One FELIWAY diffuser refill will last up to 30 days. We recommend replacing the refill every four weeks, even if there is still a small amount of liquid left inside the vial. The vial can never be completely empty as the last drops of liquid are not sufficient for the diffusion process to occur.
With continuous use, a FELIWAY diffuser lasts six months. After six months have
passed, it’s best to replace the diffuser to ensure optimum effectiveness.