Although both are very popular non-surgical treatments, they work in completely different ways. Hyaluronic acid is a dermal filler that is injected to restore volume, fill static wrinkles and shape facial features, and its effect is immediate and physically visible. Botulinum toxin, on the other hand, acts on the muscles that generate expression wrinkles such as those on the forehead or between the eyebrows, relaxing them to soften the lines. In many cases both treatments complement each other perfectly: botulinum toxin softens wrinkles and hyaluronic acid fills and restores lost volume.