No it will not re-crystalize once in the body, and it is safe to inhale also, refer to the safety product sheets for example on vicks vaporub or other topical or inhalation menthol based products, even muscle pain topical ointments/gels/cremes have menthol that get absorbed topically and by inhalation on use, and the menthol flavorings are also safe based on using the same chemicals in juices that are used for the before mentioned products and applications. Sleep (and breath) easy lol