A 60-day guarantee is advertised. A third-party source says empty bottles can be returned for a refund minus the initial shipping cost, while other sections mention a 14 to 60-day period and return postage rules. It also advises choosing a one-time purchase to avoid subscriptions and buying only from the official site, because third-party purchases may void the guarantee.
Read the refund terms on the official checkout page before ordering, request refunds from the official seller, not this website, and keep your order confirmation and bottles.