The best discount code for oxygenadvantage.com is 'thrivetools', which provides a 10% discount. Additionally, there are two more discount codes available. The code 'breathebetter5' offers a 5% discount on all products from the store. The code 'oaonlinecourse10' provides a 10% discount on certain online courses. Please note that these codes are subject to change and it's always a good idea to check the website for the most current promotions. Enjoy your shopping!