If you do not feel a positive impact on your osteoarthritis within the use of the first 8 oz. bottle, just send the remaining portion (even the empty bottle) back to us within 60 days of purchase for a full and prompt refund. If using Synflex with you pet, you should see a positive impact in your pet after the first 8 oz. bottle. If not, send it back to us within 60 days of purchase and we will issue a full and prompt refund.