine was 3.9 points higher, chondroitin 5.3 and the combination 6.5, none significant; celecoxib was 10.0 points higher and significant. In an exploratory look at people with moderate to severe pain, the combination did better than placebo (79.2% vs 54.3%). Side effects were mild and even across groups.1
A 2018 analysis of 29 studies cited by NIH found each taken alone reduced pain but the combination did not.2 These are study protocols, not personalized advice; confirm any dosing with your prescriber.
NIH summarizes the split: the American College of Rheumatology and Arthritis Foundation strongly recommend against both for knee osteoarthritis, the American Academy of Orthopaedic Surgeons lists both as possibly helpful, and a European group recommends only prescription-grade forms.2
No major safety problems turned up in large studies, but glucosamine may raise blood sugar, and both have been linked to more bleeding with warfarin.2 More detail: Curcumin vs ginger: how do the two roots compare?, and the Glucosamine and Chondroitin Sulfate guides.